How to calculate memory usage of an object?

I'm implementing a caching system for android app, I need to add a parameter that specify the maximun amoun开发者_JAVA技巧t of memory permited for caching, but I don't know how to calculate the memory used for an object.

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Apparently 1.5 added an instrumentation interface. Check out this article

http://www.javapractices.com/topic/TopicAction.do?Id=83

you can use a getObjectSize() method. Its implementation specific and an approximation but better than nothing

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You can consider getting a heap dump of the application and observing its Retained Heap

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It depends on the object. Calculate how much memory each part of the object takes when allocated to get a baseline for the max size the object can be.