Reverse a String in Java

Learn to write Java program to reverse a String. We will first see how to reverse the string, and then we will also see how to reverse the words in the String.

It’s a common puzzle asked in Java interviews at the beginner level. Let’s memorize these solutions for quick recall.

1. Java Program to Reverse the Characters of a String

We can reverse a string by character easily, using a StringBuilder.reverse() method.

String blogName = "HowToDoInJava.com";
 
String reverse = new StringBuilder(string).reverse();
 
System.out.println("Original String -> " + blogName);
System.out.println("Reverse String -> " + reverse);

The program output:

Original String -> HowToDoInJava.com
Reverse String -> moc.avaJnIoDoTwoH

2. Java Program to Reverse the Words of a String

While reversing string content by words, the most natural way is to use a StringTokenizer and a Stack. As you are aware that Stack is a class that implements an easy-to-use last-in, first-out (LIFO) stack of objects.

String description = "Java technology blog for smart java concepts and coding practices";
 
// reverse string builder
StringBuilder reverseString = new StringBuilder();
 
// Put words from String in Stack
Stack<String> myStack = new Stack<>();
 
StringTokenizer tokenizer = new StringTokenizer(description, " ");
 
while (tokenizer.hasMoreTokens()) {
  myStack.push(tokenizer.nextToken());
}
 
//Pop each word from stack and append in builder
 
while (!myStack.empty()) {
  reverseString.append(myStack.pop() + " ");
}
 
System.out.println(reverseString.toString());

The program output:

practices coding and concepts java smart for blog technology Java 

Happy Learning !!

Source Code on Github