Java Programs

Reverse a String

import java.util.*;
 
class ReverseString
{
   public static void main(String args[])
   {
      String original, reverse = "";
      Scanner in = new Scanner(System.in);
 
      System.out.println("Enter a string to reverse");
      original = in.nextLine();
 
      int length = original.length();
 
      for ( int i = length - 1 ; i >= 0 ; i-- )
         reverse = reverse + original.charAt(i);
 
      System.out.println("Reverse of entered string is: "+reverse);
   }
}

class InvertString
{
   public static void main(String args[])
   {
      StringBuffer a = new StringBuffer("Java programming is fun");
      System.out.println(a.reverse());
   }
}



public class StringRecursiveReversal {

 

    String reverse = "";

     

    public String reverseString(String str){

         

        if(str.length() == 1){

            return str;

        } else {

            reverse += str.charAt(str.length()-1)

                    +reverseString(str.substring(0,str.length()-1));

            return reverse;

        }

    }

     



public String reverseString(String s){
    if (s.length() == 0) 
         return s;

    return reverseString(s.substring(1)) + s.charAt(0);
}

Reverse a Number in Java

import java.util.Scanner;
 
class ReverseNumber
{
   public static void main(String args[])
   {
      int n, reverse = 0;
 
      System.out.println("Enter the number to reverse");
      Scanner in = new Scanner(System.in);
      n = in.nextInt();
 
      while( n != 0 )
      {
          reverse = reverse * 10;
          reverse = reverse + n%10;
          n = n/10;
      }
 
      System.out.println("Reverse of entered number is "+reverse);
   }
}