how to remove letters from string in java

/**
 * @author lautturi.com
 * Java example: remove chars from string in java
 */

import java.util.*;

public class Lautturi {

	public static void main(String[] args) {

		String str = "hello lautturi java world!";
		
		// remove all l letters
		String str1 = str.replace("l", "");
		System.out.println(str1);
		
		// remove the last letter
		String str2 = str.substring(0,str.length()-1);
		System.out.println(str2);
		
		// remove the letter from string at the position idx 
		int idx = 5;
		String str3 = "";
		if(idx>0 && idx<str.length()) {
			str3 = str.substring(0,idx-1)+str.substring(idx,str.length()-1);
		}
		else {
			str3 = str;
		}
		System.out.println(str3);
		
	}
}

output:

heo autturi java word!
hello lautturi java world
hell lautturi java world