public void run()

Thread(Runnable threadOb,String threadName);

void start();

// 创建一个新的线程
class NewThread implements Runnable {
  Thread t;
  NewThread() {
   // 创建第二个新线程
   t = new Thread(this, "Demo Thread");
   System.out.println("Child thread: " + t);
   t.start(); // 开始线程
  }

  // 第二个线程入口
  public void run() {
   try {
     for(int i = 5; i > 0; i--) {
      System.out.println("Child Thread: " + i);
      // 暂停线程
      Thread.sleep(50);
     }
   } catch (InterruptedException e) {
     System.out.println("Child interrupted.");
   }
   System.out.println("Exiting child thread.");
  }
}

public class ThreadDemo {
  public static void main(String args[]) {
   new NewThread(); // 创建一个新线程
   try {
     for(int i = 5; i > 0; i--) {
      System.out.println("Main Thread: " + i);
      Thread.sleep(100);
     }
   } catch (InterruptedException e) {
     System.out.println("Main thread interrupted.");
   }
   System.out.println("Main thread exiting.");
  }
}

Child thread: Thread[Demo Thread,5,main]
Main Thread: 5
Child Thread: 5
Child Thread: 4
Main Thread: 4
Child Thread: 3
Child Thread: 2
Main Thread: 3
Child Thread: 1
Exiting child thread.
Main Thread: 2
Main Thread: 1
Main thread exiting.