1、创建一个类实现Runnable接口，并重写run方法。

public class MyThread implements Runnable{
    ArrayList<String>aaa;
    public MyThread(ArrayList<String>aaa){
        this.aaa=aaa;
    }

    @Override
    public void run() {
        for (int i=0;i<100;i++){
            aaa.add("aaa"+i);
            System.out.println(Thread.currentThread().getName()+"aaa"+i+aaa.get(i));
        }
    }
}

写一个测试方法

public class ListDemo {
    public static void main(String[] args) {
        ArrayList<String>list=new ArrayList<>();
        MyThread m1=new MyThread(list);
        MyThread m2=new MyThread(list);

        new Thread(m1).start();
        new Thread(m2).start();

    }
}

-----结果------
Thread-0aaa0aaa0
Thread-1aaa0aaa0
Thread-0aaa1aaa0
Thread-1aaa1aaa0
Thread-0aaa2aaa1
Thread-1aaa2aaa1
Thread-0aaa3aaa1
Thread-1aaa3aaa1
Thread-0aaa4aaa2
Thread-1aaa4aaa2
Thread-0aaa5aaa2
Thread-1aaa5aaa2
Thread-1aaa6aaa3
Thread-1aaa7aaa3
Thread-0aaa6aaa3
Thread-1aaa8aaa4
Thread-1aaa9aaa4
Thread-0aaa7aaa3
Thread-1aaa10aaa5
Thread-0aaa8aaa4
Thread-1aaa11aaa5
Thread-0aaa9aaa4
Thread-1aaa12aaa6
Thread-1aaa13aaa6
Thread-0aaa10aaa5
Thread-1aaa14aaa7
Thread-0aaa11aaa5
Thread-1aaa15aaa8
Thread-0aaa12aaa6
Thread-1aaa16aaa7
Thread-0aaa13aaa6
Thread-1aaa17aaa9
Thread-0aaa14aaa7
Thread-1aaa18aaa10
Thread-0aaa15aaa8
Thread-1aaa19aaa8
Thread-0aaa16aaa7
Thread-0aaa17aaa9
Thread-0aaa18aaa10
Thread-0aaa19aaa8

Process finished with exit code 0

2、创建一个类继承Thread类，并重写run方法。

public class MyThread extends Thread{
    ArrayList<String>aaa;
    public MyThread(ArrayList<String>aaa){
        this.aaa=aaa;
    }

    @Override
    public void run() {
        for (int i=0;i<20;i++){
            aaa.add("aaa"+i);
            System.out.println(Thread.currentThread().getName()+"aaa"+i+aaa.get(i));
        }
    }
}


------结果------
Thread-0aaa0null
Thread-1aaa0null
Thread-0aaa1aaa0
Thread-1aaa1aaa0
Thread-0aaa2aaa1
Thread-1aaa2aaa1
Thread-0aaa3aaa1
Thread-1aaa3aaa1
Thread-0aaa4aaa2
Thread-1aaa4aaa2
Thread-0aaa5aaa2
Thread-1aaa5aaa2
Thread-0aaa6aaa3
Thread-1aaa6aaa3
Thread-0aaa7aaa3
Thread-1aaa7aaa3
Thread-0aaa8aaa4
Thread-1aaa8aaa4
Thread-0aaa9aaa4
Thread-0aaa10aaa5
Thread-1aaa9aaa4
Thread-0aaa11aaa5
Thread-1aaa10aaa5
Thread-0aaa12aaa6
Thread-0aaa13aaa6
Thread-0aaa14aaa7
Thread-1aaa11aaa5
Thread-0aaa15aaa7
Thread-1aaa12aaa6
Thread-0aaa16aaa8
Thread-1aaa13aaa6
Thread-0aaa17aaa8
Thread-1aaa14aaa7
Thread-0aaa18aaa9
Thread-1aaa15aaa7
Thread-0aaa19aaa10
Thread-1aaa16aaa8
Thread-1aaa17aaa8
Thread-1aaa18aaa9
Thread-1aaa19aaa10

Process finished with exit code 0

3、实现Callable接口，重写call()方法，这种方式可以通过FutureTask获取任务执行的返回值。

public class CallerTask implements Callable<String> {
    public String call() throws Exception {
        return "Hello,i am running!";
    }

    public static void main(String[] args) {
        //创建异步任务
        FutureTask<String> task=new FutureTask<String>(new CallerTask());
        //启动线程
        new Thread(task).start();
        try {
            //等待执行完成，并获取返回结果
            String result=task.get();
            System.out.println(result);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
}
-----结果-----
Hello,i am running!

4、run()方法和start()方法有什么区别？

run()：封装线程执行的代码，直接调用相当于调用普通方法。
start()：启动线程，然后由JVM 调用此线程的 run() 方法。

5、通过继承 Thread 的方法和实现 Runnable 接口的方式创建多线程，哪个好？

实现Runable接口好，原因有两个：
①、避免了Java单继承的局限性
②、适合多个相同的程序代码去处理同一资源的情况，把线程、代码和数据有效的分离，更符合面向对象的设计思想。

6、两种常见的线程控制方法

sleep()：使当前正在执行的线程暂停指定的毫秒数，也就是进入休眠的状态。
需要注意的是，sleep 的时候要对异常进行处理。

try {//sleep会发生异常要显示处理
    Thread.sleep(20);//暂停20毫秒
} catch (InterruptedException e) {
    e.printStackTrace();
}

join()：等待这个线程执行完才会轮到后续线程得到cpu的执行权，使用这个也要抛出异常。

  ArrayList<String>list=new ArrayList<>();
        MyThread m1=new MyThread(list);
        MyThread m2=new MyThread(list);
        m1.start();
        try {
            m1.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        m2.start();

结果：等待m1执行完才会轮到m2

Thread-0aaa0aaa0
Thread-0aaa1aaa1
Thread-0aaa2aaa2
Thread-0aaa3aaa3
Thread-0aaa4aaa4
Thread-0aaa5aaa5
Thread-0aaa6aaa6
Thread-0aaa7aaa7
Thread-0aaa8aaa8
Thread-0aaa9aaa9
Thread-0aaa10aaa10
Thread-0aaa11aaa11
Thread-0aaa12aaa12
Thread-0aaa13aaa13
Thread-0aaa14aaa14
Thread-0aaa15aaa15
Thread-0aaa16aaa16
Thread-0aaa17aaa17
Thread-0aaa18aaa18
Thread-0aaa19aaa19
Thread-1aaa0aaa0
Thread-1aaa1aaa1
Thread-1aaa2aaa2
Thread-1aaa3aaa3
Thread-1aaa4aaa4
Thread-1aaa5aaa5
Thread-1aaa6aaa6
Thread-1aaa7aaa7
Thread-1aaa8aaa8
Thread-1aaa9aaa9
Thread-1aaa10aaa10
Thread-1aaa11aaa11
Thread-1aaa12aaa12
Thread-1aaa13aaa13
Thread-1aaa14aaa14
Thread-1aaa15aaa15
Thread-1aaa16aaa16
Thread-1aaa17aaa17
Thread-1aaa18aaa18
Thread-1aaa19aaa19