In the question by DKSRathore How to simulate the Out Of memory : Requested array size exceeds VM limit some odd behavior was noted when creating an arrays.

When creating an array of size Integer.MAX_VALUE an exception with the error java.lang.OutOfMemoryError Requested array size exceeds VM limit was thrown.

However when an array was created with a size less than the max but still above the virtual machine memory limit the error message read java.lang.OutOfMemoryError: Java heap space.

Testing further I managed to narrow down where the error messages changes.

long[] l = new long[2147483645]; exceptions message reads - Requested array size exceeds VM limit

long[] l = new long[2147483644]; exceptions message reads - Java heap space errors

I increased my virtual machine memory and still produced the same result.

Has anyone any idea why this happens?

Some extra info: Integer.MAX_VALUE = 2147483647.

Edit: Here's the code I used to find the value, might be helpful.

int max = Integer.MAX_VALUE;
boolean done = false;
while (!done) {
    try {
        max--;
        // Throws an error
        long[] l = new long[max];
        // Exit if an error is no longer thrown
        done = true;
    } catch (OutOfMemoryError e) {
        if (!e.getMessage().contains("Requested array size exceeds VM limit")) {
            System.out.println("Message changes at " + max);
            done = true;
        }
    }
}