7.剑指JavaOffer-多线程与并发

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区别

run方法还是主子线程执行的

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示例：

public class MyThread extends Thread {
    private String name;
    public MyThread(String name){
        this.name = name;
    }
    @Override
    public void run(){
        for(int i = 0 ; i < 10 ; i ++){
            System.out.println("Thread start : " + this.name + ",i= " + i);
        }
    }
}

public class ThreadDemo {
    public static void main(String[] args) {
        MyThread mt1 = new MyThread("Thread1");
        MyThread mt2 = new MyThread("Thread2");
        MyThread mt3 = new MyThread("Thread3");
        mt1.start();
        mt2.start();
        mt3.start();
    }
}

public class MyRunnable implements Runnable {
    private String name;
    public MyRunnable(String name){
        this.name = name;
    }
    @Override
    public void run(){
        for(int i = 0 ; i < 10 ; i ++){
            System.out.println("Thread start : " + this.name + ",i= " + i);
        }
    }
}

public class RunnableDemo {
    public static void main(String[] args) throws InterruptedException {
        MyRunnable mr1 = new MyRunnable("Runnable1");
        MyRunnable mr2 = new MyRunnable("Runnable2");
        MyRunnable mr3 = new MyRunnable("Runnable3");
        Thread t1 = new Thread(mr1);
        Thread t2 = new Thread(mr2);
        Thread t3 = new Thread(mr3);
        t1.start();
        t2.start();
        t3.start();
    }
}

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FurtureTask示例：

public class MyCallable implements Callable<String> {
    @Override
    public String call() throws Exception{
        String value="test";
        System.out.println("Ready to work");
        Thread.currentThread().sleep(5000);
        System.out.println("task done");
        return  value;
    }

}

public class FutureTaskDemo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        FutureTask<String> task = new FutureTask<String>(new MyCallable());
        new Thread(task).start();
        if(!task.isDone()){
            System.out.println("task has not finished, please wait!");
        }
        System.out.println("task return: " + task.get());

    }
}

public class ThreadPoolDemo {
    public static void main(String[] args) {
        ExecutorService newCachedThreadPool = Executors.newCachedThreadPool();
        Future<String> future = newCachedThreadPool.submit(new MyCallable());
        if(!future.isDone()){
            System.out.println("task has not finished, please wait!");
        }
        try {
            System.out.println(future.get());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        } finally {
            newCachedThreadPool.shutdown();
        }
    }
}

结果都是，5秒后done：