Java Program to Reverse a String

June 30, 2023

Program to reverse the string

In this article we will learn how to reverse a string in Java

Reversing a string is a technique so that the 1st character becomes the last character and so on.

Suppose we have a string called “prepinsta” so we have to find reverse of that string is “atsniperp” we can do this in two way by using reverse method of StringBuilder class and by using normal for loop with charAt() method.

reverse a string

Algorithm

  • Take a string input from the user
  • Store it in the variable called “s” in this case
  • After that we will append that string variable in the StringBuilder
  • After that reverse the StringBuilder object by using  the reverse function.
program to reverse a string

Code in Java (Program to reverse the string)

Run 
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
    String s ="Prepinsta";
    StringBuilder sb = new StringBuilder();
    sb.append(s);
    System.out.println( "String is : "+sb);
    sb.reverse();
   System.out.println("Reversed string is : "+sb);
  }
}
String is : Prepinsta
Reversed string is : atsniperP

(Method-2)

  • Take a string input from the user
  • Store it in the variable called “s” in this case
  • Take a String “rev” variable and initialize with empty string
  • Start i for loop start from i=s.length()-1 to i>=0
  • Get one by one character with the help of charAt() and store it in the “rev” variable 
  • At last print that “rev” variable

Code In Java

Run 
import java.util.Scanner;
public class Main {
  public static void main(String[] args) {
    String s = "prepinsta";
    String rev = "";

    for (int i = s.length()-1; i >=0; i--) {
      rev=rev+s.charAt(i);
    }
    System.out.println(rev);
  }
}

Output

String is : prepinsta
Reversed string is : atsniperp
 
 

Toggle each character in a string

Count the number of vowels

Length of the string without using strlen() function

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3 comments on “Java Program to Reverse a String”


  • Khushi Saxena

    import java.util.*;
    class HelloWorld {
    public static void main(String[] args) {
    Scanner sc=new Scanner(System.in);
    String s=sc.nextLine();
    String rev=””;
    for(int i=s.length()-1;i>=0;i–){
    char c=s.charAt(i);
    rev+=c;
    }
    System.out.print(rev);

    }
    }


  • Fadal Razin

    We can also reverse a string using StringBuffer :
    public class StringBufferReverseExample {
    public static void main(String[] args) {
    String input = “Hello world”;
    StringBuffer sb = new StringBuffer(input);
    sb.reverse();
    String reversed = sb.toString();
    System.out.println(reversed);
    }
    }


  • Chinmai

    import java.util.*;
    public class Main
    {
    public static void main(String[] args) {
    String name = “chinmai”;
    String res = “”;
    Stack s = new Stack();
    for(char c : name.toCharArray()){
    s.add(c);
    }
    while(!s.isEmpty()){
    res+=s.pop();
    }
    System.out.println(res);
    }
    }