java多线程中执行多个程序的实例分析

import java.awt.Graphics;
import java.util.Random;
public class ThreadClass extends Thread{
public Graphics g;
//用构造器传参的办法将画布传入ThreadClass类中
public ThreadClass(Graphics g){
this.g=g;
}
public void run(){
//获取随机的x,y坐标作为小球的坐标
Random ran=new Random();
int x=ran.nextInt(900);
int y=ran.nextInt(900);
for(int i=0;i<100;i++){
g.fillOval(x+i,y+i,30,30);
try{
Thread.sleep(30);
}catch(Exception ef){
}
}
}
}

public void actionPerformed(ActionEvent e){
ThreadClass thc=new ThreadClass(g);
thc.start();
}

public class Main {
  //method to print numbers from 1 to 10
  public static void printNumbers() {
    for (int i = 1; i <= 10; i++) {
      System.out.print(i + " ");
    }
    //printing new line
    System.out.println();
  }
 
  //main code	
  public static void main(String[] args) {
    //thread object creation
    Thread one = new Thread(Main::printNumbers);
    Thread two = new Thread(Main::printNumbers);
 
    //starting the threads
    one.start();
    two.start();
  }
}