blocks|key|614192|text|监视器只是对象的一个术语，它的方法可以在多线程环境中安全地使用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|614193|维基百科上有一篇关于监视器的很棒的文章：|614194|http://en.wikipedia.org/wiki/Monitor_(synchronization)|offset|length|614195|如果你向下滚动，它甚至还有一个section+explicitly+about+Java。|614196|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Monitor_%2528synchronization%2529|1|http://en.wikipedia.org/wiki/Monitor_%2528synchronization%2529#Implicit_condition_variable_monitors^0|0|0|0|1I|0|0|F|T|1|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@$F|W|G|X|1|Y]]|A|$]]|$1|H|3|I|5|6|7|Z|8|@]|9|@$F|10|G|11|1|12]]|A|$]]|$1|J|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q]]|R|$5|M|N|O|A|$P|S]]]]

A monitor is simply a term for an object whose methods can be safely used in a multithreaded environment.

There's a great Wikipedia article on Monitors:

<a href="http://en.wikipedia.org/wiki/Monitor_%28synchronization%29">http://en.wikipedia.org/wiki/Monitor_(synchronization)</a>

If you scroll down, it's even got a <a href="http://en.wikipedia.org/wiki/Monitor_%28synchronization%29#Implicit_condition_variable_monitors">section explicitly about Java</a>.

blocks|key|614224|text|object周围的synchronized块是它的监视器，它控制对象上的锁。下面是一个示例|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|614225|synchronized+(object)+{
+++while+(<condition+does+not+hold>)
++++++object.wait(timeout);
+++...+//+Perform+action+appropriate+to+condition
}|code-block|syntax|javascript|614226|entityMap^0|0|6|9|C|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

A <code>synchronized</code> block around an <code>object</code> is its monitor, which controls a lock on the object. Here an example

<pre><code>synchronized (object) {
 while (&lt;condition does not hold&gt;)
 object.wait(timeout);
 ... // Perform action appropriate to condition
}
</code></pre>

blocks|key|614296|text|Java虚拟机使用监视器来支持多线程。监视器通过两个概念来实现这一点-运行线程时的互斥(这里是“锁定”出现的地方)和作为线程间通信的一种方式的协调(这里是对象的等待和通知方法出现的地方)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|614297|阅读“JVM内幕”中的以下部分将会消除这个疑问，它在这里解释得很好吗(第20章，线程同步)-|614298|https://www.artima.com/insidejvm/ed2/threadsynchP.html|offset|length|614299|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|1I|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@$F|R|G|S|1|T]]|A|$]]|$1|H|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|E]]]]

The Java Virtual Machine uses monitors to support multithreading. Monitors achieve this through two concepts - Mutual exclusion while running the threads (here is where 'locking' comes into picture) and coordination as a means of inter thread communication (here is where object's wait and notify methods come into picture).

Reading the following part from "Inside JVM" will clear this doubt, is it very nicely explained over here (Chapter 20, Thread synchronization) - 

<a href="https://www.artima.com/insidejvm/ed2/threadsynchP.html" rel="nofollow">https://www.artima.com/insidejvm/ed2/threadsynchP.html</a>

blocks|key|614361|text|尽管回答这个问题为时已晚，我还是想补充一下--以防万一。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|614362|下面是一个非同步Java方法中的同步Java代码块|614363|public+void+add(int+value){
synchronized(this){
++++++this.count+%2B=+value;
+++}
}|code-block|syntax|javascript|614364|在示例中使用了"this“，这是调用add方法的实例。同步实例方法使用它所属的对象作为监视器对象。|614365|在同一监视器对象上同步的=>代码块中，只有一个线程可以执行。|614366|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Even though it is late to answer this question, I thought to just add in-case it is useful. 
Here is a synchronized block of Java code inside an unsynchronized Java method

<pre><code>public void add(int value){
synchronized(this){
 this.count += value;
 }
}
</code></pre>

In the example "this" is used, which is the instance the add method is called on.
A synchronized instance method uses the object it belongs to as monitor object.
 => Only one thread can execute inside a Java code block synchronized on the same monitor object.

When reading articles about Java threads, I often notice the expression: "current thread is the owner of this object's monitor". I get the meaning: the thread gets the right to operate on the object. But I am puzzled why we use the phrase "the object's monitor" instead of "the object's lock"?

In brief, I don't know the meaning of the word 'monitor'
The question may be strange and simple. But I wish anybody can help to solve it. 3ks

What's the meaning of an object's monitor in Java? Why use this word?

虚拟机

Java

在阅读有关Java线程的文章时，我经常注意到这样一句话：“当前线程是此对象监视器的所有者”。我明白了:线程获得了对对象进行操作的权限。但我不明白为什么我们用“对象的监视器”而不是“对象的锁”？简而言之，我不知道“显示器”这个词的意思。这个问题可能很奇怪，也很简单。但我希望任何人都能帮助解决这个问题。3ks

问在Java中，对象的监视器是什么意思？为什么要用这个词呢？
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