I came across a code like this

synchronized(obj) {

obj = new Object();

}

Something does not feel right about this , I am unable to explain, Is this piece of code OK or there is something really wrong in it, please point it out.

Thanks

解決方案

It's probably not what you want to do. You're synchronizing on an object that you're no longer holding a reference to. Consider another thread running this method: they may enter and try to hit the lock at the moment after the reference to obj has been updated to point to the new object. At that point, they're synchronizing on a different object than the first thread. This is probably not what you're expecting.

Unless you have a good reason not to, you probably want to synchronize on a final Object (for visibility's sake.) In this case, you would probably want to use a separate lock variable. For example:

class Foo

{

private final Object lock = new Object();

private Object obj;

public void method()

{

synchronized(lock)

{

obj = new Object();

}

}

}

總結(jié)

以上是生活随笔為你收集整理的java 同步 变量,在java中的对象上同步，然后更改同步的变量的值的全部?jī)?nèi)容，希望文章能夠幫你解決所遇到的問(wèn)題。

如果覺(jué)得生活随笔網(wǎng)站內(nèi)容還不錯(cuò)，歡迎將生活随笔推薦給好友。