I'm trying to write a tetris clone. My board is a 10x20 array of integers on which 0 means no tile, 1-7 means a tile of specific color. It is constantly translated to graphic interpretation. My shapes are 4x4 arrays of integers. I've just come to a realisation that while making all of the shapes 4x4 makes some things easier, it also causes a problem when moving a piece left and right. Let's say we've got the I shape:
0010
0010
0010
0010
Now, if I move it to left wall there will always be a two units long gap, since the 0s cant move outside of the main board array. What would be the easiest way to allow the 1s to move to the left wall without causing an out of bounds exception?
Using your described method, one way to simply avoid getting the IndexOutOfBoundsException would be to expand your board to be 18 x 24 instead of 10 x 24, and then write in additional code that doesn't let you move a block left/right if there would be any 1's in the object array that leave the middle 10 squares of the grid. By adding this 'padding' to your grid, you avoid the exception and should still be able to implement.
I hope this approach makes sense to you. If not I can provide a more pseudo-code driven answer, but I hope you get the idea. (Just comment if you have any questions.)
BTW, @assylias makes a very good point. It is important to have a good design/plan before you start implementing things to avoid road-bumps like these. It comes with experience, so keep practicing and you will get the hang of it.
NOTE: As Nick pointed out in the comment, another way of doing this is to simply check if any 1's leave the grid before moving any of the arrays. This is certainly possible (and arguably a more elegant/simple solution), although it may be a bit harder to get right.