Java Program To Reverse a String

There are many ways to reverse a string in Java. A string can be reversed using StringBuffer, StringBuilder, recursion and using user defined function. So, today we will discuss various methods to reverse value of String variable in Java. Before starting I recommend you to also check how to reverse a number In Java.

Reverse String Using StringBuffer

public class strRev {
    public static void main(String args[]) {

        String strVar = "Code Nirvana Technology Blog";
        
        /* String Reverse Using StringBuffer */
        String revStr = new StringBuffer( strVar ).reverse().toString();
        
        System.out.println( "Before: " + strVar );
        System.out.println( "After: " + revStr );

    }
}

Reverse String Using StringBuilder

public class strRev {
    public static void main(String args[]) {

        String strVar = "Code Nirvana Technology Blog";
        
        /* String Reverse Using StringBuilder */
        String revStr = new StringBuilder( strVar ).reverse().toString();
        
        System.out.println( "Before: " + strVar );
        System.out.println( "After: " + revStr );

    }
}

Reverse String Using User Defined Function

public class strRev {
    public static void main(String args[]) {

        String strVar = "Code Nirvana Technology Blog";
        
        /* String Reverse Using User Defined Function */
        String revStr = revString( strVar );
        
        System.out.println( "Before: " + strVar );
        System.out.println( "After: " + revStr );

    }
    
    public static String revString(String str){
        String rev = "";
        for( int i = str.length()-1; i>=0; i-- ){
            rev = rev + str.charAt(i);
        }
        return rev;
    }
}

Reverse String Using Recursion

public class strRev {
    public static void main(String args[]) {

        String strVar = "Code Nirvana Technology Blog";
        
        /* String Reverse Using Recursion */
        String revStr = revString( strVar );
        
        System.out.println( "Before: " + strVar );
        System.out.println( "After: " + revStr );

    }
    
    public static String revString(String str) {
        if (str.length()<2) {
            return str; 
        }
        return revString(str.substring(1)) + str.charAt(0);
    }
}

More About Recursion: Programs Using Recursion

Output

All In One Java Program To Reverse a String

//Java Program To Reverse a String
//Author: http://www.codenirvana.in/

public class StringReverse {

    public static void main(String args[]) {
        
        String input = "Java Programming is Awesome";
        System.out.println( "Input: " + input + "\n" );
        
        /* String Reverse Using StringBuffer */
        String rev1 = new StringBuffer( input ).reverse().toString();
        
        /* String Reverse Using StringBuilder */
        String rev2 = new StringBuilder( input ).reverse().toString();
        
        /* String Reverse Using User Defined Function */
        String rev3 = revString( input );
        
        /* String Reverse Using Recursion */
        String rev4 = revString( input );
        
        //Print rev variables
        System.out.println( "StringBuffer: " + rev1 );
        System.out.println( "StringBuilder: " + rev2 );
        System.out.println( "Function: " + rev3 );
        System.out.println( "Recursion: " + rev4 );
        
    }
    //String Reverse Function
    public static String revString(String str){
        String rev = "";
        for( int i = str.length()-1; i>=0; i-- ){
            rev = rev + str.charAt(i);
        }
        return rev;
    }
    //String Reverse Recursion Function
    public static String revStrRecursion(String str) {
        if (str.length()<2) {
            return str; 
        }
        return revString(str.substring(1)) + str.charAt(0);
    }
}

Conclusion
Now you know four methods to reverse a string in Java and its one of the famous interview question on Java Programming i.e, What are the various ways you can apply to reverse a sting in Java...

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