Java - ThreadGroup parentOf() 方法

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描述

Java ThreadGroup parentOf() 方法测试此线程组是否为线程组参数或其祖先线程组之一。

声明

以下是java.lang.ThreadGroup.parentOf() 方法的声明

public final boolean parentOf(ThreadGroup g)

参数

g − 一个线程组。

返回值

如果此线程组是线程组参数或其祖先线程组之一，则此方法返回 true；否则返回 false。

异常

无

检查 ThreadGroup 对象的父级示例

以下示例演示了在 ThreadGroup 对象的情况下 ThreadGroup parentOf() 方法的用法。我们创建了一个父 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 parentOf() 方法，我们打印子线程组对象的父级检查。

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();

         // determine which ThreadGroup is parent
         boolean isParent = pThreadGroup.parentOf(cThreadGroup);
         System.out.println(pThreadGroup.getName() + " is the parent of "
            + cThreadGroup.getName() + "? " + isParent);
         
         // 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...
parent ThreadGroup is the parent of child ThreadGroup? true
Thread-1 finished executing.
Thread-0 finished executing.

检查多个 ThreadGroup 对象的父级示例

以下示例演示了在多个 ThreadGroup 对象的情况下 ThreadGroup parentOf() 方法的用法。我们创建了一个父 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 parentOf() 方法，我们打印父线程组对象的父级检查。

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();

         // determine which ThreadGroup is parent
         boolean isParent = cThreadGroup.parentOf(pThreadGroup);
         System.out.println(cThreadGroup.getName() + " is the parent of "
            + pThreadGroup.getName() + "? " + isParent);
         
         // 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...
child ThreadGroup is the parent of parent ThreadGroup? false
Thread-1 finished executing.
Thread-0 finished executing.

检查子/孙子 ThreadGroup 对象的父级示例

以下示例演示了在子线程组和孙子线程组的情况下 ThreadGroup parentOf() 方法的用法。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子线程组对象创建了两个线程。使用 parentOf() 方法，我们打印每个线程组对象的父级的名称。

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 child 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();

         // determine which ThreadGroup is parent
         boolean isParent = pThreadGroup.parentOf(cThreadGroup);
         System.out.println(pThreadGroup.getName() + " is the parent of "
            + cThreadGroup.getName() + "? " + isParent);
			
         isParent = pThreadGroup.parentOf(gThreadGroup);
         System.out.println(pThreadGroup.getName() + " is the parent of "
            + gThreadGroup.getName() + "? " + isParent);
         
		 // 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...
parent ThreadGroup is the parent of child ThreadGroup? true
parent ThreadGroup is the parent of grandchild ThreadGroup? true
Thread-1 finished executing.
Thread-0 finished executing.
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