線程組能夠批量管理線程和線程組對象。java
例子以下,創建一級關聯。this
public class MyThread43 implements Runnable{ public void run() { try { while (!Thread.currentThread().isInterrupted()) { System.out.println("ThreadName = " + Thread.currentThread().getName()); Thread.sleep(3000); } } catch (InterruptedException e) { e.printStackTrace(); } } public static void main(String[] args) { MyThread43 mt0 = new MyThread43(); MyThread43 mt1 = new MyThread43(); ThreadGroup tg = new ThreadGroup("新建線程組1"); Thread t0 = new Thread(tg, mt0); Thread t1 = new Thread(tg, mt1); t0.start(); t1.start(); System.out.println("活動的線程數爲:" + tg.activeCount()); System.out.println("線程組的名稱爲:" + tg.getName()); } }
輸出結果以下線程
活動的線程數爲:2 線程組的名稱爲:新建線程組1 ThreadName = Thread-0 ThreadName = Thread-1 ThreadName = Thread-0 ThreadName = Thread-1 ThreadName = Thread-1 ThreadName = Thread-0 ThreadName = Thread-1 ThreadName = Thread-0 ······
每隔三秒輸出兩個線程名稱,符合預期。code
public class ThreadDomain49 { public static void main(String[] args) { System.out.println("A處線程:" + Thread.currentThread().getName() + ", 所屬線程:" + Thread.currentThread().getThreadGroup().getName() + ", 組中有線程組數量:" + Thread.currentThread().getThreadGroup().activeGroupCount()); ThreadGroup group = new ThreadGroup("新的組"); System.out.println("B處線程:" + Thread.currentThread().getName() + ", 所屬線程:" + Thread.currentThread().getThreadGroup().getName() + ", 組中有線程組數量:" + Thread.currentThread().getThreadGroup().activeGroupCount()); ThreadGroup[] tg = new ThreadGroup[Thread.currentThread().getThreadGroup().activeGroupCount()]; Thread.currentThread().getThreadGroup().enumerate(tg); for (int i = 0; i < tg.length; i++) System.out.println("第一個線程組名稱爲:" + tg[i].getName()); } }
輸出結果以下對象
A處線程:main, 所屬線程:main, 組中有線程組數量:0 B處線程:main, 所屬線程:main, 組中有線程組數量:1 第一個線程組名稱爲:新的組
沒有指定線程組,則歸屬到當前線程所屬的組。blog
public class ThreadDomain50 { public static void main(String[] args) { System.out.println(Thread.currentThread().getThreadGroup().getParent().getName()); System.out.println(Thread.currentThread().getThreadGroup().getParent().getParent().getName()); } }
運行結果get
system Exception in thread "main" java.lang.NullPointerException at com.advance.MultiThread3.MyThread.ThreadDomain50.main(ThreadDomain50.java:14)
當前線程的線程組的父線程組是系統線程組;系統線程組的父線程組不存在;系統線程組就是根線程組。io
批量中止組內線程
請看示例class
public class MyThread44 extends Thread{ public MyThread44(ThreadGroup tg, String name) { super(tg, name); } public void run() { System.out.println("ThreadName = " + Thread.currentThread().getName() + "準備開始死循環了"); while (!this.isInterrupted()){} System.out.println("ThreadName = " + Thread.currentThread().getName() + "結束了"); } public static void main(String[] args) throws InterruptedException { ThreadGroup tg = new ThreadGroup("個人線程組"); MyThread44 mt = null; for (int i = 0; i < 3; i++) { mt = new MyThread44(tg, "線程" + i); mt.start(); } Thread.sleep(5000); tg.interrupt(); System.out.println("調用了interrupt()方法"); } }
輸出結果以下thread
ThreadName = 線程0準備開始死循環了 ThreadName = 線程1準備開始死循環了 ThreadName = 線程2準備開始死循環了 調用了interrupt()方法 ThreadName = 線程0結束了 ThreadName = 線程2結束了 ThreadName = 線程1結束了
能夠看到,ThreadGroup的interrupt方法批量中斷線程組的線程。