You did this in one day? This is fast for a first game 
Fullscreen works perfectly…
But it somehow looks non-smooth.
I downloaded the source,
looked at the game loop: Seems okey, checked.
let the code print the fps, compiled and started: FPS is a constant 62.
I guess your problem lies in the famous spikes.
Spikes are some frames which just accedently take much more time than they should. Then it appears like it would be slower, but it isn’t.
looks at code again
It seems like your “draw()” method in mainPong.java is “synchronized”. Remove this keyword, it propably doesn’t does what you want it to do.
One more thing:
To answer your question about random ball-launching:
Replace this:
//launch ball
if(keyCode == KeyEvent.VK_SPACE){
ball.setVelocityX(3f);
ball.setVelocityY(3f);
startMsg = false;
}
With this:
//launch ball
if(keyCode == KeyEvent.VK_SPACE){
// We create a "rand" instance for generating random stuff.
// It would be a better practice, if you store the rand
// in this class's fields.
Random rand = new Random();
// rand.nextBoolean() returns randomly either true or false
if (rand.nextBoolean() == true) {
// If it's true, then the X-Velocity is positive, else it's negative.
ball.setVelocityX(3f);
} else {
ball.setVelocityX(-3f);
}
if (rand.nextBoolean() == true) {
ball.setVelocityY(3f);
} else {
ball.setVelocityY(-3f);
}
startMsg = false;
}
I think I don’t have to explain it, as it should already be done in the comments.
