Java 实现多线程

Question

Thread 类本身也是实现了 Runnable 接口，而 run() 方法最先是在 Runnable 接口中定义的方法。

class MyThread extends Thread {
	@Override
	public void run(){
		for (i = 0; i < 100; i++) {
        System.out.println(Thread.currentThread().getName() + " " + i);
    }
	}
}
class MyThread1 implements Runnable {
	@Override
	public void run(){
		for (i = 0; i < 100; i++) {
        System.out.println(Thread.currentThread().getName() + " " + i);
    }
	}
}
public class ThreadTest {
  public static void main(String[] args) {
    Callable<Integer> myCallable = new MyCallable();  // 创建MyCallable对象
    FutureTask<Integer> ft = new FutureTask<Integer>(myCallable); //使用FutureTask来包装MyCallable对象
    for (int i = 0; i < 100; i++) {
      System.out.println(Thread.currentThread().getName() + " " + i);
      if (i == 30) {
        Thread thread = new Thread(ft);   //FutureTask对象作为Thread对象的target创建新的线程
        thread.start();            //线程进入到就绪状态
      }
    }
    System.out.println("主线程for循环执行完毕..");
    try {
      int sum = ft.get();      //取得新创建的新线程中的call()方法返回的结果
      System.out.println("sum = " + sum);
    } catch (InterruptedException e) {
      e.printStackTrace();
    } catch (ExecutionException e) {
      e.printStackTrace();
    }
  }
}
class MyCallable implements Callable<Integer> {
  private int i = 0;
  // 与run()方法不同的是，call()方法具有返回值
  @Override
  public Integer call() {
    int sum = 0;
    for (; i < 100; i++) {
      System.out.println(Thread.currentThread().getName() + " " + i);
      sum += i;
    }
    return sum;
  }
}