The Other Walls

At this point, depending on the speeds you picked for your ball initially, it is either falling off the bottom or going through the left wall. What you should do now is add an if statement to make the ball bounce off whatever wall it currently disappears through. Then, run your applet again, see where it disappears next and fix then add an if statement for that wall. In that way, you will add one if statement at a time until you have one for each wall. They will all be similar, but:

• The condition to check will depend on the wall. For the right wall, you checked to see if the x coordinate was greater than 200. For the bottom you will need to see if the y coordinate is greater than 200. For the top and left walls you will need to see if the appropriate coordinate is less than 1.

• The assignment statement placed within the if statement for the right wall reversed the direction of horizontal motion. You want to do exactly the same thing for the left wall. For the top and bottom you want to reverse the direction of vertical motion by negating the yspeed variable.

When all the if statements are in place, the ball should bounce from wall to wall until you select quit from the file menu.