Type Safety: Cast from Object to E

[AaronJM]

I've been working in Eclipse on a class that holds a collection of objects in a 2D array. To enable generic types, I make casts between Object and E when initializing my array in my constructor:

class HexArray<E> {

private E[][] grid;

public HexArray(int rowSize, int colSize) {

grid = (E[][])new Object[row][col];

...
}
...
}

The thing is I get a warning when I initialize my grid array saying "Type safety: The cast from Object[][] to E[][] is actually checking against the erased type Object[][]." It's not an error; just an Eclipse warning. Should I worry/care about this?

[evlich]

Arrays in Java are weird, there is no association between subclasses in arrays. For instance:

Object[] objs = new String[5];

is not valid. When Java implements generics they do something called "type erasure" that means they basically change all of your Es to Objects after the typing has been done. So I would guess that this warning is meaning something like: "You are casting Object[][] to Object[][], this doesn't do anything at all!" So, basically I would say that since it is just a warning you can probably safely ignore it. If you are worried about it, you can convert to something that gives a bit more type safety like Lists or Vectors or whatever.

Hope this helps.