Array size in Java

Question

What would be the memory size/space occupied in bits/bytes by array as follows.

final String[] objects_user1={"1","10","100","1000","10000"};

• Michael Todd: I hope this isn't for a live test or interview....
• willcodejavaforfood: Cant be for an interview since you dont need to know really
• Laurence Gonsalves: Unless you're talking about a specific JVM implementation on a specific architecture, you can really only come up with an estimate. There is nothing in the specs that say precisely how much storage anything will take in Java.
• tpv: Also you can try this.
• David Prun: I am trying to calculate the performance of a device and running the code on it. I want to create objects of different size and then retrieve them, thus calculate the throughput.

Answer 1

ROUGH ESTIMATE: 12 bytes for array header, 4x5 bytes for the pointers (8x5 if you're on a 64 bit jvm), each string has 3 ints (+3x4 bytes), and an array of chars (+12 bytes for header + length of the string x2, because it's char).

• Jay: Yeah, I wonder that too. I think if peole are going to downvote, they should at least tell you why. I'll give you an upvote to cancel it out. :-)

Answer 2

Did you try to Google it? Here is the first result of my Google search.

Answer 3

Impossible to say, since its an implementation detail of the JRE you're using.

Answer 4

You can get an approximate answer by querying available heap space before & after the memory allocation. Run it a number of times & compute the average, & it will be pretty close to the right answer. But again, the answer is only valid for the specific JVM it's run on.