如何在类和jvm中获取活动对象？

Question

hello all my question is if we have 10 object of class and three of them passed to garbage collector. now we have seven active object. how can we get number of active object in class and in jvm.

Answer 1

您可以在类中使用static计数器，并在构造函数中对其进行递增，并在终结器中对其进行递减，但是我不确定您为什么在乎。

Answer 2

You can not assume something like that if you do object= null there is no guarantee that JVM will do garbage collection. But since you don't have reference now you will not able to access it.

In java you don't have to care about memory till your program exits with OutOfMemoryException but standard programming practices still apply :)

You can read more about The Reachability Lifecycle of Objects

You can use profiler to see active object count eg JProfiler

As a solution you can use Object Pool Pattern But it is a anti-pattern