Java ThreadGroup setMaxPriority() 方法及示例

 Java ThreadGroup 类

说明

Java ThreadGroup setMaxPriority()方法设置组的最大优先级。线程组中已经具有更高优先级的线程不受影响。

声明

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

public final void setMaxPriority(int priority)

参数

priority 这是线程组的新优先级。

返回值

此方法不返回任何值。

异常

SecurityException 如果当前线程无法修改此线程组。

示例 1

以下示例显示用法对于单个 ThreadGroup 对象，ThreadGroup 的 setMaxPriority() 方法。我们创建了一个 ThreadGroup 对象并为其分配了一个名称。然后我们使用之前创建的线程组对象创建了两个线程。使用 setMaxPriority()，我们将最大优先级设置为普通优先级。使用 getMaxPriority() 方法，我们获得线程组对象的最大优先级。

package com.yxjc123;

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

   public void start() {
      try {     
         //创建一个ThreadGroup
         ThreadGroup threadGroup = new ThreadGroup("ThreadGroup");
         threadGroup.setMaxPriority(Thread.NORM_PRIORITY);
         //创建一个线程
         Thread t1 = new Thread(threadGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         //创建另一个线程
         Thread t2 = new Thread(threadGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();

         //返回线程组的最大优先级
         int i = threadGroup.getMaxPriority();
         System.out.println("Maximum priority of threadGroup =" + i);

         // 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...
Maximum priority of threadGroup =5
Thread-0 finished executing.
Thread-1 finished executing.

示例 2

以下示例显示了在多个 ThreadGroup 对象的情况下 ThreadGroup setMaxPriority() 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。使用setMaxPriority()，我们将子线程组的最大优先级设置为普通优先级()。使用 getMaxPriority() 方法，我们打印每个线程组对象的最大优先级。

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");
         cThreadGroup.setMaxPriority(Thread.NORM_PRIORITY);
         //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();

         //返回线程组的最大优先级
         int i = pThreadGroup.getMaxPriority();
         System.out.println("Maximum priority of pThreadGroup =" + i);

         i = cThreadGroup.getMaxPriority();
         System.out.println("Maximum priority of cThreadGroup =" + i);
         // 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...
Maximum priority of pThreadGroup =10
Maximum priority of cThreadGroup =5
Thread-0 finished executing.
Thread-1 finished executing.

示例 3

以下示例显示了 ThreadGroup getMaxPriority() 方法在子 ThreadGroup 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。使用 setMaxPriority()，我们将父线程组的最大优先级设置为普通优先级() 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 getMaxPriority() 方法，我们打印每个线程组对象的最大优先级。这里我们可以看到子线程组和祖先线程组继承了父线程组对象的最大优先级。

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");
		 pThreadGroup.setMaxPriority(Thread.NORM_PRIORITY);
         //为父ThreadGroup创建子ThreadGroup
         ThreadGroup cThreadGroup = new ThreadGroup(pThreadGroup, "Child ThreadGroup");
		 
         //为父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();
            
         //返回线程组的最大优先级
         int i = pThreadGroup.getMaxPriority();
         System.out.println("Maximum priority of pThreadGroup =" + i);

         i = cThreadGroup.getMaxPriority();
         System.out.println("Maximum priority of cThreadGroup =" + i);

         i = gThreadGroup.getMaxPriority();
         System.out.println("Maximum priority of gThreadGroup =" + i);

         // 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，这将产生以下结果结果 -

Starting Thread-0...
Starting Thread-1...
Maximum priority of pThreadGroup =5
Maximum priority of cThreadGroup =5
Maximum priority of gThreadGroup =5
Thread-0 finished executing.
Thread-1 finished executing.