Reverse String Without Using Split in Java

To reverse a string without using the split function, we can perform the action in the following ways:

By Using toCharArray() Method

The length keyword is  used in the program, and it returns the overall length of the string variable.

The for loop continues until the string index zero ends.

ReverseString.java

import java.io.*;
import java.util.*;
import java.io.*;
public class ReverseString
{
//ReverseString using CharcterArray.
public static void main(String[] args) {
// creating object for the scanner class to take inputs during the run time
Scanner sc=new Scanner(System.in);
System.out.println("Enter the string");
// declaring and initialising  variable


String s=sc.nextLine();


System.out.println("The given string is ");
System.out.println(s);
        // convert the given string to character array by using toCharArray
        char[] result = s.toCharArray();
        //iterating through the char array and printing it 
        for (int j = result.length - 1; j >= 0; j--)
	{
         // printing the reversed String
            System.out.print(result[j]);
	}
}
}

Output:

Enter the string
Hellow World
The given string is 
Hellow World
dlroW wolleH

Method 2

• The goal is to go through the string's entire length.
• While navigating, extract each character.
•  Add each character to the string's front.

RevsersString2.java

import java.util.*;
import java.io.*;
public class RevsersString2
{
public static void main(String[] args) {
// declaring variable
Scanner sc=new Scanner(System.in);
System.out.println("Enter the string");
String s=sc.nextLine();
System.out.println("The given string is ");
System.out.println(s);
String result="";
        //iterating through the char array and printing it 
        for (int i=0; i<s.length(); i++)
      {
        char ch= s.charAt(i); // extracting each character from the string 
        result= ch+result; // add each character to the string
      }
      System.out.println("The revered string is");
      System.out.println(result);
}
}

Output:

Enter the string
Java Programming
The given string is 
Java Programming
The revered string is
gnimmargorP avaJ

Using Byte Array

• Establish a temporary byte[] with a length equal to the input string.
• Put the bytes (which we obtained using the getBytes() method) into the temporary byte[] in reverse order.
• Make a new String subject using the result's byte[] storage.

ReverseString3.java

import java.util.*;
import java.io.*;
public class ReverseString3
{
public static void main(String[] args) {
// declaring variable
Scanner sc=new Scanner(System.in);
System.out.println("Enter the string");
String s=sc.nextLine();
System.out.println("The given string is ");
System.out.println(s);
        byte[] byteArray = s.getBytes();
        byte[] result = new byte[byteArray.length];
        // Store result in reverse order into the result byte[]
        for (int j = 0; j < byteArray.length; j++)
            result[j] = byteArray[byteArray.length - j - 1];
        System.out.println("The reversed string is");
        System.out.println(new String(result));
}
}

Output:

Enter the string
Heloo Everyone
The given string is 
Hello Everyone
The reversed string is
enoyrevE olleH

Using StringBuilder Class

Since the String class lacks a reverse() method, we must transform the input string to a StringBuilder instead. This is done by utilizing the StringBuilder's append method. Print the characters of the inverted string after that by scanning through the first through the final index.

ReverseString4.java

import java.util.*;
import java.io.*;
public class ReverseString4
{
public static void main(String[] args) {
// declaring variable
Scanner sc=new Scanner(System.in);
System.out.println("Enter the string");
String s=sc.nextLine();
System.out.println("The given string is ");
System.out.println(s);
StringBuilder s1 = new StringBuilder();
    s1.append(s);
    s1.reverse();
    // printing the  reversed String
    System.out.println(s1);
}
}

Output:

Enter the string
Java String
The given string is 
Java String
gnirtS avaJ

Using While Loop

In this approach, we first create an empty string to hold the reversed string. We then initialize an integer i to the last index of the input string, which is obtained using the length() method. We then enter a while loop that continues as long as i is greater than or equal to 0. Inside the loop, we add the character at the current index i to the reversed string using the charAt() method, and then decrement i. Once the loop has completed, we return the reversed string.

ReverseString5.java

import java.util.*;
import java.io.*;
public class ReverseString5
{
// Main section of the program from where execution begins
public static void main(String[] args) {
// declaring variable
Scanner sc=new Scanner(System.in);
System.out.println("Enter the string");
String s=sc.nextLine();
System.out.println("The given string is ");
System.out.println(s);
int l= s.length();
System.out.println("The reversed string ");
while( l>0)
{
System.out.print(s.charAt(l -1)); 
l--;
}
}
}

Output:

Enter the string
This is String reverse program
The given string is 
This is String reverse program
The reversed string 
margorp esrever gnirtS si sihT

Using For Loop

In this approach, we use a for loop to iterate over the indices of the input string in reverse order. We initialize the loop counter i to the last index of the input string, and then continue as long as i is greater than or equal to 0. Inside the loop, we add the character at the current index i to the reversed string using the charAt() method. Finally, once the loop has completed, we return the reversed string.

RevereString.java

Enter the string
This is String reverse program
The given string is 
This is String reverse program
The reversed string 
margorp esrever gnirtS si sihT

Output

Enter the string
Hello world
The given string is 
Hello world
The reversed string 
dlrow olleH