Java – 线程命名及示例

在实现 Runnable 接口时命名线程

如果您的类旨在作为线程执行并实现Runnable接口，则需要使用以下构造函数实例化Thread对象：

Thread(Runnable threadObj, String threadName);

其中，threadObj是实现Runnable接口的类的实例，threadName是赋予新线程的名称。

创建 Thread 对象后，您可以通过调用start()方法启动它，该方法会调用run()方法。以下是start()方法的简单语法：

void start();

示例

在这个例子中，我们通过实现Runnable接口创建一个RunnableDemo类。RunnableDemo类具有run()方法的实现。在主类TestThread中，我们创建了RunnableDemo对象，并使用这些对象创建了两个Thread对象。当在每个线程对象上调用Thread.start()方法时，线程开始处理，程序开始执行。

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();
   }
}

输出

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

扩展 Thread 类时命名线程

创建线程的第二种方法是创建一个扩展Thread类的新的类。这种方法在处理使用Thread类中可用方法创建的多个线程时提供了更大的灵活性。为了命名线程，我们需要使用名称调用超类Thread构造函数。

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

示例 1

以下是重写为扩展Thread的前面程序：在这个例子中，我们创建了一个ThreadDemo类，它扩展了Thread类。我们在constructor()方法中调用super(name)来为线程分配名称，并调用super.start()来启动线程处理。

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();
   }
}

输出

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

在这个例子中，我们创建了一个ThreadDemo类，它扩展了Thread类。我们没有向Thread传递任何名称，它将打印系统分配给线程的默认名称。

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();
   }
}

输出

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