关于IllegalMonitorStateException异常产生的原因

秒速五厘米 2022-01-10 06:51 233阅读 0赞

先查看源码：

/**
     * Thrown to indicate that a thread has attempted to wait on an
     * object's monitor or to notify other threads waiting on an object's
     * monitor without owning the specified monitor.
     *  抛出该异常表明某一线程已经试图等待对象的监视器，或者试图通知其他正在等待对象的监视器，然而本身没有指定的监视器的线程。
     * 
     * @author  unascribed
     * @see     java.lang.Object#notify()
     * @see     java.lang.Object#notifyAll()
     * @see     java.lang.Object#wait()
     * @see     java.lang.Object#wait(long)
     * @see     java.lang.Object#wait(long, int)
     * @since   JDK1.0
     */
     public
    class IllegalMonitorStateException extends RuntimeException {
        private static final long serialVersionUID = 3713306369498869069L;
    
        /**
         * Constructs an <code>IllegalMonitorStateException</code> with no
         * detail message.
         */
        public IllegalMonitorStateException() {
            super();
        }
    
        /**
         * Constructs an <code>IllegalMonitorStateException</code> with the
         * specified detail message.
         *
         * @param   s   the detail message.
         */
        public IllegalMonitorStateException(String s) {
            super(s);
        }
    }

当前的线程不是此对象监视器的所有者。当前线程要锁定该对象之后，才能用**锁定的对象**执行这些方法，这里需要用到synchronized关键字，锁定哪个对象就用哪个对象来执行notify(), notifyAll(),wait(), wait(long), wait(long, int)操作，否则就会报IllegalMonitorStateException异常

public void waitKm(){
     		try {
     				//这里synchronized锁的那个对象就用那个对象调用wait()方法，其他方法同理
                    synchronized (obj) {
                        obj.wait();
                    }
             } catch (InterruptedException e) {
                    e.printStackTrace();
            }
     }