Java – Reverse a String

In this Java tutorial, you will learn how to reverse a string in different ways like iterating over the characters and arranging them in reverse order, or using StringBuilder.reverse() method, with examples.

Reverse a String in Java

There are many ways in which you can reverse a String in Java.

Reversing a string means, character at the i^th position in original string will have a position of (string length -i)^th position in the new reversed string.

Examples

1. Reverse string using String.getBytes

In this example program, we shall get the bytes of given string using String.getBytes() function. Then using a For loop, read each character one by one and arrange them in reverse order.

ReverseString.java

public class ReverseString {
	public static void main(String[] args) {
		String str = "www.tutorialkart.com";
		String reverseStr="";
		
		for(byte c:str.getBytes()){
			reverseStr=(char)c+reverseStr;
		}
		System.out.println("Original String is : "+str);
		System.out.println("Reversed String is : "+reverseStr);
	}
}

When the above program is run, output to the console window shall be as shown below.

Output

Original String is : www.tutorialkart.com
Reversed String is : moc.traklairotut.www

2. Reverse string using String.charAt()

In this example, we shall traverse through the string from first character to last character using for loop, incrementing index and String.charAt() function.

ReverseString.java

public class ReverseString {
	public static void main(String[] args) {
		String str = "www.tutorialkart.com";
		String reverseStr="";
		
		for(int i=0;i<str.length();i++) {
			reverseStr = str.charAt(i) + reverseStr;
		}
		
		System.out.println("Original String is : "+str);
		System.out.println("Reversed String is : "+reverseStr);
	}
}

Run the above program and you should get the output printed to the console as shown below.

Output

Original String is : www.tutorialkart.com
Reversed String is : moc.traklairotut.www

3. Reverse string using StringBuilder

StringBuilder is a very useful class when you doing string operations like concatenation, reverse, etc., on large strings.

In this example, we shall create a StringBuilder with the given string and use its function StringBuilder.reverse() to reverse the original string.

ReverseString.java

public class ReverseString {
	public static void main(String[] args) {
		String str = "www.tutorialkart.com";
		
		StringBuilder sb = new StringBuilder(str);
		sb.reverse();
		
		String reverseStr = sb.toString();
		
		System.out.println("Original String is : "+str);
		System.out.println("Reversed String is : "+reverseStr);
	}
}

Run the program.

Output

Original String is : www.tutorialkart.com
Reversed String is : moc.traklairotut.www

Conclusion

In this Java Tutorial, we have learnt how to reverse a given String in Java.