Java线程总结（二）

自定义线程的数据可以共享，也可以不共享，这要看具体的实现方式。

1.不共享数据多线程实现方式：

public class MyThread  extends Thread{
    private int count = 4;

    public MyThread(String threadName){
        this.setName(threadName);
    }

    @Override
    public void run(){
        while (count > 0){
            count = count - 1;
            System.out.println("由 " + Thread.currentThread().getName() + " 计算，count = " + count);
            try {
                Thread.sleep(1000);
            }catch (InterruptedException e){
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        MyThread threadA = new MyThread("A");
        MyThread threadB = new MyThread("B");
        MyThread threadC = new MyThread("C");
        threadA.start();
        threadB.start();
        threadC.start();
    }
}

执行结果如下：

从结果上看，每个线程都是都是先打印3，再打印2，然后是1，0。由此可知各个线程都有一份变量count，不受其他线程的干扰。

2. 共享数据的多线程实现方式

public class MyThread  extends Thread{
    private int count = 4;

    @Override
    public void run(){
        while (count > 0){
            count = count - 1;
            System.out.println("由 " + Thread.currentThread().getName() + " 计算，count = " + count);
            try {
                Thread.sleep(1000);
            }catch (InterruptedException e){
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        MyThread myThread = new MyThread();
        Thread a = new Thread(myThread,"A");
        Thread b = new Thread(myThread,"B");
        Thread c = new Thread(myThread,"C");
        Thread d = new Thread(myThread,"D");
        a.start();
        b.start();
        c.start();
        d.start();
    }
}

执行结果如下：

由结果可知，A，B，C，D四个线程共享变量count