Java – 執行緒命名及示例

在實現 Runnable 介面時命名執行緒

如果您的類旨在作為執行緒執行並實現Runnable介面，則需要使用以下建構函式例項化Thread物件：

Thread(Runnable threadObj, String threadName);

其中，threadObj是實現Runnable介面的類的例項，threadName是賦予新執行緒的名稱。

建立 Thread 物件後，您可以透過呼叫start()方法啟動它，該方法會呼叫run()方法。以下是start()方法的簡單語法：

void start();

示例

在這個例子中，我們透過實現Runnable介面建立一個RunnableDemo類。RunnableDemo類具有run()方法的實現。在主類TestThread中，我們建立了RunnableDemo物件，並使用這些物件建立了兩個Thread物件。當在每個執行緒物件上呼叫Thread.start()方法時，執行緒開始處理，程式開始執行。

package com.tutorialspoint;
class RunnableDemo implements Runnable {
   private String threadName;
   RunnableDemo( String name) {
      threadName = name;
      System.out.println("Thread: " + threadName + ", " + "State: New");
   }
   public void run() {
      System.out.println("Thread: " + threadName + ", " + "State: Running");
      for(int i = 4; i > 0; i--) {
         System.out.println("Thread: " + threadName + ", " + i);         
      }
      System.out.println("Thread: " + threadName + ", " + "State: Dead");
   }
}
public class TestThread {
   public static void main(String args[]) {
	  RunnableDemo runnableDemo1 = new RunnableDemo( "Thread-1");
	  RunnableDemo runnableDemo2 = new RunnableDemo( "Thread-2");
	  
	  Thread thread1 = new Thread(runnableDemo1);
	  Thread thread2 = new Thread(runnableDemo2);
	
	  thread1.start();
	  thread2.start();
   }
}

輸出

Thread: Thread-1, State: New
Thread: Thread-2, State: New
Thread: Thread-1, State: Running
Thread: Thread-1, 4
Thread: Thread-1, 3
Thread: Thread-1, 2
Thread: Thread-1, 1
Thread: Thread-1, State: Dead
Thread: Thread-2, State: Running
Thread: Thread-2, 4
Thread: Thread-2, 3
Thread: Thread-2, 2
Thread: Thread-2, 1
Thread: Thread-2, State: Dead

擴充套件 Thread 類時命名執行緒

建立執行緒的第二種方法是建立一個擴充套件Thread類的新的類。這種方法在處理使用Thread類中可用方法建立的多個執行緒時提供了更大的靈活性。為了命名執行緒，我們需要使用名稱呼叫超類Thread建構函式。

class ThreadDemo extends Thread {
   ThreadDemo( String name) {
      super(name);
      ...
   }
...
}

示例 1

以下是重寫為擴充套件Thread的前面程式：在這個例子中，我們建立了一個ThreadDemo類，它擴充套件了Thread類。我們在constructor()方法中呼叫super(name)來為執行緒分配名稱，並呼叫super.start()來啟動執行緒處理。

package com.tutorialspoint;
class ThreadDemo extends Thread {
   ThreadDemo( String name) {
	  super(name);
      System.out.println("Thread: " + name + ", " + "State: New");
   }
   public void run() {
      System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Running");
      for(int i = 4; i > 0; i--) {
         System.out.println("Thread: " + Thread.currentThread().getName() + ", " + i); 
      }
      System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Dead");
   }

   public void start () {
      System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Start");
      super.start();
   }
}
public class TestThread {
   public static void main(String args[]) {
	  ThreadDemo thread1 = new ThreadDemo( "Thread-1");
	  ThreadDemo thread2 = new ThreadDemo( "Thread-2");
	  thread1.start();
	  thread2.start();
   }
}

輸出

Thread: Thread-1, State: New
Thread: Thread-2, State: New
Thread: main, State: Start
Thread: main, State: Start
Thread: Thread-1, State: Running
Thread: Thread-1, 4
Thread: Thread-1, 3
Thread: Thread-1, 2
Thread: Thread-2, State: Running
Thread: Thread-1, 1
Thread: Thread-1, State: Dead
Thread: Thread-2, 4
Thread: Thread-2, 3
Thread: Thread-2, 2
Thread: Thread-2, 1
Thread: Thread-2, State: Dead

示例 2

在這個例子中，我們建立了一個ThreadDemo類，它擴充套件了Thread類。我們沒有向Thread傳遞任何名稱，它將列印系統分配給執行緒的預設名稱。

package com.tutorialspoint;
class ThreadDemo extends Thread {
   ThreadDemo( ) {
      System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: New");
   }
   public void run() {
      System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Running");
      for(int i = 4; i > 0; i--) {
         System.out.println("Thread: " + Thread.currentThread().getName() + ", " + i); 
      }
      System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Dead");
   }
   public void start () {
      System.out.println("Thread: " + Thread.currentThread().getName() + ", " + "State: Start");
      super.start();
   }
}

public class TestThread {
   public static void main(String args[]) {
	  ThreadDemo thread1 = new ThreadDemo();
	  ThreadDemo thread2 = new ThreadDemo();
	  thread1.start();
	  thread2.start();
   }
}

輸出

Thread: main, State: New
Thread: main, State: New
Thread: main, State: Start
Thread: main, State: Start
Thread: Thread-0, State: Running
Thread: Thread-0, 4
Thread: Thread-0, 3
Thread: Thread-1, State: Running
Thread: Thread-0, 2
Thread: Thread-1, 4
Thread: Thread-0, 1
Thread: Thread-1, 3
Thread: Thread-0, State: Dead
Thread: Thread-1, 2
Thread: Thread-1, 1
Thread: Thread-1, State: Dead