Reversing A String Programmatically

Program 1 : Program to Reverse a String (Method – 1 Using for loop)

public class StringReverseProg1 {

//  Java Program to Reverse a String Using for loop
	
	public static void main(String[] args) {
	      
        String str = "Ksamyatam"; 
        String reverseStr = "";
        char ch;

        System.out.println("Original String : " + str);

        for (int i = 0; i < str.length(); i++) {
            ch = str.charAt(i);
            reverseStr = ch + reverseStr; 
        }
      
        System.out.println("Reverse String : " + reverseStr);
    }
}

Output :

Original String : Ksamyatam
Reverse String : mataymasK

Program 2 : Program to Reverse a String (Method – 2 Using String.getBytes() Method)

public class StringReverseProg2 {

//	Java Program to Reverse a String (Method - 2 Using String.getBytes() Method) 	
	
	public static void main(String[] args) {
	      
        String str = "Ksamyatam";
        byte[] arr = str.getBytes();
        byte[] resByte = new byte[arr.length];
		
	System.out.println("Original String : " + str);

        for (int i = 0; i < arr.length; i++)
            resByte[i] = arr[arr.length - i - 1];
		
	String reverseStr = new String(resByte);
        System.out.println("Reverse String : " + reverseStr);

    }
}

Output :

Original String : Ksamyatam
Reverse String : mataymasK

Program 3 : Program to Reverse a String (Method – 3 Using StringBuilder.reverse() Method)

public class StringReverseProg3 {

//	Java Program to Reverse a String Using StringBuilder.reverse() Method
	
	public static void main(String[] args) {
	      
        String str = "Ksamyatam";
        StringBuilder reverseStr = new StringBuilder();

        reverseStr.append(str);
        reverseStr.reverse();

        System.out.println("Original String : " + str);
        System.out.println("Reverse String : " + reverseStr);
    }
}

Output :

Original String : Ksamyatam
Reverse String : mataymasK

Program 4 : Program to Reverse a String (Method – 4 Using Character Array)

public class StringReverseProg4 {

//	Java Program to Reverse a String Using Character Array

	public static void main(String[] args) {
	      
                String str = "Ksamyatam";
                char[] arr = str.toCharArray();
        
		System.out.println("Original String : " + str);		
		System.out.println("\nReverse String Method 1 : ");
		for (int i = arr.length - 1; i >= 0; i--)
	            System.out.print(arr[i]);

	        System.out.println("\n\nReverse String Method 2 : ");
 
                char[] rev = new char[str.length()];
		int j = 0;
		for (int i = arr.length - 1; i >= 0; i--) { 
		    rev[j] = arr[i];
		    j++;
		}
			   	    
	        for (char val : rev) 
                    System.out.print(val);  
    }
}

Output :

Original String : Ksamyatam

Reverse String Method 1 : 
mataymasK

Reverse String Method 2 : 
mataymasK

Program 5 : Program to Reverse a String (Method – 5 Using Collections.reverse() Method)

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.ListIterator;

public class StringReverseProg5 {

//	Java Program to Reverse a String Using Collections.reverse() Method
	
	public static void main(String[] args) {
	      
            String str = "Ksamyatam";
            char[] arr = str.toCharArray();
		
            List<Character> l = new ArrayList<>();

            for (char c : arr)
                l.add(c);

            Collections.reverse(l);      
            ListIterator it = l.listIterator();
      
	    System.out.println("Original String : " + str);
            System.out.println("\nReverse String : ");	
            while (it.hasNext())
               System.out.print(it.next());
    }
}

Output :

Original String : Ksamyatam

Reverse String : 
mataymasK

Program 6 : Program to Reverse a String (Method – 6 Using StringBuffer.reverse() Method)

public class StringReverseProg6 {

//	Java Program to Reverse a String Using StringBuffer.reverse() Method
	
	  public static void main(String[] args){
	      
	        String str = "Ksamyatam";
	        StringBuffer strBuffer = new StringBuffer(str);
	        
	        strBuffer.reverse();
	          
	        System.out.println("Original String : " + str);
		System.out.println("Reverse String : " + strBuffer);    
	  }
}

Output :

Original String : Ksamyatam
Reverse String : mataymasK