Java知多少（59）创建多线程

到目前为止，我们仅用到两个线程：主线程和一个子线程。然而，你的程序可以创建所需的更多线程。例如，下面的程序创建了三个子线程：

 // Create multiple threads.
 class NewThread implements Runnable {
     String name; // name of thread
     Thread t;
     NewThread(String threadname) {
         name = threadname;
         t = new Thread(this, name);
         System.out.println("New thread: " + t);
         t.start(); // Start the thread
     }

     // This is the entry point for thread.
     public void run() {
         try {
             for(int i = 5; i > 0; i--) {
                System.out.println(name + ": " + i);
                Thread.sleep(1000);
             }
         } catch (InterruptedException e) {
             System.out.println(name + "Interrupted");
         }
         System.out.println(name + " exiting.");
     }
 }

 class MultiThreadDemo {
     public static void main(String args[]) {
         new NewThread("One"); // start threads
         new NewThread("Two");
         new NewThread("Three");
         try {
             // wait for other threads to end
             Thread.sleep(10000);
         } catch (InterruptedException e) {
             System.out.println("Main thread Interrupted");
         }
         System.out.println("Main thread exiting.");
     }
 }

程序输出如下所示：

New thread: Thread[One,5,main]
New thread: Thread[Two,5,main]
New thread: Thread[Three,5,main]
One: 5
Two: 5
Three: 5
One: 4
Two: 4
Three: 4
One: 3
Three: 3
Two: 3
One: 2
Three: 2
Two: 2
One: 1
Three: 1
Two: 1
One exiting.
Two exiting.
Three exiting.
Main thread exiting.

如你所见，一旦启动，所有三个子线程共享CPU。注意main()中对sleep(10000)的调用。这使主线程沉睡十秒确保它最后结束。

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Java知多少（上）

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