Java ThreadGroup ParentOf() 方法及示例

 Java ThreadGroup 类

说明

Java ThreadGroup ParentOf() 方法测试此线程组是否是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 这是一个线程组。

返回值

如果该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

示例 1

以下示例显示 ThreadGroup ParentOf() 方法在以下情况下的用法多个 ThreadGroup 对象。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。然后我们使用之前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.yxjc123;

public class ThreadGroupDemo implements Runnable {
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.start();
   }

   public void start() {
      try {     
         //创建父ThreadGroup
         ThreadGroup pThreadGroup = new ThreadGroup("parent ThreadGroup");
		 
         //为父ThreadGroup创建子ThreadGroup
         ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "child ThreadGroup");

         //创建一个线程
         Thread t1 = new Thread(pThreadGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         //创建另一个线程
         Thread t2 = new Thread(cThreadGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();

         //判断哪个ThreadGroup是父线程组
         boolean isParent = pThreadGroup.parentOf(cThreadGroup);
         System.out.println(pThreadGroup.getName() + " is the parent of "
            + cThreadGroup.getName() + "? " + isParent);
         
         // 阻塞直到其他线程完成
         t1.join();
         t2.join();

      } catch (InterruptedException ex) {
         System.out.println(ex.toString());
      }
   }

   // 实现 run()
   public void run() {

      for(int i = 0; i < 4;i++) {
         i++;
         try {
			Thread.sleep(50);
		} catch (InterruptedException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}
      }
      System.out.println(Thread.currentThread().getName() + " finished executing.");
   }
} 

输出

让我们编译并运行上面的程序，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.

示例 2

以下示例显示了在多个 ThreadGroup 对象的情况下 ThreadGroupparentOf() 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。然后我们使用之前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.yxjc123;

public class ThreadGroupDemo implements Runnable {
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.start();
   }

   public void start() {
      try {     
         //创建父ThreadGroup
         ThreadGroup pThreadGroup = new ThreadGroup("parent ThreadGroup");
		 
         //为父ThreadGroup创建子ThreadGroup
         ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "child ThreadGroup");

         //创建一个线程
         Thread t1 = new Thread(pThreadGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         //创建另一个线程
         Thread t2 = new Thread(cThreadGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();

         //判断哪个ThreadGroup是父线程组
         boolean isParent = cThreadGroup.parentOf(pThreadGroup);
         System.out.println(cThreadGroup.getName() + " is the parent of "
            + pThreadGroup.getName() + "? " + isParent);
         
         // 阻塞直到其他线程完成
         t1.join();
         t2.join();

      } catch (InterruptedException ex) {
         System.out.println(ex.toString());
      }
   }

   // 实现 run()
   public void run() {

      for(int i = 0; i < 4;i++) {
         i++;
         try {
			Thread.sleep(50);
		} catch (InterruptedException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}
      }
      System.out.println(Thread.currentThread().getName() + " finished executing.");
   }
} 

输出

让我们编译并运行上面的程序，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.

示例 3

以下示例显示了 ThreadGroup ParentOf() 方法在子 ThreadGroup 对象和孙 ThreadGroup 对象的情况下的用法。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，我们使用之前创建的子线程组对象和孙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名称。

package com.yxjc123;

public class ThreadGroupDemo implements Runnable {
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.start();
   }

   public void start() {
      try {     
         //创建父ThreadGroup
         ThreadGroup pThreadGroup = new ThreadGroup("parent ThreadGroup");
		 
         //为父ThreadGroup创建子ThreadGroup
         ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "child ThreadGroup");
		 
         //为子ThreadGroup创建孙ThreadGroup
         ThreadGroup gThreadGroup = new ThreadGroup(cThreadGroup, "grandchild ThreadGroup");

         //创建一个线程
         Thread t1 = new Thread(cThreadGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         //创建另一个线程
         Thread t2 = new Thread(gThreadGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();

         //判断哪个ThreadGroup是父线程组
         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);
         
		 // 阻塞直到其他线程完成
         t1.join();
         t2.join();

      } catch (InterruptedException ex) {
         System.out.println(ex.toString());
      }
   }

   // 实现 run()
   public void run() {

      for(int i = 0; i < 4;i++) {
         i++;
         try {
			Thread.sleep(50);
		} catch (InterruptedException e) {
			// TODO 自动生成的 catch 块
			e.printStackTrace();
		}
      }
      System.out.println(Thread.currentThread().getName() + " finished executing.");
   }
} 

输出

让我们编译并运行上面的程序，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.