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Making the Paddle Useful

To make the paddle important to the game, you have to make it possible for the ball to fall off the bottom again. At this point, your "animate" method should contain an if statement that looks something like:

if ( y > 200) {
      yspeed = -1*yspeed;
}

You don't want to delete this statement. You still need to do something important when the ball reaches the bottom of the screen display. The trick is that what you want to do is itself "conditional". If the paddle is in the right place, you want the ball to bounce. Otherwise, you want to make the ball disappear until the user clicks the mouse to get a fresh ball.

This means that you need to replace the assignment

      yspeed = -1*yspeed'

with another if statement which will depend on the position of the paddle. You will have one if statement (the one about the paddle) contained within another (the one about the ball reaching the bottom of the screen).

The condition of the inner if statement is also a bit complicated. The ball hits the paddle only if it's x coordinate is greater than that of the left edge of the paddle and less then that of the right edge. In Java, conditions involving one condition and another are written by joining the two simple conditions by a double ampersand (&&). So, the if statement you need to write will look like:

if ( first-condition && second-condition ) {
      make the ball bounce
} else {
      make the ball hide
}

You already know how to make the ball bounce. Just negate yspeed as you did before. To make the ball hide, set the y coordinate to something like 250 and the yspeed to 0. This will make the ball wiggle back and forth just below the screen waiting for the player to click.

So, replace the assignment "yspeed = -1 * yspeed" with an if statement for the appropriate conditions that reverses the ball if the condition holds and leaves it in suspended animation otherwise. Then, run your applet and see if the paddle works.