reverse of string in java with or without StringBuffer

How to reverse String in Java with or without StringBuffer Example

Reverse String in Java

There are many ways to reverse String in Java. You can use rich Java API to quickly reverse contents of any String object. Java library provides StringBuffer and StringBuilder class with reverse() method which can be used to reverse String in Java. Since converting between String and StringBuffer or StringBuilder is very easy it's the most easy way available to reverse String in Java. At the same time Writing Java program to reverse String in Java without StringBuffer is one of the popular Java String interview question, which requires you to reverse String by applying logic and by not using API methods. Since reverse is a recursive job, you can use recursion as well as loop to reverse String in Java. In this Java tutorial I have shown How to reverse String using StringBuffer, StringBuilder and using pure loop with logic. You can also checkHow to reverse String with recursion in Java, if you want to see recursive code. let's see complete Java program for this beautiful Java programming exercise.

program::

/**
 *
 * Java program to reverse String in Java. There are multiple ways to reverse
 * String in Java, you can either take help of standard Java API StringBuffer
 * to reverse String in Java. StringBuffer has a reverse() method which return StringBuffer
 * with reversed contents. On the other hand you can also reverse it by applying your
 * own logic, if asked to reverse String without using StringBuffer in Java. By the way
 * you can also use StringBuilder to reverse String in Java. StringBuilder is non thread-safe
 * version of StringBuffer and provides similar API. You can use StringBuilder's reverse()
 * method to reverse content and then convert it back to String
 *
 * @author http://java67.blogspot.com
 */
public class StringReverseExample {


    public static void main(String args[]) {
   
        //quick wasy to reverse String in Java - Use StringBuffer
        String word = "HelloWorld";
        String reverse = new StringBuffer(word).reverse().toString();
        System.out.printf(" original String : %s , reversed String %s  %n", word, reverse);
   
        //another quick to reverse String in Java - use StringBuilder
        word = "WakeUp";
        reverse = new StringBuilder(word).reverse().toString();
        System.out.printf(" original String : %s , reversed String %s %n", word, reverse);
   
        //one way to reverse String without using StringBuffer or StringBuilder is writing

        //own utility method
        word = "Band";
        reverse = reverse(word);
        System.out.printf(" original String : %s , reversed String %s %n", word, reverse);
    } 


    public static String reverse(String source){
        if(source == null || source.isEmpty()){
            return source;
        }    
        String reverse = "";
        for(int i = source.length() -1; i>=0; i--){
            reverse = reverse + source.charAt(i);
        }
   
        return reverse;
    }
 
}

Output:
original String : HelloWorld , reversed String dlroWolleH
original String : WakeUp , reversed String pUekaW
original String : Band , reversed String dnaB