Use Java multi-threaded There are three ways summary

Use Java multi-threaded There are three ways Summary:

Thread class inheritance

Implement Runnable

And create threads using Callable and Future

This article will introduce one by one these three methods.

1, inheritance Thread class

---

public class MyThread extends Thread {
    @Override
    public void run(){
        super.run();
        System.out.println("执行子线程...");
    }
}

public class Test {
    public static void main(String[] args) {
        MyThread myThread = new MyThread();
        myThread.start();
        System.out.println("主线程...");
    }
}

2, implement Runnable

---

public class MyRunnable implements Runnable {
    @Override
    public void run() {
        System.out.println("执行子线程...");
    }
}

public class Test {
    public static void main(String[] args) {

        Runnable runnable = new MyRunnable();
        Thread thread = new Thread(runnable);
        thread.start();
        System.out.println("主线程运行结束!");
    }
}

3, using the Callable and Future create a thread

import java.util.concurrent.Callable;

public class MyCallable implements Callable {
    int i = 0;
    @Override
    public Object call() throws Exception {
        System.out.println(Thread.currentThread().getName()+"  i的值："+ i);
        return i++; //call方法可以有返回值
    }
}

import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;

public class Test {
    public static void main(String[] args) {
        Callable callable = new MyCallable();
        for (int i = 0; i < 10; i++) {
            FutureTask task = new FutureTask(callable);
            new Thread(task,"子线程"+ i).start();
            try {
                //获取子线程的返回值
                System.out.println("子线程返回值："+task.get() + "\n");
            }  catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

5 contrast, three ways

The first two and the following comparison:

1, the code can be seen, the first method is the most simple and convenient, can directly start, without any conversion
. 2, the first place is a very good due to a single inherited after the Thread class java inheritance mechanism , can not inherit from other classes, while if the implementation of the interface, you can implement multiple interfaces, allowing developers more flexibility.

The second and third way comparison:

1, Similarly, the third embodiment is the second method is relatively simple code more, more convenient, less time converter
2, the third method has two advantages: the return value wait for the results can be thrown

to sum up:

First and second, they are to run method overrides or implements, and are thread asynchronous

A third implementation call method, and the sub-synchronous asynchronous thread main thread wait for the results set

supplement

Lambda use in java1.8 can easily achieve a thread

new Thread(()-> 
       EmailUtil.sendWorkbookGropBuy(gropBuyService.creatGropBuy(businessId,cardId ,userId         
       ,count),user.getEmail())
).start();