Assignment - Java String Operation about java HOT 26 CLOSED

package day8task01;

import javax.swing.JOptionPane;

/**
*

• @author DELL
  */
  public class Day8task01 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    String s1;
    String s2;
    int choice;
    choice = Integer.parseInt(JOptionPane.showInputDialog("1:concatination\n2:comparison\n3:upper/lowercase\n4:charAt(index)\n5:substring\n6:replace\n7:indexcheck\n8:trim\n\nYour choice????"));
    switch (choice) {
    case 1:
    s1 = JOptionPane.showInputDialog("enter first string");
    s2 = JOptionPane.showInputDialog("enter second string");
    JOptionPane.showMessageDialog(null, s1.concat(s2), "concatinated string", 1);
    break;

     case 2:
         s1 = JOptionPane.showInputDialog("enter first string");
         s2 = JOptionPane.showInputDialog("enter second string");
         if (s1.equals(s2)) {
             JOptionPane.showMessageDialog(null, "equal", "comparison", 1);
         }
         if (s1.equalsIgnoreCase(s2)) {
             JOptionPane.showMessageDialog(null, "not equal", "comparison", 1);
         }
         break;
    
     case 3:
         s1 = JOptionPane.showInputDialog("enter the string");
         JOptionPane.showMessageDialog(null, s1.toUpperCase(), " ", 1);
         JOptionPane.showMessageDialog(null, s1.toLowerCase(), " ", 1);
         break;
    
     case 4:
         s1 = JOptionPane.showInputDialog("enter the string");
         for (int i = 0; i < s1.length(); i++) {
             JOptionPane.showMessageDialog(null, s1.charAt(i), " ", 1);
         }
         break;
    
     case 5:
         s1 = JOptionPane.showInputDialog("enter the string");
         JOptionPane.showMessageDialog(null, s1.substring(0, 2), " ", 1);
         JOptionPane.showMessageDialog(null, s1.substring(3, 4), " ", 1);
         JOptionPane.showMessageDialog(null, s1.substring(4, 6), " ", 1);
         break;
    
     case 6:
         s1 = JOptionPane.showInputDialog("enter the string");
         JOptionPane.showMessageDialog(null, s1.replace("a", "A"), "", 1);
         break;
    
     case 7:
         s1 = JOptionPane.showInputDialog("enter the string");
         JOptionPane.showMessageDialog(null, s1.indexOf('a'), "Index of a", 1);
         break;
    
     case 8:
         s1 = JOptionPane.showInputDialog("enter the string");
         JOptionPane.showMessageDialog(null, s1.trim(), "Trimmed", 1);
         break;
    
     default:
         JOptionPane.showMessageDialog(null, "You should enter valid choice", "Error", 2);
    

    }

  }

}

from java.

package day8a1;

import static java.lang.Integer.parseInt;
import javax.swing.JOptionPane;

/**
*

• @author User
  */
  public class Day8A1 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {

    int ch;
    String s1, s2;
    JOptionPane.showMessageDialog(null,"1.Concatination\n2.Comparison\n3.toUpperCase/toLowerCase\n4.chatAt(index)\n5.Substring\n6.Replace\n7.indexOf(char)\n8.trim()", "Enter your choice", 3);
    ch = parseInt(JOptionPane.showInputDialog("Enter your choice"));
    switch (ch) {
    case 1:
    s1 = JOptionPane.showInputDialog("Enter first string!");
    s2 = JOptionPane.showInputDialog("Enter second string!");
    JOptionPane.showMessageDialog(null, s1.concat(s2), "After Concatination", 1);
    break;
    case 2:
    s1 = JOptionPane.showInputDialog("Enter first string!");
    s2 = JOptionPane.showInputDialog("Enter second string!");
    if (s1.equals(s2)) {
    JOptionPane.showMessageDialog(null, "Both String are same", "After Comparing", 1);
    } else {
    JOptionPane.showMessageDialog(null, "Both String are not same", "After Comparing", 1);
    }
    break;
    case 3:
    s1 = JOptionPane.showInputDialog("Enter a string!");
    JOptionPane.showMessageDialog(null, s1.toUpperCase(), "Uppercase of" + s1, 1);
    JOptionPane.showMessageDialog(null, s1.toLowerCase(), "Lowercase of" + s1, 1);
    break;
    case 4:
    s1 = JOptionPane.showInputDialog("Enter a string!");
    for (int i = 0; i < s1.length(); i++) {
    JOptionPane.showMessageDialog(null, s1.charAt(i), "Displaying" + s1, 1);
    }
    break;
    case 5:
    s1 = JOptionPane.showInputDialog("Enter a string");
    int l = s1.length();
    JOptionPane.showMessageDialog(null, s1.substring(0, 1), "Displaying first element ", 1);
    JOptionPane.showMessageDialog(null, s1.substring(l - 1, l), "Displaying last element ", 1);
    break;
    case 6:
    s1 = JOptionPane.showInputDialog("Enter your CRN");
    int len = s1.length();
    if (len < 6 || len > 6) {
    s1 = JOptionPane.showInputDialog("Enter a valid CRN");
    }
    String a = s1.replace(s1.substring(0, 2), "Batch" + 20 + s1.substring(0, 2) + "");
    JOptionPane.showMessageDialog(null, a);
    String b = s1.replace(s1.substring(3, 4), "Department" + s1.substring(3, 4) + "");
    JOptionPane.showMessageDialog(null, b);
    String c = s1.replace(s1.substring(4, 6), "Roll No" + s1.substring(4, 6) + "_");
    JOptionPane.showMessageDialog(null, c);
    break;
    case 7:
    s1 = JOptionPane.showInputDialog("Enter a string!");
    s2 = JOptionPane.showInputDialog("Enter string to be indexed");
    JOptionPane.showMessageDialog(null, s1.indexOf(s2));
    break;
    case 8:
    s1 = JOptionPane.showInputDialog("Enter a string!");
    JOptionPane.showMessageDialog(null, s1.trim());
    break;
    default:
    JOptionPane.showMessageDialog(null, "Invalid Choice");
    break;
    }
    }

}
O/P:
Enter your choice:

Choice 1:

Choice 2:

Choice 3:

Choice 4:

Choice 5:

Choice 6:

Choice 7:

Choice 8:

from java.

Program
package stringopercase;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;
import java.util.regex.Pattern;

/**
*

• @author m-lan
  */
  public class StringOperCase {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    int sn;
    String crn, s, s1, s2, n1, n2, dpt, dpt_name, np;
    Scanner input = new Scanner(System.in);
    System.out.println("Here are the Choices.Enter number to choose");
    System.out.println("1.Concatenation");
    System.out.println("2.Comparison");
    System.out.println("3.toUpperCase, toLowerCase");
    System.out.println("4.charAt(index)");
    System.out.println("5.Substring");
    System.out.println("6.Replace");
    System.out.println("7.indexOf(char)");
    System.out.println("8.trim()");

    System.out.printf("=>");
    sn = input.nextInt();
    switch (sn) {
    case 1:
    System.out.println("Enter first String:");
    s1 = input.next();
    System.out.println("Enter Second String:");
    s2 = input.next();
    System.out.println("String1=" + s1 + " " + "String2=" + s2);
    System.out.println("After Concatenating...");
    System.out.println(s1 + s2);
    System.out.println(s1.concat(s2));
    System.out.println(s1.concat(s2.concat(s1)));
    break;

     case 2:
         System.out.println("Enter first String:");
         n1 = input.next();
         System.out.println("Enter Second String:");
         n2 = input.next();
         System.out.println("String1=" + n1 + " " + "String2=" + n2);
         System.out.println("After Comparing...");
         if (n1.equals(n2)) {
             System.out.println("Given string Are same");
         }
         else{
             System.out.println("Given string Are Different");
         }
         if (n1.equalsIgnoreCase(n2)) {
             System.out.println("Given string Are same without considering Case");
         }
        else{
             System.out.println("Given string Are Different without considering Case");
         }
    
         break;
     case 3:
         System.out.println("Enter first String:");
         s1 = input.next();
         System.out.println("Enter Second String:");
         s2 = input.next();
         System.out.println("String1=" + s1 + " " + "String2=" + s2);
         System.out.println("After Changing to Upper and Lower Case and Capitalize...");
         System.out.println(s1.toUpperCase());
         System.out.println(s1.toLowerCase());
         System.out.println(StringUtils.capitalize(s1.toLowerCase()));
         break;
     case 4:
         System.out.println("Enter first String:");
         n1 = input.next();
         System.out.println("String=" + n1);
         System.out.println("Separating letter using charAt()...");
         for (int i = 0; i < n1.length(); i++) {
             System.out.println(n1.charAt(i));
         }
         break;
     case 5:
         System.out.println("Enter College Roll No.:");
         crn = input.next();
         if (Pattern.matches("[a-zA-Z]+", crn) == true || crn.length() > 6) {
             System.out.println("Invalid College Roll Number");
         } else {
             dpt = crn.substring(2, 4);
             if (dpt.equals("01")) {
                 dpt_name = "Civil Engineering";
             } else if (dpt.equals("02")) {
                 dpt_name = "Architecture";
             } else if (dpt.equals("03")) {
                 dpt_name = "Computer Engineering";
             } else if (dpt.equals("04")) {
                 dpt_name = "Electronics Engineering";
             } else {
                 dpt_name = "Unknown";
             }
             System.out.println("Batch:20" + crn.substring(0, 2));
             System.out.println("Department:" + dpt_name);
             System.out.println("Rollno.:" + crn.substring(4, 6));
         }
         break;
     case 6:
         System.out.println("Enter College Roll No.:");
         crn = input.next();
         if (Pattern.matches("[a-zA-Z]+", crn) == true || crn.length() > 6) {
             System.out.println("Invalid College Roll Number");
         } else {
             System.out.println("Rollno as a whole is " + crn);
             System.out.println("After Replacing...");
             String hh = crn.replace("71", "Batch 2071 ");
             System.out.println(hh.replace("03", "Computer "));
         }
         break;
     case 7:
         System.out.println("Enter String:");
         s = input.next();
         System.out.println("String is " + s);
         System.out.println("IndexOf");
         System.out.println("M=" + s.indexOf('M'));
         System.out.println("L=" + s.indexOf('L'));
         System.out.println("Last index of N=" + s.lastIndexOf('N'));
         break;
     case 8:
         System.out.println("Enter String with space like (   Nepal   ):");
         np = input.next();
         System.out.println("String with space is " + np);
         System.out.println("Without Trim = " + np);
         System.out.println("With Trim = " + np.trim());
         break;
     default:
         System.out.println("Invalid Choice");
    

    }
    }

}

Output

from java.

@milan604 Try to read required string from console too.

from java.

package stringoptions;

import java.util.Scanner;

/**
*

• @author Jagdish Duwal
  */
  public class StringOptions {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {

    String s,s1,s2 ;
    int i,j;
    String redo;
    Scanner input = new Scanner(System.in);

  do{

   System.out.println("Read the following menu");
   System.out.println("1. Concatenation \n2.comparison \n3. toUpperCase \n4.toLowerCase \n5.CharacterAt(index) \n6.Substring(index1, index2) \n7.Replace \n8.indexOf(char) \n9.lastIndexOf(char) \n10.trim  ");
   System.out.println("Enter your choice");
   int choice;
   choice = input.nextInt();
   
   switch(choice){
       case 1:
           System.out.println("Enter two strings to concatinate");
           System.out.println("1st string: ");
           s1 = input.next();
           System.out.println("2nd string: ");
           s2 = input.next();
           System.out.println("the concatinated string is "+ s1.concat(s2));
           break;
           
       case 2:
           System.out.println("Enter two strings to compare");
           System.out.println("1st string: ");
           s1 = input.next();
           System.out.println("2nd string: ");
           s2 = input.next();
           if(s1.equals(s2))
               System.out.println("the strings are same");
           else if(s1.equalsIgnoreCase(s2))
               System.out.println("the strings are same ignoring the case");
           else 
               System.out.println("the strings are not same");
           
           break;
  
       case 3:
           System.out.println("Enter a string to change into upper case");
           s1 = input.next();
           System.out.println("the string in upper case is : " + s1.toUpperCase());
           break;
           
       case 4:
           System.out.println("Enter a string to change into lower case");
           s1 = input.next();
           System.out.println("the string in lower case is : " + s1.toLowerCase());
           break;
           
       case 5:
           System.out.println("Enter a string");
           s1 = input.next();
           System.out.println("Enter a index to find the character at");
           i = input.nextInt();
           System.out.println("the char at the given index is: "+ s1.charAt(i));
           break;
           
       case 6:
            System.out.println("Enter a string");
           s1 = input.next();
           System.out.println("Enter a starting index");
           i = input.nextInt();
           System.out.println("Enter a ending ");
           j = input.nextInt();
           System.out.println("Using Substring operation "+ s1.substring(i, j));
           break;
           
       case 7:
           System.out.println("Enter a string");
           s = input.next();
           System.out.println("Enter the string you want to replace in string1");
           s1 = input.next();
           System.out.println("What do u want to replace it with? ");
           s2 = input.next();
           System.out.println("After replacing we get, "+ s.replace(s1,s2));
           break;
           
           
       case 8:
           System.out.println("Enter a string");
           s = input.next();
           System.out.println("Enter a character");
           s1 = input.next();
           System.out.println("the index of the character is: " + s.indexOf(s1.charAt(0)));
           break;
           
       case 9:
           
           System.out.println("Enter a string");
           s = input.next();
           System.out.println("Enter a character");
           s1 = input.next();
           System.out.println("the last index of the character is: " + s.lastIndexOf(s1.charAt(0)));
           break;
           
       case 10:
           System.out.println("Enter a string with spaces");
           s = input.next();
           System.out.println("String after trim: "+ s.trim());
           break;
           
           
       default:
           System.out.println("Invalid Entry. Please read the menu carefully");
  
   }
  System.out.println("Do you want to try again?(press y if yes)");
  redo = input.next();
  

  }while(redo.equalsIgnoreCase("y"));

  }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package day09task;

import java.util.Scanner;

/**
*

• @author Dragon15423
  */
  public class Day09Task {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    Scanner n = new Scanner(System.in);
    Scanner ne = new Scanner(System.in);
    System.out.println("String Operations:");

    System.out.print("Enter the 1st string: ");
    String s1 = ne.nextLine();
    System.out.print("Enter the 2nd string: ");
    String s2 = ne.nextLine();
    System.out.println("1)Concatenation\n2)Comparision\n3)toUpperCase or toLowerCase\n4)charAt(index)\n5)Substring\n6)Replace\n7)indexOf(char) and lastIndexOf(char)\n8)trim()");
    System.out.println("Enter your choice: ");
    int number = n.nextInt();
    switch (number) {

     case 1:
         System.out.println(s1 + s2);
         System.out.println(s1.concat(s2));
         System.out.println(s1.concat(s1.concat(s2)));
         break;
    
     case 2:
         if (s1.equals(s2)) {
             System.out.println("Strings are same");
         } else {
             System.out.println("They are different");
         }
         if (s1.equalsIgnoreCase(s2)) {
             System.out.println("Strings are same");
         } else {
             System.out.println("They are different");
         }
         break;
    
     case 3:
         System.out.println(s1.toUpperCase() + s2.toLowerCase());
         System.out.println(s1.toLowerCase() + s2.toUpperCase());
         break;
    
     case 4:
         for (int i = 0; i < s1.length(); i++) {
             char cha = s1.charAt(i);
             System.out.println(cha);
         }
         break;
    
     case 5:
         System.out.println(s1.substring(0, 2));
         System.out.println(s1.substring(3, 4));
         System.out.println(s2.substring(0, 5));
         break;
    
     case 6:
         System.out.println("Enter a roll no. = ");
         String roll = ne.nextLine();
         System.out.println("Your Roll no =" + roll);
         if (roll.length() == 6) {
             System.out.println("Batch 20" + roll.substring(0, 2));
             String com = roll.substring(2, 4);
             switch (com) {
                 case "01":
                     System.out.println("Civil Department");
                     break;
                 case "02":
                     System.out.println("Architecture Department");
                     break;
                 case "03":
                     System.out.println("Computer Department");
                     break;
                 case "04":
                     System.out.println("Electronics Department");
                     break;
                 default:
                     System.out.println("not valid");
                     break;
             }
         } else {
             System.out.println("not valid roll number");
         }
         break;
    
     case 7:
         System.out.println("Position of s =" + s1.indexOf('s'));
         System.out.println("Position of n =" + s1.lastIndexOf("n"));
         break;
    
     case 8:
         System.out.println("Enter a string with some spaces in the front:");
         String s3 = ne.nextLine();
         System.out.println("before trim = " + s3);
         System.out.println("after trim = " + s3.trim());
         break;
    
     default:
         System.out.println("not valid number");
    

    }
    }
    }
    
    
    
    
    
    
    
    
    

from java.

package day8a1;

import java.util.Scanner;

/**
*

• @author Albina Praz
  */
  public class Day8A1 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here

    Scanner input = new Scanner(System.in);
    Scanner a = new Scanner(System.in);
    Scanner b = new Scanner(System.in);
    String redo;
    System.out.println("String Operations:");
    System.out.print("Enter the 1st string: ");

    String s1 = a.nextLine();
    System.out.print("Enter 2nd string: ");
    String s2 = b.nextLine();
    System.out.print("Enter 3rd string");
    String s3 = a.nextLine();

    do {
    System.out.println("Enter the Choices");
    System.out.println("1.Concatenation");
    System.out.println("2.Comparison");
    System.out.println("3.toUpperCase, toLowerCase");
    System.out.println("4.charAt(index)");
    System.out.println("5.Substring");
    System.out.println("6.Replace");
    System.out.println("7.indexOf(char)");
    System.out.println("8.trim()");
    System.out.println("Enter your choice: ");
    int number = a.nextInt();
    switch (number) {
    case 1:
    System.out.println("String1=" + s1 + " " + "String2=" + s2);
    System.out.println("After Concatenating...");
    System.out.println(s1 + s2);
    System.out.println(s1.concat(s2));
    System.out.println(s1.concat(s2.concat(s3)));
    break;

         case 2:
             if (s1.equals(s2)) {
                 System.out.println("Strings are same");
             } else {
                 System.out.println("They are different");
             }
             if (s1.equalsIgnoreCase(s2)) {
                 System.out.println("Strings are same");
             } else {
                 System.out.println("They are different");
             }
             break;
    
         case 3:
             System.out.println(s1.toUpperCase() + s2.toLowerCase());
             System.out.println(s1.toLowerCase() + s2.toUpperCase());
             break;
    
         case 4:
             for (int i = 0; i < s1.length(); i++) {
                 char c = s1.charAt(i);
                 System.out.println(c);
             }
             break;
    
         case 5:
             System.out.println(s1.substring(0, 2));
             System.out.println(s1.substring(3, 4));
             System.out.println(s2.substring(4, 6));
             break;
    
         case 6:
             System.out.println("Enter a roll no. = ");
             String roll = b.nextLine();
             System.out.println("Your Roll no =" + roll);
             if (roll.length() == 6) {
                 System.out.println("Batch 20" + roll.substring(0, 2));
                 String com = roll.substring(2, 4);
                 switch (com) {
                     case "01":
                         System.out.println("Civil Department");
                         break;
                     case "02":
                         System.out.println("Architecture Department");
                         break;
                     case "03":
                         System.out.println("Computer Department");
                         break;
                     case "04":
                         System.out.println("Electronics Department");
                         break;
                     default:
                         System.out.println("not valid");
                         break;
                 }
             } else {
                 System.out.println("not valid roll number");
             }
             break;
    
         case 7:
             System.out.println("Position of s =" + s1.indexOf('s'));
             System.out.println("Position of n =" + s1.lastIndexOf("n"));
             break;
    
         case 8:
             System.out.println("Enter a string with some spaces in the front:");
             String s4 = b.nextLine();
             System.out.println("before trim = " + s4);
             System.out.println("after trim = " + s4.trim());
             break;
    
         default:
             System.out.println("not valid number");
     }
     System.out.println("Do you want to try again?(press y if yes)");
     redo = input.next();
    

    } while (redo.equalsIgnoreCase("y"));

  }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package stgoperate;

import java.util.Scanner;

/**
*

• @author LORDsajan
  */
  public class StgOperate {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    System.out.println("Strings operations");
    Scanner inp = new Scanner(System.in);
    String cont;
    System.out.println("enter what operation you want\n1>Concatenation\n2>Comparision\n3>toUppercase or toLowercase\n4>charAt(index)\n5>Substring\n6>Replace\n7>IndexOf(char)\n8>trim()");

    do {
    System.out.print("choice=");
    int choice = inp.nextInt();
    switch (choice) {
    case 1:
    System.out.println("enter two strings to concatinate");
    String s1 = inp.next();
    String s2 = inp.next();
    System.out.println("After concatination");
    System.out.println(s1.concat(s2));
    break;
    case 2:
    System.out.println("enter two strings to compare");
    String s3 = inp.next();
    String s4 = inp.next();
    if (s3.equalsIgnoreCase(s4)) {
    System.out.println("Its matches");
    } else {
    System.out.println("doesnt match1");
    }
    break;
    case 3:
    System.out.println("enter a string");
    String s5 = inp.next();
    System.out.println("after changing to upper case");
    System.out.println(s5.toUpperCase());
    System.out.println("after changing to lower case");
    System.out.println(s5.toLowerCase());
    break;
    case 4:
    System.out.println("enter a string");
    String s6 = inp.next();
    System.out.println("After seperating string into characters");
    for (int i = 0; i < s6.length(); i++) {
    System.out.println(s6.charAt(i));
    }
    break;

         case 5:
             String test1;
             do {
                 System.out.println("enter a string");
                 String s7 = inp.next();
                 System.out.println("enter the value for substring ");
                 int a = inp.nextInt();
                 int b = inp.nextInt();
                 if (a > s7.length() && b > s7.length()) {
                     System.out.println("invalid value");
                     test1 = "false";
    
                 } else {
                     System.out.println("The sustring is");
                     System.out.println(s7.substring(a, b));
                     test1 = "true";
                 }
             } while (test1.equals("false"));
             break;
    
         case 6:
             String test2;
             do {
                 System.out.println("enter College roll number");
                 String s8 = inp.next();
                 String s9 = s8.substring(0, 2);
                 String s10 = s8.substring(3, 4);
                 String s11 = s8.substring(4, 6);
                 if (s8.length() == 6) {
                     System.out.println(s8.replace(s9, "-Batch 20" + s9 + "-"));
                     System.out.println(s8.replace(s10, "-Computer-"));
                     System.out.println(s8.replace(s11, "-rollNo-"));
                     test2 = "true";
                 } else {
                     System.out.println("Invalid input");
                     test2 = "false";
                 }
             } while (test2.equals("false"));
    
             break;
    
         case 7:
             System.out.println("enter a string");
             String s12 = inp.next();
             System.out.println("enter the character or string to find its index");
             String s13 = inp.next();
             System.out.println(s12.indexOf(s13));
             break;
    
         case 8:
             System.out.println("enter a string");
             String s14 = inp.next();
             System.out.println("after trimmimg");
             System.out.println(s14.trim());
             break;
         default:
             System.out.println("Invalid choice");
             break;
     }
     System.out.println("Contine again?");
     cont = inp.next();
    

    } while (cont.equalsIgnoreCase("y"));

  }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package stringoperationfromuser;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author dell
  */
  public class StringOPerationFromUser {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {

    // TODO code application logic here
    String t1, t2, t, crn;
    int c;
    String check = "y";
    Scanner text = new Scanner(System.in);
    while (check.equalsIgnoreCase("y")) {
    System.out.println("enter your choice");
    System.out.println("1-string Concatinate\n2-string compare\n3- Touppercase\n4-CharAt\n5-substring\n6-Replace\n7-indexofChar\n8-trim");
    Scanner choice = new Scanner(System.in);
    c = choice.nextInt();
    switch (c) {
    case 1: {
    System.out.println("enter your first text for concatenation");
    t1 = text.next();
    System.out.println("enter your second text for concatenation");
    t2 = text.next();
    System.out.println(t1.concat(t2));
    }
    break;
    case 2:
    System.out.println("enter your first text for comparision");
    t1 = text.next();
    System.out.println("enter your second text for comparision");
    t2 = text.next();

             if (t1.equals(t2)) {
                 System.out.println("same text");
             } else {
                 System.out.println("different text");
             }
             break;
         case 3:
             System.out.println("enter your text to change into lower case ");
             t1 = text.next();
             System.out.println(t1.toLowerCase());
             System.out.println("enter your text to change into upper case ");
             t2 = text.next();
             System.out.println(t2.toUpperCase());
    
             break;
         case 4:
             System.out.println("enter your text");
             t = text.next();
             for (int i = 0; i < 5; i++) {
                 System.out.println(t.charAt(i));
             }
             System.out.println(StringUtils.capitalize(t.toLowerCase()));
             break;
         case 5:
             System.out.println("enter your text for substring eg:710340");
             int a,
              b;
             crn = text.next();
             System.out.println("enter the first digit");
             a = text.nextInt();
             System.out.println("enter the ending digit");
             b = text.nextInt();
             System.out.println(crn.substring(a, b));
             break;
    
         case 6:
             System.out.println("enter your text for replace");
             crn = text.next();
             String old,
              ne;
             System.out.println("enter the string you want to replace");
             old = text.next();
             System.out.println("enter the new value");
             ne = text.next();
             System.out.println(crn.replace(old, ne));
    
             break;
         case 7:
             System.out.println("enter your text");
             t1 = text.next();
             System.out.println("enter the character to find");
             t = text.next();
             System.out.println(t1.indexOf(t));
             break;
         case 8:
             System.out.println("enter your text with white space");
             t1 = text.next();
             System.out.println(t1.trim());
             break;
         default:
             System.out.println("invalid");
    
     }
     System.out.println("do yo want to continue?y\n\t");
     check = choice.next();
    

    }

  }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package day08task01;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author Samikshya
  */
  public class Day08Task01 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {

    String t1, t2, t, crn;
    int c;
    String check = "y";
    Scanner text = new Scanner(System.in);
    while (check.equalsIgnoreCase("y")) {
    System.out.println("enter your choice");
    System.out.println("1-string Concatinate\n2-string compare\n3- Touppercase\n4-CharAt\n5-substring\n6-Replace\n7-indexofChar\n8-trim");
    Scanner choice = new Scanner(System.in);
    c = choice.nextInt();
    switch (c) {
    case 1: {
    System.out.println("enter your first text for concatenation");
    t1 = text.next();
    System.out.println("enter your second text for concatenation");
    t2 = text.next();
    System.out.println(t1.concat(t2));
    }
    break;
    case 2:
    System.out.println("enter your first text for comparision");
    t1 = text.next();
    System.out.println("enter your second text for comparision");
    t2 = text.next();

             if (t1.equals(t2)) {
                 System.out.println("same text");
             } else {
                 System.out.println("different text");
             }
             break;
         case 3:
             System.out.println("enter your text to change into lower case ");
             t1 = text.next();
             System.out.println(t1.toLowerCase());
             System.out.println("enter your text to change into upper case ");
             t2 = text.next();
             System.out.println(t2.toUpperCase());
    
             break;
         case 4:
             System.out.println("enter your text");
             t = text.next();
             for (int i = 0; i < 5; i++) {
                 System.out.println(t.charAt(i));
             }
             System.out.println(StringUtils.capitalize(t.toLowerCase()));
             break;
         case 5:
             System.out.println("enter your roll no for substring eg:71033811");
             int a,
              b;
             crn = text.next();
             System.out.println("enter the first digit");
             a = text.nextInt();
             System.out.println("enter the ending digit");
             b = text.nextInt();
             System.out.println(crn.substring(a, b));
             break;
    
         case 6:
             System.out.println("enter your text for replace");
             crn = text.next();
             String old,
              ne;
             System.out.println("enter the string you want to replace");
             old = text.next();
             System.out.println("enter the new value");
             ne = text.next();
             System.out.println(crn.replace(old, ne));
    
             break;
         case 7:
             System.out.println("enter your text");
             t1 = text.next();
             System.out.println("enter the character to find");
             t = text.next();
             System.out.println(t1.indexOf(t));
             break;
         case 8:
             System.out.println("enter your text with white space");
             t1 = text.next();
             System.out.println(t1.trim());
             break;
         default:
             System.out.println("invalid");
    
     }
     System.out.println("do yo want to continue?y\n\t");
     check = choice.next();
    

    }
    }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package day8task_1;

import java.util.Scanner;

/**
*

• @author Anish
  */
  public class Day8Task_1 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    String l = "n";
    do {
    System.out.print("1: Concatination\n2: Comparision\n3: toUpperCase & toLowerCase\n4: charAT\n5: Substring\n6: Replace\n7: indexOf\n8: Trim\nEnter your choice: ");
    Scanner in = new Scanner(System.in), s = new Scanner(System.in);
    int ch = in.nextInt();
    System.out.print("Enter your string: ");
    String s2, s1 = s.nextLine();
    switch (ch) {
    case 1:
    System.out.print("Enter your second string: ");
    s2 = s.nextLine();
    System.out.println("The concatinated string is: " + s1 + s2);
    break;
    case 2:
    System.out.print("Enter your second string: ");
    s2 = s.nextLine();
    if (s1 == s2) {
    System.out.println("The strings are same");
    } else {
    System.out.println("The string are different");
    }
    break;
    case 3:
    System.out.println("The give string in upper case is:" + s1.toUpperCase());
    System.out.println("The give string in lower case is:" + s1.toLowerCase());
    break;
    case 4:
    System.out.println("The characters of the string are:");
    for (int i = 0; i < s1.length(); i++) {
    System.out.println(s1.charAt(i));
    }
    break;
    case 5:
    System.out.print("Enter start and end index of substring:");
    int st = in.nextInt(),
    ed = in.nextInt();
    System.out.println("The substring is:" + s1.substring(st, ed));
    break;
    case 6:
    System.out.print("Enter the string you want to replace:");
    String r = s.nextLine();
    System.out.print("Enter the string you want to replace with:");
    String rw = s.nextLine();
    System.out.println("The result is:" + s1.replace(r, rw));
    break;
    case 7:
    System.out.print("Enter search key:");
    s2 = s.nextLine();
    System.out.println("The index of search key is:" + s1.indexOf(s2));
    break;
    case 8:
    System.out.println("The trimmed string is:" + s1.trim());
    break;
    default:
    System.out.println("Invalid case");
    break;
    }
    System.out.println("Do you want to continue??(Y/N)");
    l = s.next();
    } while (l.equalsIgnoreCase("y"));
    }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package day8task10;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author kajal
  */
  public class Day8Task10 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    String s1, s2, t, crn;
    int c;
    String check = "y";
    Scanner text = new Scanner(System.in);
    while (check.equalsIgnoreCase("y")) {
    System.out.println("enter your choice");
    System.out.println("1-string Concatinate\n2-string compare\n3- Touppercase\n4-CharAt\n5-substring\n6-Replace\n7-indexofChar\n8-trim");
    Scanner choice = new Scanner(System.in);
    c = choice.nextInt();
    switch (c) {
    case 1: {
    System.out.println("enter your first text for concatenation");
    s1 = text.next();
    System.out.println("enter your second text for concatenation");
    s2 = text.next();

             System.out.println(s1.concat(s2));
             break;
         }
         case 2: {
             System.out.println("enter your first text for compare");
             s1 = text.next();
             System.out.println("enter your second text for compare");
             s2 = text.next();
    
             if (s1.equalsIgnoreCase(s2)) {
                 System.out.println("equal");
                 break;
             }
         }
         case 3: {
             System.out.println("enter your text");
             s1 = text.next();
             System.out.println(s1.toUpperCase());
             break;
         }
         case 4: {
             System.out.println("enter your 4text ");
             s1 = text.next();
             for (int i = 0; i < 5; i++) {
                 System.out.println(s1.charAt(i));
             }
             System.out.println(StringUtils.capitalize(s1.toLowerCase()));
             break;
         }
         case 5: {
             System.out.println("enter your text for substring eg:710331");
             int a, b;
             crn = text.next();
             System.out.println("enter the first digit");
             a = text.nextInt();
             System.out.println("enter the ending digit");
             b = text.nextInt();
             System.out.println(crn.substring(a, b));
             break;
    
         }
         case 6:
             System.out.println("enter your string for replace");
             crn = text.next();
             String old,
              new_;
             System.out.println("enter the string you want to replace");
             old = text.next();
             System.out.println("enter the new value");
             new_ = text.next();
             System.out.println(crn.replace(old, new_));
    
             break;
         case 7:
             System.out.println("enter your text");
             s1 = text.next();
             System.out.println("enter the character to find");
             t = text.next();
             System.out.println(s1.indexOf(t));
             break;
         case 8:
             System.out.println("enter your text with white space1");
             s1 = text.next();
             System.out.println(s1.trim());
             break;
         default:
             System.out.println("invalid");
    
     }
    
     System.out.println("\ndo yo want to continue?y\n\t");
     check = choice.next();
    

    }
    }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package d8c1;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author praben shaiju
  */
  public class D8c1 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    int a;
    Scanner input=new Scanner(System.in);

    System.out.println("Input the value\n1)string concatenation\n2)string comparision\n3)string casing\n4)capitalization\n5)get char indexing\n6)substring\n7)string replacing\n8)Index of char\n9)trim");
    a=input.nextInt();

    switch(a)
    {

      case 1:System.out.println("enter any 3 strings");
             String s1=input.next();
             String s2=input.next();
             String s3=input.next();
             System.out.println(s1+s2);
             System.out.println(s1.concat(s2));
             System.out.println(s1.concat(s2.concat(s3)));
             break;
    
      case 2:System.out.println("enter any 2 strings");
             String t1=input.next();
             String t2=input.next();
             if(t1.equalsIgnoreCase(t2))
             {
             System.out.println("success");
             }
              else
             {
              System.out.println("failure");
             }
             break;
    
    
      case 3:System.out.println("enter the string");
             String T1=input.next();
             System.out.println(T1.toUpperCase());
             System.out.println(T1.toLowerCase());
             System.out.println(T1);
             break;
    
    
      case 4:System.out.println("enter any string");
             String n=input.next();
             System.out.println(StringUtils.capitalize(n.toLowerCase()));
             break;
    
    
      case 5:System.out.println("enter any string");
             String np=input.next();
             System.out.println(np.charAt(3));
             break;
             
    
    
    
      case 6:System.out.println("enter your college roll number");
             String crn=input.next();
             System.out.println(crn.substring(2));
             System.out.println(crn.substring(3,5));
             break;
    
    
      case 7:System.out.println("enter your college roll number");
             String Crn=input.next();
             System.out.println(Crn.replace("71","batch 71"));
             System.out.println(Crn.replaceAll(Crn, "0710319"));
             System.out.println(Crn);
             break;
    
    
      case 8:System.out.println("enter any string");
             String t="test";
             System.out.println(t.indexOf('t'));
             System.out.println(t.lastIndexOf('t'));
             System.out.println(t.indexOf("st"));
             break;
             
             
      case 9:System.out.println("enter any string");
             String p=input.next();
             System.out.println(p.trim());
             break;
             
      default:System.out.println("invalid input");
    

    }
    // TODO code application logic here
    }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package assignment;

import java.util.Scanner;
import static jdk.nashorn.tools.ShellFunctions.input;

/**
*

• @author DELL
  */
  public class Assignment {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    Scanner input = new Scanner(System.in);
    Scanner st = new Scanner(System.in);
    int n;
    String s1, s2;
    String check = "y";
    while (check.equalsIgnoreCase("y")) {
    System.out.println("Enter The choice : \n 1.Concatination\n 2.Comparison\n 3.To Uppercase or Lowercase\n 4.charAt\n 5.Substring\n 6.Replace\n 7.IndexofChar\n 8.Trim");
    n = input.nextInt();
    switch (n) {
    case 1: {
    System.out.println("Enter First string : ");
    s1 = st.next();
    System.out.println("Enter Second string : ");
    s2 = st.next();
    System.out.println(s1.concat(s2));
    break;
    }
    case 2: {
    System.out.println("Enter First string : ");
    s1 = st.next();
    System.out.println("Enter Second string : ");
    s2 = st.next();

             if (s1.equalsIgnoreCase(s2)) {
                 System.out.println("Equal");
    
             } else {
                 System.out.println("Not equal");
             }
             break;
    
         }
    
         case 3: {
             System.out.println("Enter your string : ");
             s1 = st.next();
             System.out.println("Uppercase : " + s1.toUpperCase());
             System.out.println("Lowercase : " + s1.toLowerCase());
             break;
    
         }
    
         case 4: {
             System.out.println("Enter your string : ");
             s1 = st.next();
             for (int i = 0; i < 5; i++) {
    
                 System.out.println(s1.charAt(i));
             }
             break;
    
         }
    
         case 5: {
             System.out.println("Enter your college roll no : ");
             s1 = st.next();
             System.out.println(s1.substring(0, 2));
             System.out.println(s1.substring(3, 4));
             System.out.println(s1.substring(4, 6));
             System.out.println(s1.replace("71", "Batch 2077 "));
             System.out.println(s1.replace("03", "Computer"));
             break;
    
         }
    
         case 6: {
             System.out.println("Enter your college year : ");
             s1 = st.next();
             System.out.println(s1.replace("71", "Year 20" + s1));
             break;
    
         }
         case 7: {
             System.out.println("enter your text");
             s1 = st.next();
             System.out.println("enter the character to find");
             s2 = st.next();
             System.out.println(s1.indexOf(s2));
             break;
         }
    
         case 8: {
             System.out.println("Enter the string with space");
             s1 = st.next();
             System.out.println(s1.trim());
             break;
         }
         default: {
             System.out.println("Invalid input!!!");
    
         }
    
     }
     System.out.println("Would you like to continue?(y-n) \t");
    
     check = input.next();
    

    }
    }

}

OUTPUT

from java.

package stringop;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author Lenovo
  */
  public class StringOp {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    Scanner in = new Scanner(System.in);
    Scanner inp = new Scanner(System.in);

    String S1, S2, check = "y";
    System.out.println("Enter the strings S1");
    S1 = in.nextLine();
    System.out.println("Enter the next string S2");
    S2 = in.nextLine();
    do {
    System.out.println("Enter the choices");
    System.out.print("1. Concatenation\n2. Comparison\n3. Uppercase and lowercase\n4. CharAt(index)\n5. Substring\n6. Replace\n7. IndexOf(char)\n8. Trim\n");
    int choice;
    choice = inp.nextInt();
    switch (choice) {
    case 1:
    System.out.println("After Concatinating");
    System.out.println(S1 + S2);
    System.out.println(S1.concat(S2));
    break;
    case 2:
    System.out.println("After Comparing");
    if (S1.equals(S2)) {
    System.out.println("the strings are equal");
    } else {
    System.out.println("strings are unequal");
    }
    break;
    case 3:
    System.out.println("into Uppercase and lowercase");
    System.out.println(S1.toUpperCase());
    System.out.println(S2.toLowerCase());
    System.out.println(StringUtils.capitalize(S1));
    System.out.println(StringUtils.decapitalize(S2));
    break;
    case 4:
    System.out.println("Characterwise listing");
    for (int i = 0; i < S1.length(); i++) {
    System.out.println(S1.charAt(i));
    }
    break;
    case 5:
    System.out.println("Substrings");
    System.out.println(S1.substring(0, 3));
    System.out.println(S1.substring(4, 6));
    System.out.println(S1.substring(5, 8));
    break;
    case 6:
    System.out.println("After replacing");
    System.out.println(S1.replace("s", "sweet"));
    System.out.println(S1.replace("d", "danger"));
    System.out.println(S1.replace("ha", "hahaha"));
    break;
    case 7:
    System.out.println("index of");
    System.out.println(S1.indexOf("s"));
    System.out.println(S1.indexOf("a"));
    System.out.println(S1.lastIndexOf("d"));
    System.out.println(S1.indexOf("ddha"));
    break;
    case 8:
    System.out.println("After trimming");
    System.out.println(S1.trim());
    break;
    default:
    System.out.println("invalid input");
    break;
    }
    System.out.println("Do you want to continue? (y/n)");
    check = in.next();
    } while (check.equalsIgnoreCase("y"));
    }
    }
    
    
    
    
    

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package ass.day8;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author nissus
  */
  public class AssDay8 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    String s1,s2,s3,crn;
    System.out.println("1.Concatenation");
    System.out.println("2.Comparison");
    System.out.println("3.toUpperCase");
    System.out.println("4.toLowerCase");
    System.out.println("5.Capitalize");
    System.out.println("6.charAt(index)");
    System.out.println("7.Substring");
    System.out.println("8.Replace");
    System.out.println("9.IndexOf(char),lastIndexOf(char)");
    System.out.println("10.trim()");
    System.out.println("Enter your choice");

    String check="y";
    while (check.equalsIgnoreCase(check)){
    Scanner input=new Scanner(System.in);
    int n=input.nextInt();
    switch(n){
    case 1:
    System.out.println("Enter first string to concatenate");
    input=new Scanner(System.in);
    s1=input.nextLine();
    System.out.println("Enter second string to concatenate");

         input=new Scanner(System.in);
         s2=input.nextLine();
         System.out.println("Enter third string to concatenate");
         input=new Scanner(System.in);
         s3=input.nextLine();
         System.out.println(s1.concat(s2.concat(s3)));
    
     break;
     case 2:
          System.out.println("Enter first string to compare");
         input=new Scanner(System.in);
         s1=input.nextLine();
         System.out.println("Enter second string to compare");
         
         input=new Scanner(System.in);
         s2=input.nextLine();
         if(s1.equalsIgnoreCase(s2)){
    System.out.println("Equal");}
    else{
            System.out.println("Not Equal");
            }
    break;
     case 3:
          System.out.println("Enter string for UPPERCASE");
         input=new Scanner(System.in);
         s1=input.nextLine(); 
         System.out.println(s1.toUpperCase());
     break;
     case 4:
          System.out.println("Enter string for lowercase");
         input=new Scanner(System.in);
         s1=input.nextLine(); 
         System.out.println(s1.toLowerCase());
         break;
     case 5:
         System.out.println("Enter string to Capitalize");
         input=new Scanner(System.in);
         s1=input.nextLine(); 
         System.out.println(StringUtils.capitalize(s1.toLowerCase()));
         break;
     case 6:
         System.out.println("Enter string");
         input=new Scanner(System.in);
         s1=input.nextLine(); 
         int s=s1.length();
         for (int i = 0; i < s; i++) 
             {
             System.out.println(s1.charAt(i));   
             }
     break;
     case 7:
         System.out.println("Enter string");
         input=new Scanner(System.in);
         crn=input.nextLine();
         System.out.println(crn.substring(0,2));
         System.out.println(crn.substring(3,4));
         System.out.println(crn.substring(4,6));
     break;
     case 8:
         crn="660346";
          System.out.println(crn.replace("66","Batch 2066_"));
         System.out.println(crn.replace("03","_Computer"));
     break;
     case 9:
         s1="test";
                 
         System.out.println(s1.indexOf('t'));
         System.out.println(s1.lastIndexOf('t'));
         System.out.println(s1.indexOf("est"));
     break;
     case 10:
         System.out.println("Enter string with spaces");
         input=new Scanner(System.in);
         crn=input.nextLine();
         System.out.println(crn.trim());
    

    }
    System.out.println("Do you want to continue");
    check=input.next();
    }
    // TODO code application logic here
    }

}

from java.

public static void main(String[] args) {
// TODO code application logic here
Scanner in = new Scanner(System.in);
String s1, s2, s3, s4, s5;
String check = "y";
while (check.equalsIgnoreCase("y")) {
System.out.print("enter ur choice\n"
+ "1:concatination\n"
+ "2:comparison\n"
+ "3:uppercae\n"
+ "4:lowercase\n"
+ "5index\n"
+ "6:substring\n"
+ "7:replace\n"
+ "8:indexof\n"
+ "9:trim\n");
int x = in.nextInt();
switch (x) {
case 1:
System.out.println("enter 1st string");
s1 = in.next();
System.out.println("2nd string");
s2 = in.next();
System.out.println("output:" + s1 + s2);
break;

            case 2:
                System.out.println("enter 1st string");
                s1 = in.next();
                System.out.println("2nd string");
                s2 = in.next();
                if (s1.equals(s2)) {
                    System.out.println("true");
                } else {
                    System.out.println("false");
                }
                break;

            case 3:
                System.out.println("enter string for uppercase");
                s3 = in.next();
                System.out.println(s3.toUpperCase());
                break;
            case 4:
                System.out.println("enter string for lowerrcase");
                s3 = in.next();
                System.out.println(s3.toLowerCase());
                break;
            case 5:
                System.out.println("enter string");
                s4 = in.next();
                System.out.println(StringUtils.capitalize(s4.toLowerCase()));
                break;
            case 6:
                System.out.println("enter substring  ");
                s4 = in.next();
                System.out.println("enter start number");
                int c = in.nextInt();
                System.out.println("enter end number");
                int p = in.nextInt();
                System.out.println("output:" + s4.substring(c, p));
                break;

            case 7:
                System.out.println("enter string");
                s3 = in.next();
                System.out.println(s3);
                System.out.println("enter string u want replace");
                s2 = in.next();
                System.out.println(" to replace string ");
                s4 = in.next();
                System.out.println("output:" + s3.replace(s2, s4));
                break;

            case 8:
                System.out.println("enter your text");
                s1 = in.next();
                System.out.println("enter the character to find");
                s2 = in.next();
                System.out.println(s1.indexOf(s2));
                break;

            case 9:
                System.out.println("enter your text with  space");
                s1 = in.next();
                System.out.println(s1.trim());
                break;
            default:
                System.out.println("wrong input");
        }

        System.out.println("\ndo yo want to continue?y\n\t");
        check = in.next();
    }
}

}

from java.

CRN: 660303
After Replacing...
66Computer Computer - This is not good

Try to replace only department code by department name.

from java.

Run replace section of @Sudan15423 & optimize it.
@bsnarnzt1 also did that, so optimize & manage user interaction of her code.

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package javaapplication72;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author Kishorr
  */
  public class JavaApplication72 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    int no;
    Scanner input = new Scanner(System.in);
    String s1, s2, s3;
    System.out.println("Enter First String");
    s1 = input.next();
    System.out.println("Enter Second String");
    s2 = input.next();
    System.out.println("Enter Third String");
    s3 = input.next();
    String crn = "710322";
    String s4 = "test", s5 = "Test";

    System.out.println("enter your choice");
    System.out.println("1. Concatenation");
    System.out.println("2. Comparison");
    System.out.println("3. toUpperCase, toLowerCase");
    System.out.println("4. charAt(index)");
    System.out.println("5. Substring");
    System.out.println("6. Replace");
    System.out.println("7. indexOf(char)");
    System.out.println("8. trim");

    no = input.nextInt();
    switch (no) {
    case 1:
    System.out.println(s1 + s2);
    System.out.println(s1.concat(s2));
    System.out.println(s1.concat(s2.concat(s3)));
    break;

     case 2:
    
         if (s4.equalsIgnoreCase(s5)) {
             System.out.println("Equal");
         }
         break;
    
     case 3:
         System.out.println(s4.toUpperCase());
         System.out.println(s4.toLowerCase());
         System.out.println(StringUtils.capitalize(s4.toLowerCase()));
         break;
    
     case 4:
         for (int i = 0; i < s5.length(); i++) {
             System.out.println(s5.charAt(i));
         }
         break;
    
     case 5:
         System.out.println("Rollno" + crn);
         System.out.println("Batch is" + crn.substring(0, 2));
         System.out.println("Department is" + crn.substring(3, 4));
         System.out.println("Roll is" + crn.substring(4, 6));
         break;
    
     case 6:
         System.out.println(crn.replace("71", "Batch 71"));
         break;
    
     case 7:
         String s = "rabin";
         System.out.println(s.indexOf('r'));
         System.out.println(s.lastIndexOf('r'));
         System.out.println(s.lastIndexOf("in"));
    
     case 8:
         String nl = "       Nepal         ";
         System.out.println(nl.trim());
         break;
    
     default:
         System.out.println("Invalid Choice");
    

    }
    }

}

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package batchdptroll;

import com.sun.org.apache.bcel.internal.generic.GOTO;
import java.util.Scanner;
import java.util.regex.Pattern;

/**
*

• @author ragen
  */
  public class BatchDptRoll {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {

    String s,dept,batch,roll,dept_name;

    start:
    System.out.println("Enter yOur College ID(6-digit)");
    Scanner scanner = new Scanner(System.in);
    String Col_roll = scanner.nextLine();
    s=Col_roll;
    int len=s.length();
    if(Pattern.matches("[a-zA-Z]+", s) == true || len > 6)
    {
    System.out.println("Your enter Wrong Roll number");

           }
           else{
           dept=s.substring(2,4);     
            //for (int i = 0; i < len; i++) {
             //  char s2=s.charAt(i);
            if (dept.equals("01")) {
      dept_name = "Civil Engineering";
    

    } else if (dept.equals("02")) {
    dept_name = "Architecture";
    } else if (dept.equals("03")) {
    dept_name = "Computer Engineering";
    } else if (dept.equals("04")) {
    dept_name = "Electronics Engineering";
    } else {
    dept_name = "No Such Department";
    }
    System.out.println("Batch: 20" + s.substring(0, 2));
    System.out.println("Department: " + dept_name);
    System.out.println("Rollno.: " + s.substring(4, 6));

                   }
    
           }
    

  }

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package stringoperationusingswitch;

import com.sun.xml.internal.ws.util.StringUtils;
import static java.lang.Integer.parseInt;
import static java.time.Clock.system;
import java.util.Scanner;
import javax.swing.JOptionPane;

/**
*

• @author ragen
  */
  public class StringOperationUsingSwitch {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    int choice;
    String s1,s=" Nepa l ";//string itself a class
    String s2,s3;

    choice=parseInt(JOptionPane.showInputDialog(""
    + "Enter your Choice!!\n"
    + "1.Concatenation\n"
    + "2. comparison\n"
    + "3. toUppercase\n"
    + "4. charAt\n"
    + "5. Substring\n"
    + "6. Replace\n"
    + "7. IndexOf\n"
    + "8. Trim()"));
    switch(choice){
    case 1:

            /* s1=JOptionPane.showInputDialog("Enter First String");
             s2= JOptionPane.showInputDialog("Enter Second String");
             s3= JOptionPane.showInputDialog("Enter Third String");
             *//*
             Scanner in=new Scanner(System.in);
             System.out.println("age");
             int age=in.nextInt();
                               //System.out.println(age);
    

*/
System.out.println("Enter First String ");
Scanner scanner = new Scanner(System.in);
String str1 = scanner.nextLine();
System.out.println("Your First String is " + str1);
System.out.println("Enter Second String ");
String str2 = scanner.nextLine();
System.out.println("Your Second String is " + str2);
System.out.println("Enter Third String ");
String str3 = scanner.nextLine();
System.out.println("Your Third String is " + str3);

                s1=str1;
               s2=str2;
               s3=str3;
                System.out.println(s1+s2+s3);
                System.out.println(s1.concat(s2));
                System.out.println(s1.concat(s2.concat(s3)));
                break;
          case 2:
                  System.out.println("Enter First String ");
                Scanner scann = new Scanner(System.in);
                String st1 = scann.nextLine(); 
                System.out.println("Your First String is " + st1);
                System.out.println("Enter Second String ");
                String st2 = scann.nextLine(); 
                System.out.println("Your Second String is " + st2);
                 System.out.println("Enter Third String ");
                String st3 = scann.nextLine(); 
                System.out.println("Your Third String is " + st3);
                
                s1=st1;
                s2=st2;
                s3=st3;
               System.out.println(s1.equals(s2));
                System.out.println(s1.equalsIgnoreCase(s2));
    if(s1==s2)
    {
        System.out.println("Equal");
    }
    else{
    
        System.out.println("Not  Equal");}
    if(s1.equals(s3)){
        System.out.println("Right");
    }
    else{
        System.out.println("Wrong");
    }
               break;
          case 3:
                System.out.println("Enter First String ");
                Scanner scan = new Scanner(System.in);
                String stt1 = scan.nextLine(); 
                System.out.println("Your First String is " + stt1);
                s1=stt1;
                System.out.println(s1.toUpperCase());
    System.out.println(s1.toLowerCase());
    break;
          case 4:
              System.out.println("Enter First String ");
                Scanner scan1 = new Scanner(System.in);
                String st = scan1.nextLine(); 
                System.out.println("Your First String is " + st);
                s1=st;
                
               for (int i = 0; i < s1.length(); i++) {
    System.out.println(s1.charAt(i));
    }
         System.out.println(StringUtils.capitalize(s1.toLowerCase()));
   break;
          case 5:  
                      System.out.println("Enter First String ");
                Scanner scannn = new Scanner(System.in);
                String strt1 = scannn.nextLine(); 
                System.out.println("Your First String is " + strt1);
                s3=strt1;
                
                      System.out.println(s3.substring(0,2));
                      System.out.println(s3.substring(4,2));
          break;
          case 6:
                  System.out.println("Enter First String ");
                Scanner scannnn = new Scanner(System.in);
                String strit1 = scannnn.nextLine(); 
                System.out.println("Your First String is " + strit1);
                s3=strit1;
               System.out.println(s3.replace("20", "Twenty"));
   
              break;
          case 7:
                System.out.println("Enter First String ");
                Scanner scaner = new Scanner(System.in);
                String strin1 = scaner.nextLine(); 
                System.out.println("Your First String is " + strin1);
                s1=strin1;
               System.out.println(s1.indexOf('N'));
               System.out.println(s1.lastIndexOf('L'));
   
              break;
          case 8:
                System.out.println("Enter First String ");
                Scanner scannner = new Scanner(System.in);
                String string1 = scannner.nextLine(); 
                System.out.println("Your First String is " + string1);
                s1=string1;
               
                System.out.println(s1.trim());
              break;
      }

}

}

from java.

package string.operation;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author PC
  */
  public class StringOperation {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    String t1, t2, t, crn;
    int c;
    String check = "y";
    Scanner text = new Scanner(System.in);
    while (check.equalsIgnoreCase("y")) {
    System.out.println("enter your choice");
    System.out.println("1-string Concatinate\n2-string compare\n3- Touppercase\n4-CharAt\n5-substring\n6-Replace\n7-indexofChar\n8-trim");
    Scanner choice = new Scanner(System.in);
    c = choice.nextInt();
    switch (c) {
    case 1: {
    System.out.println("enter your first text for concatenation");
    t1 = text.next();
    System.out.println("enter your second text for concatenation");
    t2 = text.next();
    System.out.println(t1.concat(t2));
    }
    break;
    case 2:
    System.out.println("enter your first text for comparision");
    t1 = text.next();
    System.out.println("enter your second text for comparision");
    t2 = text.next();

             if (t1.equals(t2)) {
                 System.out.println("same text");
             } else {
                 System.out.println("different text");
             }
             break;
         case 3:
             System.out.println("enter your text to change into lower case ");
             t1 = text.next();
             System.out.println(t1.toLowerCase());
             System.out.println("enter your text to change into upper case ");
             t2 = text.next();
             System.out.println(t2.toUpperCase());
    
             break;
         case 4:
             System.out.println("enter your text");
             t = text.next();
             for (int i = 0; i < 5; i++) {
                 System.out.println(t.charAt(i));
             }
             System.out.println(StringUtils.capitalize(t.toLowerCase()));
             break;
         case 5:
             System.out.println("enter your text for substring eg:710309");
             int a,
              b;
             crn = text.next();
             System.out.println("enter the first digit");
             a = text.nextInt();
             System.out.println("enter the ending digit");
             b = text.nextInt();
             System.out.println(crn.substring(a, b));
             break;
    
         case 6:
             System.out.println("enter your text for replace");
             crn = text.next();
             String old,
              ne;
             System.out.println("enter the string you want to replace");
             old = text.next();
             System.out.println("enter the new value");
             ne = text.next();
             System.out.println(crn.replace(old, ne));
    
             break;
         case 7:
             System.out.println("enter your text");
             t1 = text.next();
             System.out.println("enter the character to find");
             t = text.next();
             System.out.println(t1.indexOf(t));
             break;
         case 8:
             System.out.println("enter your text with white space");
             t1 = text.next();
             System.out.println(t1.trim());
             break;
         default:
             System.out.println("invalid");
    
     }
     System.out.println("do yo want to continue?y\n\t");
     check = choice.next();
    

    }

  }

}

from java.

package string.operation;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author PC
  */
  public class StringOperation {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    // TODO code application logic here
    String t1, t2, t, crn;
    int c;
    String check = "y";
    Scanner text = new Scanner(System.in);
    while (check.equalsIgnoreCase("y")) {
    System.out.println("enter your choice");
    System.out.println("1-string Concatinate\n2-string compare\n3- Touppercase\n4-CharAt\n5-substring\n6-Replace\n7-indexofChar\n8-trim");
    Scanner choice = new Scanner(System.in);
    c = choice.nextInt();
    switch (c) {
    case 1: {
    System.out.println("enter your first text for concatenation");
    t1 = text.next();
    System.out.println("enter your second text for concatenation");
    t2 = text.next();
    System.out.println(t1.concat(t2));
    }
    break;
    case 2:
    System.out.println("enter your first text for comparision");
    t1 = text.next();
    System.out.println("enter your second text for comparision");
    t2 = text.next();

             if (t1.equals(t2)) {
                 System.out.println("same text");
             } else {
                 System.out.println("different text");
             }
             break;
         case 3:
             System.out.println("enter your text to change into lower case ");
             t1 = text.next();
             System.out.println(t1.toLowerCase());
             System.out.println("enter your text to change into upper case ");
             t2 = text.next();
             System.out.println(t2.toUpperCase());
    
             break;
         case 4:
             System.out.println("enter your text");
             t = text.next();
             for (int i = 0; i < 5; i++) {
                 System.out.println(t.charAt(i));
             }
             System.out.println(StringUtils.capitalize(t.toLowerCase()));
             break;
         case 5:
             System.out.println("enter your text for substring eg:710309");
             int a,
              b;
             crn = text.next();
             System.out.println("enter the first digit");
             a = text.nextInt();
             System.out.println("enter the ending digit");
             b = text.nextInt();
             System.out.println(crn.substring(a, b));
             break;
    
         case 6:
             System.out.println("enter your text for replace");
             crn = text.next();
             String old,
              ne;
             System.out.println("enter the string you want to replace");
             old = text.next();
             System.out.println("enter the new value");
             ne = text.next();
             System.out.println(crn.replace(old, ne));
    
             break;
         case 7:
             System.out.println("enter your text");
             t1 = text.next();
             System.out.println("enter the character to find");
             t = text.next();
             System.out.println(t1.indexOf(t));
             break;
         case 8:
             System.out.println("enter your text with white space");
             t1 = text.next();
             System.out.println(t1.trim());
             break;
         default:
             System.out.println("invalid");
    
     }
     System.out.println("do yo want to continue?y\n\t");
     check = choice.next();
    

    }

  }

}

from java.

CODE:
package stringoperation;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author User
  */
  public class StringOperation {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {

Scanner in = new Scanner(System.in);
Scanner inp = new Scanner(System.in);

String S1, S2, check = "y";
System.out.println("Enter the strings S1");
S1 = in.nextLine();
System.out.println("Enter the next string S2");
S2 = in.nextLine();
do {
System.out.println("Enter the choices");
System.out.print("1. Concatenation\n2. Comparison\n3. Uppercase and lowercase\n4. CharAt(index)\n5. Substring\n6. Replace\n7. IndexOf(char)\n8. Trim\n");
int choice;
choice = inp.nextInt();
switch (choice) {

case 1:
System.out.println("After Concatinating");
System.out.println(S1 + S2);
System.out.println(S1.concat(S2));
break;

case 2:
System.out.println("After Comparing");
if (S1.equals(S2)) {
System.out.println("the strings are equal");
} else {
System.out.println("strings are unequal");
}
break;

case 3:
System.out.println("into Uppercase and lowercase");
System.out.println(S1.toUpperCase());
System.out.println(S2.toLowerCase());
System.out.println(StringUtils.capitalize(S1));
System.out.println(StringUtils.decapitalize(S2));
break;

case 4:
System.out.println("Characterwise listing");
for (int i = 0; i < S1.length(); i++) {
System.out.println(S1.charAt(i));
}
break;

case 5:
System.out.println("Substrings");
System.out.println(S1.substring(0, 3));
System.out.println(S1.substring(4, 6));
System.out.println(S1.substring(5, 8));
break;

case 6:
System.out.println("After replacing");
System.out.println(S1.replace("s", "sweet"));
System.out.println(S1.replace("d", "danger"));
System.out.println(S1.replace("ha", "hahaha"));
break;

case 7:
System.out.println("index of");
System.out.println(S1.indexOf("s"));
System.out.println(S1.indexOf("a"));
System.out.println(S1.lastIndexOf("d"));
System.out.println(S1.indexOf("ddha"));
break;

case 8:
System.out.println("After trimming");
System.out.println(S1.trim());
break;
default:
System.out.println("invalid input");
break;
}
System.out.println("Do you want to continue? (y/n)");
check = in.next();
} while (check.equalsIgnoreCase("y"));
}
}
Output:

from java.

/*

• To change this license header, choose License Headers in Project Properties.
• To change this template file, choose Tools | Templates
• and open the template in the editor.
  */
  package task2;

import com.sun.xml.internal.ws.util.StringUtils;
import java.util.Scanner;

/**
*

• @author admin
  */
  public class Task2 {

  /**

  • @param args the command line arguments
    */
    public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    int choice;
    System.out.println("Enter the operation 1.concatination\t 2.comparision\t 3. toupperCase/toLowerCase 4.charAt\t 5.substring\t6.replace\t 7.indexOf\t 8.trim");
    choice = input.nextInt();
    switch (choice) {
    case 1: {
    // System.out.println("CONCATINATION");

         String s1, s2, s3;
         System.out.println("enter first string");
         s1 = input.next();
         System.out.println("enter 2nd string");
         s2 = input.next();
         System.out.println("enter 3rd string");
         s3 = input.next();
    
         System.out.println(s1 + s2);
         System.out.println(s1.concat(s2.concat(s3)));
         System.out.println(s1.concat(s2));
    
     }
     break;
     case 2: {
         String s1, s2;
         System.out.println("enter first string");
         s1 = input.next();
         System.out.println("enter 2nd string");
         s2 = input.next();
    
         if (s1.equals(s2)) {
             System.out.println("return false");
         }
         if (s1.equalsIgnoreCase(s2)) {
             System.out.println("return true");
         }
    
     }
     break;
     case 3: {
         String s;
         System.out.println("enter  string");
         s = input.next();
    
         System.out.println(s.toUpperCase());
         System.out.println(s.toLowerCase());
         break;
     }
    
     case 4: {
    
         String np;
         System.out.println("enter  string");
         np = input.next();
    
         for (int i = 0; i < np.length(); i++) {
    
             System.out.println(np.charAt(i));
             System.out.println(StringUtils.capitalize(np.toLowerCase()));
    
         }
    
     }
     break;
     case 5: {
         String crn;
         System.out.println("enter crn");
         crn = input.next();
    
         System.out.println(crn.substring(0, 2));
         System.out.println(crn.substring(3, 4));
         System.out.println(crn.substring(4, 6));
    
     }
     break;
    
     case 6: {
    
         String crn;
         System.out.println("enter crn");
         crn = input.next();
         System.out.println(crn.replace("66", "Batch 2066"));
         System.out.println(crn.replace("03", "Computer"));
    
     }
     break;
    
     case 7: {
         String s;
         System.out.println("enter string");
         s = input.next();
         System.out.println(s.indexOf('t'));
         System.out.println(s.lastIndexOf('t'));
         System.out.println(s.indexOf("est"));
    
     }
     break;
     case 8: {
    
         String s;
         System.out.println("enter string to trim");
         s = input.next();
         System.out.println(s.trim());
     }
     break;
    

    }

  }

}

from java.