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

List> twoDList = new ArrayList>(n);
for( int i=0; i() );

Use as:

twoDList.get(rownumber).add(newElementInColumn);