W3School TIY Editor

public class Main extends Thread { public static int amount = 0; public static void main(String[] args) { Main thread = new Main(); thread.start(); // 等待线程执行完成 while(thread.isAlive()) { System.out.println("等待中..."); } // 更新 amount 并打印其值 System.out.println("主线程: " + amount); amount++; System.out.println("主线程: " + amount); } public void run() { amount++; } }