關於IllegalMonitorStateException異常-線程安全

也就是當前的線程不是此對象監視器的全部者。當前線程要鎖定該對象以後，才能用鎖定的對象執行這些方法，這裏須要用到synchronized關鍵字，鎖定哪一個對象就用哪一個對象來執行notify(), notifyAll(),wait(), wait(long), wait(long, int)操做，不然就會報IllegalMonitorStateException異常。

1.鎖定方法的所屬的實例對象

public synchronized void method（）{
    //而後就能夠調用：this.notify()...
    //或者直接調用notify()...
}

 2.鎖定方法所屬的實例的class

public Class Test{
 public static synchronized void method（）{
    //而後調用：Test.class.notify()...
 }
}

3.鎖定其餘對象：

public Class Test{
public Object lock = new Object();
 public static void method（）{
    synchronized (lock) {
     //須要調用 lock.notify();
    } 
 }
}

測試：

private Person person = new Person();

    public void addProduct(){
        synchronized (person){
            try {
                //wait();//IllegalMonitorStateException
                //person.wait();//正常
                Clerk.class.wait();//IllegalMonitorStateException
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

 

測試2：
public class Clerk {

    //當前商品數量
    private int product = 0;

    private static Person person = new Person();

    public static synchronized void addProduct(){
        try {
            //wait();//編譯報錯
            // person.wait();//IllegalMonitorStateException
            //Person.class.wait();//IllegalMonitorStateException
            Clerk.class.wait();//正常
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}