Java Java.lang.ThreadGroup.setMaxPriority()用法及代碼示例

描述

這個java.lang.ThreadGroup.setMaxPriority()方法設置組的最大優先級。線程組中已經具有更高優先級的線程不受影響。

聲明

以下是聲明java.lang.ThreadGroup.setMaxPriority()方法

public final void setMaxPriority(int pri)

參數

pri- 這是線程組的新優先級。

返回值

此方法不返回任何值。

異常

SecurityException- 如果當前線程不能修改這個線程組。

示例

下麵的例子展示了 java.lang.ThreadGroup.setMaxPriority() 方法的用法。

package com.tutorialspoint;

import java.lang.*;

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

   public void func() {
      try {     
         // create a parent ThreadGroup
         ThreadGroup pGroup = new ThreadGroup("Parent ThreadGroup");
         // set maximum priority as 8 for Parent
         pGroup.setMaxPriority(Thread.MAX_PRIORITY - 2);
    
         // create a child ThreadGroup for parent ThreadGroup
         ThreadGroup cGroup = new ThreadGroup(pGroup, "Child ThreadGroup");
         // set maximum priority as 5 for child
         cGroup.setMaxPriority(Thread.NORM_PRIORITY);

         // create a thread with Priority as MAX
         Thread t1 = new Thread(pGroup, this);
         t1.setPriority(Thread.MAX_PRIORITY);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         // create another thread with Priority as MAX
         Thread t2 = new Thread(cGroup, this);
         t1.setPriority(Thread.MAX_PRIORITY);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();
            
         // display the number of active threads with actual priority
         System.out.println("Active threads in \"" + pGroup.getName() 
            + "\" = " + pGroup.activeCount());

         // 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 < 1000;i++) {
         i++;
      }
      System.out.println(Thread.currentThread().getName() +
         " [priority = " + Thread.currentThread().getPriority() +
         "] finished executing.");
   }
}

讓我們編譯並運行上麵的程序，這將產生以下結果 -

Starting Thread-0...
Starting Thread-1...
Active threads in group "Parent ThreadGroup" = 2
Thread-0 [priority = 8] finished executing.
Thread-1 [priority = 5] finished executing.