创建线程的几种方式

1.Thread类

继承Thread类，重写run()方法

public class ThreadDemo {
    public static void main(String[] args) {
        MyThread thread = new MyThread();
        thread.start();
    }
}

class MyThread extends Thread{
    @Override
    public void run() {
        System.out.println("MyThread");
    }
}

注意：调用了start方法以后，线程才算启动，虚拟机会先为我们创建一个线程，等到这个线程第一次得到时间片时再调用run()方法，不可多次调用start()方法，否则会抛出异常java.lang.IllegalThreadStateException

2.实现Runnable接口

public class ThreadDemo2 {
    public static void main(String[] args) {
        Thread thread = new Thread(new MyThread2());
        thread.start();
        new Thread(()->{
            System.out.println("Java8匿名内部类");
        },"aaa").start();
    }


}

class MyThread2 implements Runnable{
    @Override
    public void run() {
        System.out.println("MyThread");
    }
}

3.实现Callable接口

public class Task implements Callable {
    @Override
    public Integer call() throws Exception {
        Thread.sleep(1000);
        return 10;
    }

    public static void main(String[] args) throws Exception {
        ExecutorService executorService = Executors.newCachedThreadPool();
        Task task = new Task();
        Future result = executorService.submit(task);
        System.out.println(result.get(1, TimeUnit.SECONDS));
    }
}