[BAEL-8232] - Moved java string related code and github links into new module java-strings

java-strings/src/main/java/com/baeldung/string/Palindrome.java

@@ -0,0 +1,66 @@
+package com.baeldung.string;
+
+import java.util.stream.IntStream;
+
+public class Palindrome {
+
+    public boolean isPalindrome(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        int length = clean.length();
+        int forward = 0;
+        int backward = length - 1;
+        while (backward > forward) {
+            char forwardChar = clean.charAt(forward++);
+            char backwardChar = clean.charAt(backward--);
+            if (forwardChar != backwardChar)
+                return false;
+        }
+        return true;
+    }
+
+    public boolean isPalindromeReverseTheString(String text) {
+        StringBuilder reverse = new StringBuilder();
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        char[] plain = clean.toCharArray();
+        for (int i = plain.length - 1; i >= 0; i--)
+            reverse.append(plain[i]);
+        return (reverse.toString()).equals(clean);
+    }
+
+    public boolean isPalindromeUsingStringBuilder(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        StringBuilder plain = new StringBuilder(clean);
+        StringBuilder reverse = plain.reverse();
+        return (reverse.toString()).equals(clean);
+    }
+
+    public boolean isPalindromeUsingStringBuffer(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        StringBuffer plain = new StringBuffer(clean);
+        StringBuffer reverse = plain.reverse();
+        return (reverse.toString()).equals(clean);
+    }
+
+    public boolean isPalindromeRecursive(String text) {
+        String clean = text.replaceAll("\\s+", "").toLowerCase();
+        return recursivePalindrome(clean, 0, clean.length() - 1);
+    }
+
+    private boolean recursivePalindrome(String text, int forward, int backward) {
+        if (forward == backward)
+            return true;
+        if ((text.charAt(forward)) != (text.charAt(backward)))
+            return false;
+        if (forward < backward + 1) {
+            return recursivePalindrome(text, forward + 1, backward - 1);
+        }
+
+        return true;
+    }
+
+    public boolean isPalindromeUsingIntStream(String text) {
+        String temp = text.replaceAll("\\s+", "").toLowerCase();
+        return IntStream.range(0, temp.length() / 2)
+            .noneMatch(i -> temp.charAt(i) != temp.charAt(temp.length() - i - 1));
+    }
+}