Java - ThreadGroup 的 list() 方法

描述

Java ThreadGroup 的 list() 方法將有關此執行緒組的資訊列印到標準輸出。這僅對除錯有用。

宣告

以下是 java.lang.ThreadGroup.list() 方法的宣告

public void list()

引數

無

返回值

此方法不返回值。

異常

無

列印單個 ThreadGroup 物件的除錯資訊示例

以下示例顯示了在單個 ThreadGroup 物件的情況下使用 ThreadGroup list() 方法的情況。我們建立了一個 ThreadGroup 物件併為其指定了一個名稱。然後，我們使用前面建立的執行緒組物件建立了兩個執行緒。使用 list() 方法，我們獲取了此執行緒組物件的的資訊。

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();

         // print the details of the thread group
         threadGroup.list();

         // 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.");
   }
} 

輸出

讓我們編譯並執行上述程式，這將產生以下結果：

Starting Thread-0...
Starting Thread-1...
java.lang.ThreadGroup[name=ThreadGroup,maxpri=10]
    Thread[Thread-0,5,ThreadGroup]
    Thread[Thread-1,5,ThreadGroup]
Thread-1 finished executing.
Thread-0 finished executing.

列印多個 ThreadGroup 物件的除錯資訊示例

以下示例顯示了在多個 ThreadGroup 物件的情況下使用 ThreadGroup list() 方法的情況。我們建立了一個 ThreadGroup 物件併為其指定了一個名稱。接下來，我們建立了一個子 ThreadGroup 物件。然後，我們使用前面建立的執行緒組物件建立了兩個執行緒。使用 list() 方法，我們列印每個執行緒組物件的資訊。

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();

         // print the details of the thread groups
         pThreadGroup.list();
         cThreadGroup.list();
         
         // 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.");
   }
} 

輸出

讓我們編譯並執行上述程式，這將產生以下結果：

Starting Thread-0...
Starting Thread-1...
java.lang.ThreadGroup[name=parent ThreadGroup,maxpri=10]
    Thread[Thread-0,5,parent ThreadGroup]
    java.lang.ThreadGroup[name=child ThreadGroup,maxpri=10]
        Thread[Thread-1,5,child ThreadGroup]
java.lang.ThreadGroup[name=child ThreadGroup,maxpri=10]
    Thread[Thread-1,5,child ThreadGroup]
Thread-0 finished executing.
Thread-1 finished executing.

列印子/孫 ThreadGroup 物件的除錯資訊示例

以下示例顯示了在子執行緒組和孫執行緒組物件的情況下使用 ThreadGroup list() 方法的情況。我們建立了一個 ThreadGroup 物件併為其指定了一個名稱。接下來，我們建立了一個子 ThreadGroup 物件。然後，我們使用前面建立的子執行緒組和孫執行緒組物件建立了兩個執行緒。使用 list() 方法，我們列印每個執行緒組物件的父物件名稱。

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();
            
         // print the details of the thread groups
         pThreadGroup.list();
         cThreadGroup.list();
         gThreadGroup.list();

         // 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.");
   }
} 

輸出

讓我們編譯並執行上述程式，這將產生以下結果：

Starting Thread-0...
Starting Thread-1...
java.lang.ThreadGroup[name=Parent ThreadGroup,maxpri=10]
    java.lang.ThreadGroup[name=Child ThreadGroup,maxpri=10]
        Thread[Thread-0,5,Child ThreadGroup]
        java.lang.ThreadGroup[name=GrandChild ThreadGroup,maxpri=10]
            Thread[Thread-1,5,GrandChild ThreadGroup]
java.lang.ThreadGroup[name=Child ThreadGroup,maxpri=10]
    Thread[Thread-0,5,Child ThreadGroup]
    java.lang.ThreadGroup[name=GrandChild ThreadGroup,maxpri=10]
        Thread[Thread-1,5,GrandChild ThreadGroup]
java.lang.ThreadGroup[name=GrandChild ThreadGroup,maxpri=10]
    Thread[Thread-1,5,GrandChild ThreadGroup]
Thread-1 finished executing.
Thread-0 finished executing.