如何在java中给出默认的新线程名？

Question

当我运行这个程序时

public class Fabric extends Thread {
    public static void main(String[] args) {
        Thread t1 = new Thread(new Fabric());
        Thread t2 = new Thread(new Fabric());
        Thread t3 = new Thread(new Fabric());
        t1.start();
        t2.start();
        t3.start();
    }
    public void run() {
        for(int i = 0; i < 2; i++)
        System.out.print(Thread.currentThread().getName() + " ");
    }
}

我得到输出

Thread-1 Thread-5 Thread-5 Thread-3 Thread-1 Thread-3

有什么特别的理由让线程命名为奇数- 1，3，5.或者是不可预测的？

Answer 1

new Thread(new Fabric());

因为Fabric是一个线程，所以您在这里创建了两个线程:)

JDK8代码：

/* For autonumbering anonymous threads. */
private static int threadInitNumber;
private static synchronized int nextThreadNum() {
    return threadInitNumber++;
}

Answer 2

线程名称中的默认数值是一个递增的值，除非在创建线程时指定了名称。Fabric扩展了Thread，您正在传递Fabric实例来创建另一个线程--因此，在进程中创建2个线程时，内部线程计数器会增加两次。

Answer 3

如果您像下面这样更改程序，您将得到线程编号的顺序。

    public class Fabric extends Thread {
    public static void main(String[] args) {
        Thread t1 = new Fabric();
        Thread t2 = new Fabric();
        Thread t3 = new Fabric();
        t1.start();
        t2.start();
        t3.start();
    }
    public void run() {
        for(int i = 0; i < 2; i++)
            System.out.print(Thread.currentThread().getName() + " ");
    }
}

输出是

Thread-0 Thread-2 Thread-2 Thread-1 Thread-0 Thread-1