Java创建线程的方式

Java创建线程的方式

方式一: 继承Thread类,重写run()方法

public class Test_Thread {
    public static void main(String[] args) {
        new Thread_Demo().start();
        new Thread_Demo().start();
        new Thread_Demo().start();
    }
}

/**
 * 创建线程的方式一:
 * 继承 Thread 类，并重写 run() 方法
 */
class Thread_Demo extends Thread{
    @Override
    public void run() {
        for(int i = 0;i<5;i++){
            System.out.println(Thread.currentThread().getName() + ", i = " + i);
        }
    }
}

方式二: 实现Runnable接口

import java.util.concurrent.TimeUnit;

public class Test_Runnable {

    public static void main(String[] args) {
        // 写法一,new一个Runnable的实现类对象作为构造入参
        new Thread(new Runnable_Demo()).start();
        new Thread(new Runnable_Demo()).start();
        new Thread(new Runnable_Demo()).start();

        try {
            // 休眠1秒
            TimeUnit.SECONDS.sleep(1);

            // 写法二, 函数式编程
            new Thread(()->{
                for(int i = 0;i<5;i++){
                    System.out.println(Thread.currentThread().getName() + ", i = " + i);
                }
            }).start();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

/**
 * 方式二：实现接口Runnable
 * 作为Thread的构造入参来启动
 */
class Runnable_Demo implements Runnable{
    @Override
    public void run() {
        for(int i = 0;i<5;i++){
            System.out.println(Thread.currentThread().getName() + ", i = " + i);
        }
    }
}

方式三: Callable与Future结合

在方式一与方式二中都无法直接获得线程的返回结果，只能通过共享变量等方法；使用Callable和Future方法可以获取到线程的执行结果。

import java.util.Random;
import java.util.concurrent.*;

public class Test_Callable {

    public static void main(String[] args) throws ExecutionException, InterruptedException {

        // 普通写法
        ExecutorService executorService = Executors.newFixedThreadPool(1);
        Future<Integer> submit = executorService.submit(new Callable_Demo());
        Integer result = submit.get();
        System.out.println("result is " + result);

        // 函数式编程
        Integer futureRes = executorService.submit(()->{
            int res = new Random().nextInt();
            System.out.println("Random is " + res + ", call method2 is running... ");
            return res;
        }).get();
        System.out.println("futureRes is " + futureRes);
        
        // 关闭服务
        executorService.shutdown();
        // 关闭服务后不能再新增线程到线程池中，下面代码在运行中会报错
        executorService.submit(()->{
            System.out.println("1245");
        });
        
    }

}

/**
 * 方式三 实现Callable接口,可以获取线程的执行结果
 * 需要结合Future和Executor*来实现
 */
class Callable_Demo implements Callable<Integer> {

    @Override
    public Integer call() throws Exception {
        int result = new Random().nextInt();
        System.out.println("Random is " + result + ", call method is running... ");
        return result;
    }
}