Custom java Graphics.drawLine() equation?

[Geekygirl]

I'm writing a custom class of my own to draw lines and points the way I want to, but I'm having an issue of graphing lines. I've got an \[code\]ArrayList\[/code\] of a class I wrote extending \[code\]java.awt.Point\[/code\], and when I call the method to draw the line, I'd like to first just add them to the arraylist, to be rendered when I want them to. I have the end point, and the start point of the line, but I don't know how to get the slope, or get all the points along it either. I'd like to know how to do this, but in code.