Java Program to Reverse a String

Given a String, let's say "str", write a Java program to reverse it. In reverse string operation, we need to display the individual characters of string backwards or from right to left. Here, String is a datatype that contains one or more characters and is enclosed in double quotes(" ").

Let's understand the problem with an example ?

Example Scenario: ?

Input: str = "Java Program";
Output: reversed_string = margorP avaJ 

For better understanding refer to the below illustration ?

Using Iteration

In this approach, we use the for loop to iterate through each character of the specified string from the beginning to the end. During each iteration, this loop will take the current character and add it to the a new string which will give the final reversed string.

Example

Here is a Java program that shows how to reverse a string using iteration.

public class ReverseString {
   public static void main (String[] args) {
      String input_string= "Java Program", reverse_string="";
      char temp;
      System.out.println("The string is defined as: " + input_string);
      for (int i=0; i<input_string.length(); i++) {
         temp= input_string.charAt(i);
         reverse_string = temp+reverse_string;
      }
      System.out.println("The reversed string is: "+ reverse_string);
   }
}

Output of the above code is ?

The string is defined as: Java Program
The reversed string is: margorP avaJ

Using StringBuilder Class

StringBuilder is a class in Java that represents a mutable sequence of characters. It provides a method called reverse(), which we will use to reverse the characters of given String.

Example

Let's see how to reverse a String using StringBuilder class.

public class ReverseString {
   public static void main(String[] args) {
      String input_string= "Tutorialspoint", reverse_string="";
      System.out.println("The string is defined as: " + input_string);
      StringBuilder strBuildObj = new StringBuilder(input_string);
      // reverse operation
      reverse_string = strBuildObj.reverse().toString();
      System.out.println("The reversed string is: "+ reverse_string);
   }
}

On running the above code, you will get the following result ?

The string is defined as: Tutorialspoint
The reversed string is: tniopslairotuT