how to declare 10^9 size array in java

Question

The following error is being shown:

"Exception in thread "main" java.lang.OutOfMemoryError: Java heap space"

when I declare:

long[] ar = new long[1000000000];

So how to declare an array which size is 10^9?

Answer 1

To create an array of one billion 8 bytes long values you need at least 8 GB of free memory in the old generation. I suggest giving the heap at least 12 GB, if you have enough memory start with 32 GB.

if you don't have this much memory, you can use a memory mapped file on Linux, but most likely there is a more memory efficient way to store the data (depending on why you are trying to do this)