Replace character in string with specified index

/**
 * @author lautturi.com 
 * Java example: replace a specific character in string
 */

import java.util.*;

public class Lautturi {
	public static void main(String[] args) {

		//Orlautturinal String
		String str = "Hallo java.";
		// character to replace
		char ch = 'e'; 
		// replaced index
		int index = 1;
		// replace string
		StringBuilder sb = new StringBuilder(str); 
        sb.setCharAt(index, ch); 

		System.out.println(sb.toString());
	}
}

output:

Hello java.