Question

I come from a C++ background and I want to have a matrix of

ArrayList<arrayList<E>> javamatrix 

In C++ I would just do

std::vector<std::vector<T> > cppmatrix;
std::vector<T>vcol(cols);
cppmatrix.resize(rows,vcol);

I can’t seem to find a built-in resize() function for ArrayLists for this task, so should I use another collection? Is no way to do this except using for loops with javamatrix.add()?

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P.S I want it to be initialized in the constructor with its size as that size might be queried before I edit elements or add or remove.

Answer 1

There is no resize equivalent that automatically constructs and adds elements. You must do this yourself. However, ensureCapacity is equivalent to vector’s reserve. It will ensure you have room, but not change the actual size.