There is no sizeof operator in java. How can I find size of an object in java? [duplicate]

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Programatically calculate memory occupied by a Java Object including objects it references

In Java, what is the best way to determine the s开发者_Python百科ize of an object?

Hi

There is no sizeof operator in java .. But how can i know the size of an object in java? Thanks

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You may serialize the object to a byte array output stream.

That won't give you the exact size of the object because it will skip the transient data, but at least will give you a good idea of how big your objects are.

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You can't. The internal representation is JVM-specific. If you want an empirical estimate for your JVM them you can try this: 1) turn on verbose garbage collector output (see JVM flags) 2) in your program invoke a full GC 3) create a lot of copies of the same object 4) invoke a full GC again 5) compare the heap size after steps 2 and 4 and divide by the number of objects

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There is no portable direct way, and the answer is different between JVMs (since the spec is silent on implementation details).

Here's an excellent article showing one approach.

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My first question would be what are you doing that requires sizeof? There are no pointers for you to manipulate, so you really have no need to know.

SO Duplicate?: In Java, what is the best way to determine the size of an object?