线程基础

java开发经常会问到是不是线程安全的？什么叫线程安全呢，就是多个线程访问这个类的时候，这个类仍然能返回正确的结果.

请看下面的demo

public class MyThread extends Thread{

private int count =5;


@Override
public synchronized void run() {//这里加上关键词synchronize,才能保证这个方法是上锁的,这样就能保证一个线程访问的时候，其他线程不能访问.
count--;
System.out.println(this.currentThread().getName()+" count="+count);
}

public static void main(String[] args) {
MyThread myThread = new MyThread();
Thread t1 = new Thread(myThread,"t1");
Thread t2 = new Thread(myThread,"t2");
Thread t3 = new Thread(myThread,"t2");
Thread t4 = new Thread(myThread,"t2");
Thread t5 = new Thread(myThread,"t2");
t1.start();
t2.start();
t3.start();
t4.start();
t5.start();
}

}