Collision detection : rounded object

Question

I\'m developing a Java game (but the dev. language doesn\'t really matter) including rounded objects like balls or pucks, and now working on collisions. I use a timer, so o

Answer 1

An addition to @Ankit's solution:

boolean areColliding(Circle c1, Circle c2){

    center_distance = (x1-x2)^2 +(y1-y2)^2;  //this is the distance between the centers of the two circles.

    if((c1.r+c2.r)^2 < center_distance)
        return false;
    else
        return true;
}

This just compares the squared distances. Result is the same, but no square root and huge performance benefit.