Is the 4 bytes of an array of type int distributed among the elements of the array in java?

Question

I want to know if the datatype of an array is the datatype of each element or the whole array. For instance, will this code reserve 4 bytes or 16 bytes of RAM?

int[] collection = {30, 40, 50, 60};

score 2 · Accepted Answer · edited May 23 '17 at 11:51

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Each of the 4 int values use 4 bytes.

However the array uses a object header which is 8 - 12 bytes long in the OpenJDK (and like JVMS)

The object alignment is 8 bytes by default so the size of the object will be rounded up to a multiple of 8.

This means the object could be 24 to 32 bytes long.

The reference to this object will be 4 bytes unless you have a 64-bit JVM which has Compressed Oops disabled.

What is in java object header

Document -XX:ObjectAlignmentInBytes

Compressed OOPs

edited May 23 '17 at 11:51

Community

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answered Sep 12 '15 at 17:47

Peter Lawrey

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I added a link to a presentation – ACV Sep 12 '15 at 17:49

score 1 · Answer 2 · answered Sep 12 '15 at 17:01

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This is an array of four elements, where each one is an int. Since a single int takes 4 bytes, the array will take a total of 4*4 = 16 bytes.

answered Sep 12 '15 at 17:01

Mureinik

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Also, 32 or 64 bits for the array reference?? – Codebender Sep 12 '15 at 17:03

Is the 4 bytes of an array of type int distributed among the elements of the array in java?

2 Answers2