Java Program for Reverse String

In this post, we will see, How to write a program for reverse String in java. 

A java string is an object representing a sequence of characters.  

Let's create a string variable 

Input:- String str = "Java";

Output:- "avaj"

Code Using an Inbuilt method ( reverse() ) of  StringBuilder

import java.util.Scanner;

public class ReverseString {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

System.out.print("Enter a string: ");

String str = sc.nextLine();

StringBuilder sb = new StringBuilder(str);

System.out.println("Reversed string: " + sb.reverse().toString());

}

}

Output:- 

Enter a string: java
Reversed string: avaj

Explanations-

• Created the Object of Scanner class
• Ask the user to Enter a String using Standard input stream
• Created the object of StringBuilder class
• Then used the reverse() method of StringBuilder class 

Another process of Code using for loop 

import java.util.Scanner;

public class ReverseString {

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

System.out.print("Enter a string: ");

String str = sc.nextLine();

char[] ch = str.toCharArray();

        String rev = "";

       for( int i = (ch.length-1); i >= 0; i-- ) {

       rev = rev + ch[i];

       }

       System.out.println("Reverese String : "+rev);

    }

}

Output:-

Enter a string: java
Reverse string: avaj

Explanations-

• Created the Object of Scanner class
• Ask the user to Enter a String using Standard input stream
• Store the input string in str variable
• Then Convert the string to char array 
• the iterate the character from last to first 
• Then store the char value in rev string variable

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