1.多线程的四种实现方式

1）继承Thread类

public static void main(String[] args) {
    MyThread myThread1 = new MyThread();
    MyThread myThread2 = new MyThread();
    myThread1.start();
    myThread2.start();
}
class MyThread extends Thread {
public void run() {
    System.out.println("MyThread.run()");
    }
}

2）实现Runnable接口

new Thread(new Runnable() {         
        @Override
        public void run() {
            while(true){
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    
                    e.printStackTrace();
                }
                output.output("zhangxiaoxiang");
            }
            
        }
    }).start();

3）实现Callable接口

public static void main(String[] args){
    ExecutorService executorService=Executors.newFixedThreadPool(3);
    try{
        Future<String> future=executorService.submit(new MyCallable());
        System.out.println(future.get());
    }catch(Exception e){
        System.out.println(e.getMessage());
    }
   }

class MyCallable implements Callable<String>{

@Override
public String call() throws Exception {
    Thread.sleep(5000);
    return "hello";
   }    
}

4）通过FutureTask包装器

 public static void main(String[] args) {  //         //创建线程池  
//  ExecutorService es = Executors.newSingleThreadExecutor();  
//        //创建Callable对象任务  
//        CallableDemo calTask=new CallableDemo();  
//        //提交任务并获取执行结果  
//        Future<Integer> future =es.submit(calTask);  
//        //关闭线程池  
//        es.shutdown();  
          
        //创建线程池  
        ExecutorService es = Executors.newSingleThreadExecutor();  
        //创建Callable对象任务  
        CallableDemo calTask=new CallableDemo();  
        //创建FutureTask  
        FutureTask<Integer> futureTask=new FutureTask<>(calTask);  
        //执行任务  
        es.submit(futureTask);  
        //关闭线程池  
        es.shutdown();  
        try {  
            Thread.sleep(2000);  
        System.out.println("主线程在执行其他任务");  
          
        if(futureTask.get()!=null){  
            //输出获取到的结果  
            System.out.println("futureTask.get()-->"+futureTask.get());  
        }else{  
            //输出获取到的结果  
            System.out.println("futureTask.get()未获取到结果");  
        }  
          
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
        System.out.println("主线程在执行完成");  
    }  
}