Refactored ReverseStringUsingStack utility for reversing strings using stack

Author: navaneedan07

src/main/java/com/thealgorithms/stacks/ReverseStringUsingStack.java

@@ -0,0 +1,34 @@
+package com.thealgorithms.stacks;
+
+import java.util.Stack;
+
+public final class ReverseStringUsingStack {
+    private ReverseStringUsingStack() {
+    }
+
+    /**
+     * @param str string to be reversed using stack
+     * @return reversed string
+     */
+    public static String reverse(String str) {
+        // Check if the input string is null
+        if (str == null) {
+            throw new IllegalArgumentException("Input string cannot be null");
+        }
+        Stack<Character> stack = new Stack<>();
+        StringBuilder reversedString = new StringBuilder();
+        // Check if the input string is empty
+        if (str.isEmpty()) {
+            return str;
+        }
+        // Push each character of the string onto the stack
+        for (char ch : str.toCharArray()) {
+            stack.push(ch);
+        }
+        // Pop each character from the stack and append to the StringBuilder
+        while (!stack.isEmpty()) {
+            reversedString.append(stack.pop());
+        }
+        return reversedString.toString();
+    }
+}

src/main/java/com/thealgorithms/strings/ReverseString.java

@@ -1,5 +1,7 @@
 package com.thealgorithms.strings;
 
+import java.util.Stack;
+
 /**
  * Reverse String using different version
  */
@@ -57,4 +59,31 @@ public static String reverse3(String string) {
         }
         return sb.toString();
     }
+
+    /**
+     * Reverse version 4 the given string using a Stack.
+     * This method pushes each character of the string onto a stack
+     * and then pops them off to create the reversed string.
+     */
+    public static String reverse4(String str) {
+        // Check if the input string is null
+        if (str == null) {
+            throw new IllegalArgumentException("Input string cannot be null");
+        }
+        Stack<Character> stack = new Stack<>();
+        StringBuilder reversedString = new StringBuilder();
+        // Check if the input string is empty
+        if (str.isEmpty()) {
+            return str;
+        }
+        // Push each character of the string onto the stack
+        for (char ch : str.toCharArray()) {
+            stack.push(ch);
+        }
+        // Pop each character from the stack and append to the StringBuilder
+        while (!stack.isEmpty()) {
+            reversedString.append(stack.pop());
+        }
+        return reversedString.toString();
+    }
 }