2D dynamic array using ArrayList in Java

Question

I need to implement a 2D dynamic array. The number of rows is fixed, say n. But the number of columns for each row is not fixed and equivalent. For instance, the first row h

Answer 1

You can either use a array for the rows since this dimenstion is fixed:

@SuppressWarnings("unchecked")
ArrayList[] arr = new ArrayList[ fixedsize];

or use nested ArrayLists:

List> list = new ArrayList>( fixedsize );