I've made a tile engine that has 30px by 30px. I've ran into a problem with an object for example.

I've loaded an object 20px by 20px and when I do a collision check I have to use x/y position which is top left in Java2D. How can I do collision detection based on the entire object?

This is relevant code:

boolean checkCol() {
    int currentGridX = ship.getX()/30;
    int currentGridY = ship.getY()/30;

    if(test[currentGridX][currentGridY] == 0)
        return true;

    System.out.println("collision");
    return false;
}