package sirop;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author zhaoshuli
 */
public class SIROP {
    public static void main(String[] args){
    System.out.println("hello world");
    }
    
}

package sirop;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author zhaoshuli
 */
public class SIROP {
    public static void main(String[] args){
    System.out.println("Welcome to SIROP!");
    }
    
}

Change main method message