Java基础之多线程的三种实现方式

class MyThread extends Thread{
    public void run(){
        System.out.println("My Thread.run()");
    }
}

MyThread myThread1 = new MyThread();
myThread1.start();

@FunctionalInterface    // 从JDK1.8引入了Lambda 表达式之后就变为了函数式接口
public interface Runnable {
  public void run();
}

public class MyThread extends OtherClass implements Runnable {
　　public void run() {
　　 System.out.println("MyThread.run()");
　　}
}

MyThread myThread = new MyThread();
Thread thread = new Thread(myThread);
thread.start();

public void run() {
　　if (target != null) {
　　 target.run();
　　}
}

 public class Thread extends Object implements Runnable{}

Thread类也是Runnable 接口的子类，那么在之前继承Thread类的时候实际上覆写的还是Runnable的方法。

@FunctionalInterface
public interface Callable<V> {
 public V call() throws Exception;
}

import java.util.concurrent.*;
import java.util.Date;
import java.util.List;
import java.util.ArrayList;
 
/**
* 有返回值的线程
*/
@SuppressWarnings("unchecked")
public class Test {
	public static void main(String[] args) throws ExecutionException,
	   InterruptedException {
	   System.out.println("----程序开始运行----");
	   Date date1 = new Date();
	 
	   int taskSize = 5;
	   // 创建一个线程池
	   ExecutorService pool = Executors.newFixedThreadPool(taskSize);
	   // 创建多个有返回值的任务
	   List<Future> list = new ArrayList<Future>();
	   for (int i = 0; i < taskSize; i++) {
	    Callable c = new MyCallable(i + " ");
	    // 执行任务并获取Future对象
	    Future f = pool.submit(c);
	    // System.out.println(">>>" + f.get().toString());
	    list.add(f);
	   }
	   // 关闭线程池
	   pool.shutdown();
	 
	   // 获取所有并发任务的运行结果
	   for (Future f : list) {
	    // 从Future对象上获取任务的返回值，并输出到控制台
	    System.out.println(">>>" + f.get().toString());
	   }
	 
	   Date date2 = new Date();
	   System.out.println("----程序结束运行----，程序运行时间【"
	     + (date2.getTime() - date1.getTime()) + "毫秒】");
	}
}
 
class MyCallable implements Callable<Object> {
	private String taskNum;
	 
	MyCallable(String taskNum) {
	   this.taskNum = taskNum;
	}
	 
	public Object call() throws Exception {
	   System.out.println(">>>" + taskNum + "任务启动");
	   Date dateTmp1 = new Date();
	   Thread.sleep(1000);
	   Date dateTmp2 = new Date();
	   long time = dateTmp2.getTime() - dateTmp1.getTime();
	   System.out.println(">>>" + taskNum + "任务终止");
	   return taskNum + "任务返回运行结果,当前任务时间【" + time + "毫秒】";
	}
}