java多线程|创建线程的各种方式

/**
 * @Author https://www.javastudy.cloud
 * @CreateTime 2019/11/01
 **/
public class ThreadStudy extends Thread{

    /**
     * 继承Thread类并且重写run方法,
     * 这个方法并不常用,因为一个java类只能继承一个类
     */
    @Override
    public void run() {
        System.out.println("run in sub Thread , Thread name is "+ Thread.currentThread().getName());
    }

    public static void main(String[] args) {
        System.out.println("run in main Thead , Thread name is "+ Thread.currentThread().getName());

        ThreadStudy study = new ThreadStudy();
        //注意启动线程要用 start()方法
        study.start();
        try {
            //让主线程休眠两秒,让子线程有足够的时间运行
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

/**
 * @Author https://www.javastudy.cloud
 * @CreateTime 2019/11/01
 **/
public class ThreadStudy implements Runnable{

    /**
     * 实现Runnable接口,
     * 这个是常用的方法,因为一个java类可以实现多个接口
     */
    @Override
    public void run() {
        System.out.println("run in sub Thread , Thread name is "+ Thread.currentThread().getName());
    }

    public static void main(String[] args) {
        System.out.println("run in main Thead , Thread name is "+ Thread.currentThread().getName());

        //要先new 一个Thread
        // 然后把实现Runnable接口的类传入到Thread的构造函数中
        ThreadStudy study = new ThreadStudy();
        Thread thread = new Thread(study);

        //注意启动线程要用 start()方法
        thread.start();
        try {
            //让主线程休眠两秒,让子线程有足够的时间运行
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

/**
 * @Author https://www.javastudy.cloud
 * @CreateTime 2019/11/01
 **/
public class ThreadStudy {


    public static void main(String[] args) {
        System.out.println("run in main Thread , Thread name is "+ Thread.currentThread().getName());

        // 不用类实现Runnable接口了, 直接这样定义,方便,省事
        Runnable runnable = ()-> System.out.println("run in sub Thread, Thread name is "+Thread.currentThread().getName());
        // 启动这个线程还是要用Thread来包装下,然后调用Thread.start()方法
        Thread thread = new Thread(runnable);
        thread.start();
        try {
            //让主线程休眠两秒,让子线程有足够的时间运行
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

/**
 * @Author https://www.javastudy.cloud
 * @CreateTime 2019/11/01
 **/
public class ThreadStudy {


    public static void main(String[] args) {
        System.out.println("Run in main Thread, Thread name is "+ Thread.currentThread().getName());

        //一句话就可以创建一个线程池下面这种写法线程没有上限,实际开发中不太推荐
        // 开发中一般是用下行注释的方法,或者自定义线程池参数
        // 常用的还有 Executors.newFixedThreadPool(10);去创建固定10个线程的池子,这个也有弊端,就是等待的队列没有上界
        //
        ExecutorService service = Executors.newCachedThreadPool();
        // 没有返回值的处理
        service.submit(()-> System.out.println("Run in sub Thread, Thread name is "+Thread.currentThread().getName()));
        // 有返回值的处理,用一个Future 去接收
        Future<String> submit = service.submit(() -> "Run in sub Thread with return , Thread name is " + Thread.currentThread().getName());

        //输出future里面的值
        try {
            System.out.println(submit.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }

    }
}