分享Java多线程实现的四种方式

class MyThread extends Thread {
    private int i = 0;

    @Override
    public void run() {
        for (i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + " " + i);
        }
    }
}
public class ThreadDemo1 {
    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + " " + i);
            if (i == 30) {
                // 创建一个新的线程  myThread1  此线程进入新建状态
                Thread myThread1 = new MyThread();
                // 创建一个新的线程 myThread2 此线程进入新建状态
                Thread myThread2 = new MyThread();
                // 调用start()方法使得线程进入就绪状态
                myThread1.start();
                // 调用start()方法使得线程进入就绪状态
                myThread2.start();
            }
        }
    }
}

class MyRunnable implements Runnable {
    private int i = 0;
    @Override
    public void run() {
        for (i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + " " + i);
        }
    }
}
public class ThreadDemo2 {
    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + " " + i);
            if (i == 30) {
                // 创建一个Runnable实现类的对象
                Runnable myRunnable = new MyRunnable();
                // 将myRunnable作为Thread target创建新的线程
                Thread thread1 = new Thread(myRunnable);
                Thread thread2 = new Thread(myRunnable);
                // 调用start()方法使得线程进入就绪状态
                thread1.start();
                thread2.start();
            }
        }
    }
}

public class ThreadDemo3 {
    public static void main(String[] args) {
        // 创建MyCallable对象
        Callable<Integer> myCallable = new MyCallable();
        //使用FutureTask来包装MyCallable对象
        FutureTask<Integer> ft = new FutureTask<Integer>(myCallable);

        for (int i = 0; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + " " + i);
            if (i == 30) {
                //FutureTask对象作为Thread对象的target创建新的线程
                Thread thread = new Thread(ft);
                //线程进入到就绪状态
                thread.start();
            }
        }

        System.out.println("主线程for循环执行完毕..");

        try {
            //取得新创建的新线程中的call()方法返回的结果
            int sum = ft.get();
            System.out.println("sum = " + sum);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
}
class MyCallable implements Callable<Integer> {
    private int i = 0;

    // 与run()方法不同的是，call()方法具有返回值
    @Override
    public Integer call() {
        int sum = 0;
        for (; i < 100; i++) {
            System.out.println(Thread.currentThread().getName() + " " + i);
            sum += i;
        }
        return sum;
    }
}

public class ThreadDemo4{
    //线程池数量 
    private static int POOL_NUM = 10;
    /**
     * @param args
     * @throws InterruptedException
     */
    public static void main(String[] args) throws InterruptedException {
        // TODO Auto-generated method stub 
        ExecutorService executorService = Executors.newFixedThreadPool(5);
        for(int i = 0; i<POOL_NUM; i++) {
            RunnableThread thread = new RunnableThread();
            //Thread.sleep(1000); 
            executorService.execute(thread);
        }
        //关闭线程池 
        executorService.shutdown();
    }
}

class RunnableThread implements Runnable {
    @Override
    public void run() {
        System.out.println("通过线程池方式创建的线程：" + Thread.currentThread().getName() + " ");
    }
}