Java主線程與子線程

Java 實例 - 獲取所有線程

Daemon線程——在所有的非Daemon線程結束后JVM會停止。利用Daemon線程的特性，不停輸出目前運行的線程，然后判斷主線程與子線程的關系。

似乎主線程結束后，子線程還在繼續的樣子，但我並不能確定。

附上代碼

public class ThreadDemo {
    public static void main(String[] args) {
        System.out.println("start-當前活動的線程數" + Thread.activeCount());
        {
            ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();
            int noThreads = currentGroup.activeCount();
            Thread[] lstThreads = new Thread[noThreads];
            currentGroup.enumerate(lstThreads);
            for (int i = 0; i < noThreads; i++)
                System.out.println("線程號：" + i + " = " + lstThreads[i].getName());
            System.out.println();
        }

        Thread thread = new Thread("thread") {
            @Override
            public void run() {
                System.out.println("thread over");
            }
        };

        Thread daemon = new Thread("daemon") {
            @Override
            public synchronized void run() {
                while (true) {
//                thread.isAlive();
//                System.out.println("當前活動的線程數"+Thread.activeCount());
                    {
                        ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();
                        int noThreads = currentGroup.activeCount();
                        Thread[] lstThreads = new Thread[noThreads];
                        currentGroup.enumerate(lstThreads);
                        for (int i = 0; i < noThreads; i++)
                            System.out.println("線程號：" + i + " = " + lstThreads[i].getName());
                        System.out.println();
                    }
                }
            }
        };
        daemon.setDaemon(true);

        daemon.start();
        thread.start();

        System.out.println("end-當前活動的線程數" + Thread.activeCount());
        {
            ThreadGroup currentGroup = Thread.currentThread().getThreadGroup();
            int noThreads = currentGroup.activeCount();
            Thread[] lstThreads = new Thread[noThreads];
            currentGroup.enumerate(lstThreads);
            for (int i = 0; i < noThreads; i++)
                System.out.println("線程號：" + i + " = " + lstThreads[i].getName());
            System.out.println();
        }
    }
}