How to make ArrayList that work as two dimentional array in java?

Question

I want to make arrayList object in java that work as two dimentional array. My question is how can we access value from specific dimention from arrayList.

in two diment

Answer 1

Memory is an important consideration here.

It can be acceptable to model a 2D (or higher dimension) array using a 1D container. (This is how the VARIANT SAFEARRAY of Microsoft's COM works.) But, consider this carefully if the number of elements is large; especially if the container allocates a contiguous memory block. Using something like List will model a jagged-edged matrix and can fragment your memory.

With the 1D approach, you can use the get(index) method on the ArrayList appropriately transformed:

Given the (i)th row and (j)th column, transform using index = i * rows + j where rows is the number of rows in your matrix.