This article discusses Java programs to:

• Reverse each word in a String in Java
• Reverse order of words in a String in Java

 

Reverse order of words in a String

public static void reverseStringByWord(String originalString) {
    StringBuilder result = new StringBuilder();
    String[] words = originalString.split("\\s+");      
    for (int i = words.length - 1 ; i>=0; i--) {
      result.append(words[i]).append(' ');
    }
    System.out.println("String in reverse order of words: " + result.toString().trim());
  }

 

Reverse each word in a String

private static void reverseEachWord(String originalString){
  String[] words = originalString.split("\\s+");
  String reverseString = "";
  for(int i=0;i<words.length;i++){
    String word = words[i];
    String reverseWord = new StringBuilder(word).reverse().toString();
    reverseString += " " + reverseWord ;
  }
  System.out.println("String with each word reversed: " + reverseString);
}

 
If you don’t want to use the StringBuilder reverse() function, refer this article for the corresponding algorithm :

String reversal algorithm
 

Here is the complete program :

package com.topjavatutorial;

public class StringReversal {

  public static void main(String[] args) {

    String originalString = "Hello World";
    System.out.println("Original String : " + originalString);

    // String with each word reversed
    reverseStringByWord(originalString);

    // String in reverse order of words
    reverseEachWord(originalString);
  }

  private static void reverseEachWord(String originalString) {
    String[] words = originalString.split("\\s+");
    String reverseString = "";
    for (int i = 0; i < words.length; i++) {
      String word = words[i];
      String reverseWord = new StringBuilder(word).reverse().toString();
      reverseString += " " + reverseWord;
    }
    System.out.println("String with each word reversed: " + reverseString);
  }

  public static void reverseStringByWord(String originalString) {
    StringBuilder result = new StringBuilder();
    String[] words = originalString.split("\\s+");
    for (int i = words.length - 1; i >= 0; i--) {
      result.append(words[i]).append(' ');
    }
    System.out.println("String in reverse order of words: "
        + result.toString().trim());
  }

}

Output :

Original String : Hello World
String in reverse order of words: World Hello
String with each word reversed:  olleH dlroW

 

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