自定義線程的數據可以共享，也可以不共享，這要看具體的實現方式。

1.不共享數據多線程實現方式：

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() + " 計算，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();
    }
}

執行結果如下：

從結果上看，每個線程都是都是先打印3，再打印2，然後是1，0。由此可知各個線程都有一份變量count，不受其他線程的幹擾。

2. 共享數據的多線程實現方式

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() + " 計算，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();
    }
}

執行結果如下：

由結果可知，A，B，C，D四個線程共享變量count

Java線程總結（二）