Problem Set 4 challenges your ability to use (primarily) the String class and (to a lesser extent) the Math class. It is also the first problem set where, rather than printing output to the console, you'll be returning values from your methods.

To get started, you'll need to create a GitHub repository to store your Problem Set 4 code. After cloning my skeleton repository, you'll need to setup a remote to push your code to your repository instead of mine. Steps to accomplish this are outlined below.

1. Login to your GitHub account and create a new repository named problem-set-4.
2. In GitBash, navigate to your APCSA folder.

cd ~/Desktop/APCSA

3. Clone my skeleton repository from GitHub. This will make a copy of my repository and store it locally.

git clone [email protected]:rwilson-ucvts/java-pset-4-skeleton.git

4. The cloning process will have created a folder named java-pset-4-skeleton. Rename this folder to pset4.

mv java-pset-4-skeleton pset4

5. Change directories to get into your pset4 folder.

cd pset4

6. Originally, the remote will be pointing at my repository. We need to overwrite this.

git remote rename origin upstream

7. Lastly, we need to add a new remote that points at the repository you created earlier. Make sure you replace YOUR-USERNAME with your actual username.

git remote add origin [email protected]:YOUR-USERNAME/problem-set-4.git

8. Launch Eclipse and set the Workspace to the APCSA folder you created on your Desktop. Make sure you're using your Workspace, as others' will be similarly named.
9. From within the Package Explorer (the left-most panel), right-click and select Import....
10. Select Git > Projects from Git, and click Next >.
11. Select Existing local repository and click Next >.
12. Click the Add... button, and then the Browse... button.
13. Navigate to the APCSA folder on your Desktop, click the pset4 project folder, and click Open.
14. Select the checkbox next to your project and click Finish.
15. Now that we've imported the Git project, we can click Next >, Next >, and Finish once more.

You should now see a Project in the Package Explorer in Eclipse.

16. Expand the Project folder. You should see the JRE System Library folder, as well as the src folder.
17. Expand the src folder. You should see a single source file named ProblemSet4.java. Double-click to open it.

Problem Set 4 contains 10 exercises, each of which will be written in separate methods. The main method has already been declared for you, but you'll need to implement most of it. You'll also need to declare and implement each of the 10 exercise methods. The specifications for this are included in this README.md file, as well as in comments within the ProblemSet4.java file.

surroundMe shoud be a publicly available method that accepts a pair of Strings as input, and returns a String as output.

Given two Strings, outand in, return a new String built by surrounding in with the first and last two characters of out. Return null if the following specifcations are not met.

• out and in must not be null
• out must be exactly 4 characters
• in must be exactly 3 characters

surroundMe("<<>>", "abc") returns <<abc>>
surroundMe("[[]]", "xyz") returns [[xyz]]
surroundMe("abc", "abc") returns null
surroundMe("(())", "qwerty") returns null
surroundMe(null, "abc") returns null
surroundMe("<<>>", null) returns null

endsMeet shoud be a publicly available method that accepts a String and an int as input, and returns a String as output.

Given a String, str, and an int, n, return a new String built by combining the first n and last n characters of str. Return null if the following specifcations are not met.

• str must not be null
• str must be between 1 and 10 characters (inclusive)
• n must be a positive integer between 1 and the length of str (inclusive)

endsMeet("qwerty", 2) returns qwty
endsMeet("basketball", 3) returns basall
endsMeet("qwerty", -1) returns null
endsMeet("basketball", 0) returns null
endsMeet("qwerty", 9) returns null
endsMeet("programming", 2) returns null
endsMeet(null, 1) returns null

middleMan shoud be a publicly available method that accepts a String as input, and returns a String as output.

Given a String, str, return a new 3-character String built from the 3 middle characters of str. Return null if the following specifications are not met.

• str must not be null
• the lenght of str must be odd

middleMan("candy") returns and
middleMan("programming") returns ram
middleMan("even") returns null
middleMan(null) returns null

doubleVision shoud be a publicly available method that accepts a String as input, and returns a String as output.

Given a String, str, return a new String built from duplicating every character in str. Return null if the following specifcations are not met.

• str must not be null

doubleVision("qwerty") returns qqwweerrttyy
doubleVision("a") returns aa
doubleVision(null) returns null

centered shoud be a publicly available method that accepts a pair of Strings as input, and returns a boolean as output.

Given two Strings, str and target, determine whether or not target is in the middle of str. target will be considered in the middle of str if the number of characters to its left and right differ by 0 or 1. Return false if the following specifcations are not met.

• str and target must not be null
• target must be exactly 3 characters

centered("candy", "and") returns true
centered("programming", "ram") returns true
centered("qwerty", "qwe") returns false
centered("qwerty", "er") returns false
centered("qwerty", null) returns false
centered(null, "abc") returns false
centered(null, null) returns false

upOrDown shoud be a publicly available method that accepts a double and a char as input, and returns an int as output.

Given a decimal value, number, and a character, operation (representing either round, r, floor, f, or ceiling, c), return the result of the operation as an integer. Return -1 if the following specifcations are not met.

• operation is not within the set [r, f, c]

upOrDown(12.7, 'r') returns 13
upOrDown(12.2, 'r') returns 12
upOrDown(12.7, 'f') returns 12
upOrDown(12.2, 'c') returns 13
upOrDown(12.7, 'x') returns -1

countMe shoud be a publicly available method that accepts a String and a char as input, and returns an int as output.

Given a String, text, and a character, end, count and return the number of words in text that end with end. For our purposes, the end of a word will be defined as an alphabetic character followed by a whitespace character (i.e., a space, tab, or line break) or no character at all (i.e., the end of the String). Return -1 if the following specifcations are not met.

• text must not be null
• end must be in the set [Aa-Zz]

countMe("these are just some sample words", 'e') returns 3
countMe(null, 'n') returns -1
countMe("and some more sample words", '+') returns -1
countMe("one more batch of sample words", 'h') returns 1

isNotEqual shoud be a publicly available method that accepts a String as input, and returns a boolean as output.

Given a String, str, determine whether the number of case-sensitive appearances of the word is equals the number of case-sensitive appearances of the word not. Return false if the following specifcations are not met.

• str must not be null

isNotEqual("is not is not is") returns false
isNotEqual("is not is not is not") returns true
isNotEqual(null) returns false

triplets shoud be a publicly available method that accepts a String as input, and returns an int as output.

Given a String, str, return the number of triplets. A triplet is defined as a sequence of 3 identical characters in a row. Triplets are case-sensitive, meaning AAa is not triplet. Triplets can also overlap, meanning AAAA counts as 2 triplets. Return -1 if the following specifcations are not met.

• str must not be null
• str must not contain whitespace or non-alphabetic characters

triplets("abbbccccd") returns 3
triplets("aaabbbbccccc") returns 6
triplets(null) returns -1
triplets("abbb1ccc") returns -1
triplets("aaa bbb") returns -1

addMe shoud be a publicly available method that accepts a String and a boolean as input, and returns an int as output.

Given a String, str, compute and return either the sum of the digits or the sum of the numbers contained within str. If digits is true, then sum the digits individually. If it is false, sum the numbers. A number is defined as a 1 or more consecutive digits in str. Return -1 if the following specifcations are not met.

• str must not be null
• str must not contain whitespace characters

addme("a123b456c789", true) returns 45
addMe("a123b456c789", false) returns 1368
addMe(null) returns -1
addMe("abc 123 def") returns -1

Your Canvas submission is due at or before 11:59pm on Sunday, November 4, 2018.

All that is required for submission is the URL to your GitHub repository for this problem set.