java replace first occurrence of substring

/**
 * @author lautturi.com 
 * Java example: replace first substring of string in java
 */

import java.util.*;

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

		String str = "welcome, hello lautturi, hello java";
		
		str = str.replaceFirst("hello", "hi"); 
				
		System.out.println(str);
	}
}

output:

welcome, hi lautturi, hello java