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 ith position in original string will have a position of (string length -i)th position in the new reversed string.
In this tutorial, we will go through some example Java programs that demonstrate the procedure to reverse a string.
Example 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
/** * Java Example Program, to reverse a String in 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
Example 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
/** * Java Example Program, to reverse a String in 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
Example 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
/** * Java Example Program, to reverse a String in 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.