一： 两种实现方式：

1.继承Thread类重写run方法
2.继承Runnable接口重写run方法(通常用这种，java单继承的局限性，后期还想继承其他类会无从下手)

二：简单demo1（多线程模拟买票）

package 多线程;

public class BuyTicket {
    public static void main(String[] args) {
        TickThread tt = new TickThread();
        Thread t1 = new Thread(tt,"张三");
        Thread t2 = new Thread(tt,"李四");
        Thread t3 = new Thread(tt,"王五");
        t1.start();
        t2.start();
        t3.start();
    }
}
class TickThread implements Runnable{
    private  int total = 10;
    @Override
    public void run() {
        while (total>=1) {
            total--;
            System.out.println(Thread.currentThread().getName() + "买了票，剩余" + total + "张");
        }
        System.out.println(Thread.currentThread().getName()+"发现售罄");
    }
}

由于资源没有加锁，导致数据异常问题

三 简单demo2（模拟龟兔赛跑）

package 多线程;

public class RunGame {
    public static void main(String[] args) {
        Runner rn = new Runner();
        Thread rabbit = new Thread(rn,"rabbit");
        Thread tortoise = new Thread(rn,"tortoise");
        rabbit.start();
        tortoise.start();

    }
}
class Runner implements Runnable{
    private int stage = 100;
    private String winner=null;
    @Override
    public void run() {
       for(int i=1;i<=100;i++){
           if(isOver(i)==true) {
               Thread.currentThread().interrupt();
               break;
           }

       }

    }
    boolean isOver(int step){
        if (winner!=null){
            return true;
        }else{
            if(step==100){
                System.out.println(Thread.currentThread().getName()+"胜利！");
                winner=Thread.currentThread().getName();
                return true;
            }else{
                System.out.println(Thread.currentThread().getName()+"->"+step);
                return false;
            }
        }
    }
}