How to Reverse a String in Java





In this blog, we will learn how to reverse a string in Java. This will be asked in the most of the interviews. This can be implemented in four different ways listed below:

  1. Convert String into Character Array and use For loop
  2. For loop with CharAt() method
  3. Using StringBuffer class
  4. Using StringBuilder class


Method 1:

Convert String into Character Array and use For loop

In the below snippet, we have done the following:

  • Creating a new string and assigning a custom string value to it
  • Converting this string to character array using toCharArray() method
  • Calculating the length of character array and assigning it to a int variable.
  • Using for loop, we will iterate this to print the string in reverse

public class StringReverseDemo {

	public static void main(String[] args) {

		String inputstring = "Krishna";
		char[] chars = inputstring.toCharArray();
		int length = chars.length;
		
		for (int i = length-1; i >=0; i--) {
			System.out.print(chars[i]);
			
		}

	}

}

Method 2:

Convert String into Character Array and use For loop

In the below snippet, we have done the following:

  • Creating a new string and assigning a custom string value to it
  • Converting this string to character array using toCharArray() method
  • Calculating the length of character array and assigning it to a int variable.
  • Creating an another new string to concat the values to a brand new string
  • Using charAt() method, we will iterate this for loop to print the string in reverse and concat it to the newly created string
public class StringReverseDemo {

	public static void main(String[] args) {
		
		String inputstring = "Krishna";
		String revword = "";
		char[] chars = inputstring.toCharArray();
		int length = chars.length;
		
		for (int i = length-1; i >=0; i--) {
			revword = revword+inputstring.charAt(i);
		}
		System.out.println(revword);

	}

}




Method 3:

Using StringBuffer class

We can use StringBuffer class to reverse a string value with help of its inbuilt methods directly as below:


public class StringReverseDemo {

	public static void main(String[] args) {
		
		String inputstring = "Krishna";

		StringBuffer stringbuffer = new StringBuffer(inputstring);
		System.out.println(stringbuffer.reverse());
		
	}

}

Method 4:

Using StringBuilder class

We can use StringBuilder class to reverse a string value with help of its inbuilt methods directly as below:


public class StringReverseDemo {

	public static void main(String[] args) {
		
		String inputstring = "Krishna";

		StringBuilder stringbuilder = new StringBuilder(inputstring);
		System.out.println(stringbuilder.reverse());
		
	}

}



Please watch the Youtube video for better understanding.



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