In this project I am creating and testing methods checking if a given String is a palindrom.
A palindrome is a word, phrase, number, or other sequences of characters which reads the same backward as forward, such as “madam” or “racecar”.
In the project I have tested created methods using Junit unit-testing framework. In order to implement it first I added junit-jupiter dependency to my pom.xml file.
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<version>5.9.0</version>
</dependency>In the Palindrome class I created 3 different methods checking if a particular input is or contains one or many palindromes
In the first method I used a for loop:
public static boolean isPalindromeFor(String input) {
if (input.isEmpty()) {
return false;
}
String editedInput = input.replaceAll("\\s+", "").toLowerCase();
for (int i = 0; i < editedInput.length() / 2; i++) {
if (editedInput.charAt(i) != editedInput.charAt(editedInput.length() - i - 1)) {
return false;
}
}
return true;
}In the second method I used a while loop:
public static boolean isPalindromeWhile(String input) {
if (input.isEmpty()) {
return false;
}
String editedInput = input.replaceAll("\\s+", "").toLowerCase();
int left = 0;
int right = editedInput.length() - 1;
while (left < right) {
if (editedInput.charAt(left) != editedInput.charAt(right))
return false;
left++;
right--;
}
return true;
}The last method takes as an input an Array of Strings and return a List of palindromes present in that array:
public static List<String> isPalindromeArray(String[] input) {
if (input.length == 0) {
return Collections.emptyList();
}
List<String> result = new ArrayList<>();
for (String s : input) {
s.replaceAll("\\s+", "").toLowerCase();
if (isPalindromeFor(s)) {
result.add(s);
}
}
return result;
}Notice that in all of the above methods first I am checking if the input String is empty or String array length is zero accordingly:
if (input.isEmpty()) {
return false;
}if (input.length == 0) {
return Collections.emptyList();
}Also before checking that the particular input is a palindrome or contains a palindrome I process the input to ignore case sensitivity using .toLowerCase() method. Also in order to remove spaces between words in the strings I use a replceAll() method which is accepting a regex pattern for a sequence that needs to replced and an empty String tas a replacement:
String editedInput = input.replaceAll("\\s+", "").toLowerCase();For each othe methods I created a test checking if the method given an input that is a pilindrome will return true or if an input is an array of palindromes the method will return a list of all palindromes in an array
I also use parameterized tests using @ParameterizedTest and @CsvSource() annotations allowing me to test mny different inputs in one testing method:
@ParameterizedTest
@CsvSource({"A", "a", "civic", "Level", "RaDaR","Taco cat", "Aibohphobia",
"Was it a car or a cat I saw", "Too bad I hid a boot", "Mr Owl ate my metal worm"})
@DisplayName("Given a palindrome input should return true")
public void isPalindromeWhileTest_shouldReturnTrue(String input) {
boolean result = Palindrome.isPalindromeWhile(input);
assertTrue(result);
}
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