How do I swap the case of words in a String?
Author: Deron Eriksson
Description: This Java example shows how to swap the case of words in a String.
Tutorial created using: Windows XP || JDK 1.5.0_09 || Eclipse Web Tools Platform 2.0 (Eclipse 3.3.0)

Swapping uppercase and lowercase characters in a String can be accomplished using the swapCase() method on the WordUtils utility class in the Commons LangS library. The SwapCaseTest class demonstrates this.

package test;


import org.apache.commons.lang.WordUtils;

public class SwapCaseTest {

	public static void main(String[] args) throws IOException {
		swapCase("this is a string");
		swapCase("This is another string.");
		swapCase("HERE IS ANOTHER");
		swapCase("oNE lAST sTRING");

	public static void swapCase(String string) {
		System.out.println(string + " | original");
		System.out.println(WordUtils.swapCase(string) + " | WordUtils.swapCase(string)");


The console output of SwapCaseTest is shown below.


this is a string | original
THIS IS A STRING | WordUtils.swapCase(string)

This is another string. | original
tHIS IS ANOTHER STRING. | WordUtils.swapCase(string)

HERE IS ANOTHER | original
here is another | WordUtils.swapCase(string)

oNE lAST sTRING | original
One Last String | WordUtils.swapCase(string)