对两种多线程的对比：

// Runnable 就是一个接口，Thread类实现了Runnable，Runnable存在解决只能单继承Thread的问题。
//因为Thread也实现了Runnable接口 且Runnable接口中只存在一个Run方法
// 因此，无论是implements Runnable还是 extendsThread都要实现run方法
// 只是如果是直接继承Thread类，当我们调用多线程的时候可以直接.start()
// 如果是通过实现Runnable接口，那么需要实例化Thread类来调用.start()

// Runnable 接口更适合于多个线程处理统一资源

1、直接继承Thread类

package com.temp;

/**
 * @Author lanxiaofang
 * @email 983770299@qq.com
 * @date 2020/12/5 13:08
 */
public class P205_07_Thead{
    public static void main(String[] args) {
        TestThread testThread1 = new TestThread("1");
        TestThread testThread2 = new TestThread("2");
        testThread1.start();
        testThread2.start();
        System.out.println("main is ending");
    }
}

class TestThread extends Thread{
    private String name;
    public TestThread(String name){
        this.name = name;
    }

    @Override
    public void run() {
        for (int i  = 0;i<5;i++){
            try {
                sleep((int)(1000*Math.random()));
            } catch (InterruptedException interruptedException) {
                interruptedException.printStackTrace();
                System.out.println(interruptedException);
            }
            System.out.println(name + " is Running "+i);
        }
    }
}

2、实现Runnable接口 

package com.temp;

/**
 * @Author lanxiaofang
 * @email 983770299@qq.com
 * @date 2020/12/5 14:35
 */
public class P207_08_Runnablr {
    public static void main(String[] args) {
        TestThread2 testThread2 = new TestThread2("testThread2");
        TestThread2 testThread21 = new TestThread2("testThread21");
        Thread thread1 = new Thread(testThread2);
        Thread thread2 = new Thread(testThread21);
        thread1.start();
        thread2.start();
    }
}

class TestThread2 implements Runnable{

    private String name;
    public TestThread2(String name){
        this.name = name;
    }

    @Override
    public void run() {
        for (int i=0;i<5;i++){
            try {
                Thread.sleep((int)(1000*Math.random()));
            } catch (InterruptedException interruptedException) {
                interruptedException.printStackTrace();
                System.out.println(interruptedException);
            }
            System.out.println(name+" is running "+i);
        }
    }
}