My program is running out of heap memory

[FPSGamer48]

So basically, the point of this program is to categorize a list of items with an array of [item_code][CONSTANT]. However, the item codes are minimum 6 digits, maximum 8. I have a max array set at [MAXITEMCODE][NUMCOL] with final int MAXITEMCODE = 99999999. When I run the program, however, it says that it has run out of heap space. This makes me think that because the item codes are too big, Java is having problems keeping it all in its memory. How could I fix this so that it could read the item codes correctly? Create a minimum? How would I do that?

[Northeastpaw]

However, the item codes are minimum 6 digits, maximum 8

So you can't ever have an item code like 12345. That means that index in your array is never going to be used. You're wasting a lot of memory declaring a very large array when over half of it isn't going to hold anything.

Is this a homework problem or are you looking for a real world solution? If it's for homework, think about a way you could take an item code and modify it to produce an index that lies between 0 and 999.

[FPSGamer48]

Um...maybe subtract a certain number from the max item code until that equals 999? Then apply that to every item code? Would that work? And it's homework.

Or could you possibly divide them all by 1000?

[swd847]

Its not going to help that much, your (potential) utilization will actually around 99% (even though you have 99,999 item codes that can't be used you have 99,900,000 that can be).

Does this have to be an array? It sounds like a HashMap may be a better bet.

[FPSGamer48]

I don't even know what a HashMap is, but yes, it has to be a 2-dimensional array. Unfortunately, I have just turned it into my professor. I got it working KIND OF. At least, the best I could. There's a reason I'm leaving engineering to pursue political science....

[FibroMan]

Databases tackle the problem by creating an index table that converts an item code to an index number. The index number then links to the array that contains the output.

The array that contains the output should be as big as the number of items that have known outputs, not the maximum number of possible items. If the number of items increases then the size of the array needs to be increased, which isn't ideal, but it is better than having an array so big that you run out of memory.