同步(synchronized)方法和同步块代码示例

同步方法

public class SafeBuyTicket {
    public static void main(String[] args) {
        BuyTicket station = new BuyTicket();
        new Thread(station,"Tenton").start();
        new Thread(station,"East").start();
        new Thread(station,"黄牛党").start();
    }
}
class BuyTicket implements Runnable{
    //票数
    private int ticket = 10;
    //外部停止方式
    boolean flag = true;
    @Override
    public void run() {
        //买票
        while (flag){
            try {
                buy();
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    private synchronized void buy() {
        //判断是否有票
        if (ticket <= 0){
            flag = false;
            return;
        }
        System.out.println(Thread.currentThread().getName() + "拿到了第" + ticket-- +"张票");
    }
}

同步块

public class SafeList {
    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        for (int i = 0; i < 10000; i++) {
            new Thread(()->{
                //锁的对象就是变化的量，需要执行增删改的对象
                synchronized (list){
                    list.add(Thread.currentThread().getName());
                }
            }).start();
        }
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(list.size());
    }
}