![java package tutorial](/java/lang/images/java.jpg)
- Java.lang 包类
- Java.lang - 首页
- Java.lang - Boolean
- Java.lang - Byte
- Java.lang - Character
- Java.lang - Character.Subset
- Java.lang - Character.UnicodeBlock
- Java.lang - Class
- Java.lang - ClassLoader
- Java.lang - Compiler
- Java.lang - Double
- Java.lang - Enum
- Java.lang - Float
- Java.lang - InheritableThreadLocal
- Java.lang - Integer
- Java.lang - Long
- Java.lang - Math
- Java.lang - Number
- Java.lang - Object
- Java.lang - Package
- Java.lang - Process
- Java.lang - ProcessBuilder
- Java.lang - Runtime
- Java.lang - RuntimePermission
- Java.lang - SecurityManager
- Java.lang - Short
- Java.lang - StackTraceElement
- Java.lang - StrictMath
- Java.lang - String
- Java.lang - StringBuffer
- Java.lang - StringBuilder
- Java.lang - System
- Java.lang - Thread
- Java.lang - ThreadGroup
- Java.lang - ThreadLocal
- Java.lang - Throwable
- Java.lang - Void
- Java.lang 包额外内容
- Java.lang - 接口
- Java.lang - 错误
- Java.lang - 异常
- Java.lang 包实用资源
- Java.lang - 实用资源
- Java.lang - 讨论
Java - ThreadGroup isDaemon() 方法
描述
Java ThreadGroup isDaemon() 方法测试此线程组是否为守护线程组。当守护线程组的最后一个线程停止或其最后一个线程组被销毁时,它将自动被销毁。
声明
以下是 java.lang.ThreadGroup.isDaemon() 方法的声明
public final boolean isDaemon()
参数
无
返回值
如果此线程组是守护线程组,则此方法返回 true,否则返回 false。
异常
无
在 ThreadGroup 对象中检查守护线程示例
以下示例显示了在单个 ThreadGroup 对象的情况下使用 ThreadGroup isDaemon() 方法的情况。我们创建了一个 ThreadGroup 对象并为其分配了一个名称。然后,我们使用前面创建的线程组对象创建了两个线程。使用 isDaemon() 方法,我们获取此线程组对象的父级的状态,该状态默认为 false。
package com.tutorialspoint; public class ThreadGroupDemo implements Runnable { public static void main(String[] args) { ThreadGroupDemo tg = new ThreadGroupDemo(); tg.start(); } public void start() { try { // create a ThreadGroup ThreadGroup threadGroup = new ThreadGroup("ThreadGroup"); // create a thread Thread t1 = new Thread(threadGroup, this); System.out.println("Starting " + t1.getName() + "..."); t1.start(); // create another thread Thread t2 = new Thread(threadGroup, this); System.out.println("Starting " + t2.getName() + "..."); t2.start(); // returns the status of thread group boolean isDaemon = threadGroup.isDaemon(); System.out.println("Status of the threadGroup = " + isDaemon); // block until the other threads finish t1.join(); t2.join(); } catch (InterruptedException ex) { System.out.println(ex.toString()); } } // implements run() public void run() { for(int i = 0; i < 4;i++) { i++; try { Thread.sleep(50); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } System.out.println(Thread.currentThread().getName() + " finished executing."); } }
输出
让我们编译并运行上述程序,这将产生以下结果:
Starting Thread-0... Starting Thread-1... Status of the threadGroup = false Thread-1 finished executing. Thread-0 finished executing.
在多个 ThreadGroup 对象中检查守护线程示例
以下示例显示了在多个 ThreadGroup 对象的情况下使用 ThreadGroup isDaemon() 方法的情况。我们创建了一个 ThreadGroup 对象并为其分配了一个名称。接下来,我们创建了一个子 ThreadGroup 对象。然后,我们使用前面创建的线程组对象创建了两个线程。使用 isDaemon() 方法,我们打印每个线程组对象的状态。
package com.tutorialspoint; public class ThreadGroupDemo implements Runnable { public static void main(String[] args) { ThreadGroupDemo tg = new ThreadGroupDemo(); tg.start(); } public void start() { try { // create a parent ThreadGroup ThreadGroup pThreadGroup = new ThreadGroup("parent ThreadGroup"); // create a child ThreadGroup for parent ThreadGroup ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "child ThreadGroup"); // create a thread Thread t1 = new Thread(pThreadGroup, this); System.out.println("Starting " + t1.getName() + "..."); t1.start(); // create another thread Thread t2 = new Thread(cThreadGroup, this); System.out.println("Starting " + t2.getName() + "..."); t2.start(); // returns the status of thread group System.out.println("Status of pThreadGroup = " + pThreadGroup.isDaemon()); System.out.println("Status of cThreadGroup = " + cThreadGroup.isDaemon()); // block until the other threads finish t1.join(); t2.join(); } catch (InterruptedException ex) { System.out.println(ex.toString()); } } // implements run() public void run() { for(int i = 0; i < 4;i++) { i++; try { Thread.sleep(50); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } System.out.println(Thread.currentThread().getName() + " finished executing."); } }
输出
让我们编译并运行上述程序,这将产生以下结果:
Starting Thread-0... Starting Thread-1... Status of pThreadGroup = false Status of cThreadGroup = false Thread-1 finished executing. Thread-0 finished executing.
在子/孙 ThreadGroup 对象中检查守护线程示例
以下示例显示了在子线程组和孙线程组对象的情况下使用 ThreadGroup isDaemon() 方法的情况。我们创建了一个 ThreadGroup 对象并为其分配了一个名称。接下来,我们创建了一个子 ThreadGroup 对象。然后,我们使用前面创建的子线程组和孙线程组对象创建了两个线程。使用 isDaemon() 方法,我们打印每个线程组对象的状态。
package com.tutorialspoint; public class ThreadGroupDemo implements Runnable { public static void main(String[] args) { ThreadGroupDemo tg = new ThreadGroupDemo(); tg.start(); } public void start() { try { // create a parent ThreadGroup ThreadGroup pThreadGroup = new ThreadGroup("Parent ThreadGroup"); // create a child ThreadGroup for parent ThreadGroup ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "Child ThreadGroup"); // create a grandchild ThreadGroup for parent ThreadGroup ThreadGroup gThreadGroup = new ThreadGroup(cThreadGroup, "GrandChild ThreadGroup"); // create a thread Thread t1 = new Thread(cThreadGroup, this); System.out.println("Starting " + t1.getName() + "..."); t1.start(); // create another thread Thread t2 = new Thread(gThreadGroup, this); System.out.println("Starting " + t2.getName() + "..."); t2.start(); // returns the status of thread group System.out.println("Status of pThreadGroup = " + pThreadGroup.isDaemon()); System.out.println("Status of cThreadGroup = " + cThreadGroup.isDaemon()); System.out.println("Status of gThreadGroup = " + gThreadGroup.isDaemon()); // block until the other threads finish t1.join(); t2.join(); } catch (InterruptedException ex) { System.out.println(ex.toString()); } } // implements run() public void run() { for(int i = 0; i < 4;i++) { i++; try { Thread.sleep(50); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } System.out.println(Thread.currentThread().getName() + " finished executing."); } }
输出
让我们编译并运行上述程序,这将产生以下结果:
Starting Thread-0... Starting Thread-1... Status of pThreadGroup = false Status of cThreadGroup = false Status of gThreadGroup = false Thread-0 finished executing. Thread-1 finished executing.