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Multithreading - Creation of threads

王林

Release： 2019-08-22 16:04:27

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How to create threads

Let’s summarize how to create multi-threads. There are four ways to implement multi-threads. Next, we will talk about the creation methods in detail

1. Inherit the Thread class, and then override the run() method

2. Implement the Runnable interface, and then override the run() method

3. Implement the callable interface, and then override the call< v>Method

4. Thread pool (discussed later, because it is more complicated)

Note: No matter which method is used to create a thread, start the thread using the start provided by the Thread class. ()method.

1. Inherit the Thread class and override the run method

class MyThread extends Thread {
    private String title;
    private int ticket = 20;
 
    public MyThread(String title) {
        this.title = title;
    }
 
    public void run() {  //放每个线程的子任务
        while (ticket > 0) {
            System.out.println("当前线程为"+title+"，还剩下"+ticket--+"票");
        }
    }
}
 
public class ThreadTest {
    public static void main(String[] args) {
        MyThread myThread1 = new MyThread("黄牛A");
        MyThread myThread2 = new MyThread("黄牛B");
        MyThread myThread3 = new MyThread("黄牛C");
        myThread1.start();
        myThread2.start();
        myThread3.start();
    }
}

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2. Implement the Runnable interface and override the run method

class MyRunnable implements Runnable{
    @Override
    public void run() {
      for(int i =0;i <10;i++){
          System.out.println(Thread.currentThread().getName()+"、i="+i);
      }
    }
}
public class RunnableTest {
    public static void main(String[] args) {
       Runnable runnable =new MyRunnable();      //向上转型
        new Thread(runnable,"线程A").start();    //设置线程名字
        new Thread(runnable).start();     //没有设置线程名字，则是系统默认从 Thread-(0,1,2...)
        Thread thread1 = new Thread(runnable);
        thread1.setName("线程B");        //调用setName()设置名字
        thread1.start();
    }
}

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Here are the three ways to create thread names:

(1) Add the name directly after the brackets

(2) Call setName() to set Name

(3) If no name is set, the system defaults to Thread-(0,1,2....)

3. Implement the Callable interface and override the call method

class MyCallable implements Callable<String>{
    private int ticket =20;
    @Override
    public String call() throws Exception {
        while(ticket > 0){
            System.out.println(Thread.currentThread().getName()+"还剩下"+ticket--+"票");
        }
        return "票卖完了，再见";
    }
}
public class CallableTest {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        //产生Callable对象
        MyCallable myCallable = new MyCallable();
        //产生FutureTask对象
        FutureTask futureTask = new FutureTask(myCallable);
        Thread thread = new Thread(futureTask);
        thread.start();
        System.out.println(futureTask.get()); //接收Callable对象的返回值
    }
}

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1. First generate a Callable object

2. Generate a FutureTask object

3. Create a Thread pass Enter the FutureTask object

4. The return value received from the Callable interface is the get() method in Future

Comparison of three ways to create threads

1 .Inheriting the Thread class has the limitation of single inheritance. Relatively speaking, implementing the Runnable interface is more flexible, and the Thread class itself also implements the Runnable interface to assist the real thread class

2. Implementing the Runnable interface can better realize program sharing Concept

3. The Callable interface is used when a return value is required

If there are obvious errors in the above content, please point it out, I would be grateful. Thanks!

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