I am trying to design a java game with realistic physics?

Like the title says, I am writing a Java game and trying to include realistic trajectory physics. This sounded pretty easy to me but I think I have managed to make it way more complicated than it needs to be, and it's not working. Basically at this point, I have a guy throwing a ball, and the ball velocity and angle are based on the distance and angle from the guy that the mouse is clicked. The x,y of the mouse click are sent to the ball and the position is updated. This doesn't work *at all*. I can't figure out why not.

Really any pointers in the right direction would help. At this point I click on the screen and the ball simply disappears though it should be bounded by upper and lower max y.

This is the move method.

synchronized public void move(){

if(climbing){

if(newY == upperMax){ // test if can no longer move upwards / hit an obstacle. If hit, change to falling

shootXApex = newX;

falling = true;

climbing = false;

}

if(launchX > newX && climbing){ // shoot target to the right

if(newX< (deltaX) && newX< pWidth - missileHeight) // hasn't reached maximum shot trajectory or hit wall

newX = newX + (deltaX/tempo); // shoot right

newY = newY + yInFlight; // shoot up

}

else if(climbing){

newX = newX - deltaX/tempo; // shoot left

newY = newY - yInFlight; // shoot up

}

if(newX == shootXApex ||newY< upperMax || newY== upperMax){

climbing = false;

falling = true;

}

} // end if shooting

if(falling && newY> lowerMax){

// add line to check for platform landing

if(0<launchVectorAngle && launchVectorAngle<90){

newX = newX + deltaX/tempo; // fall right

newY = newY + yInFlight; // fall downwards

}

else{

newX = newX - deltaX/tempo; // fall left

newY = newY + yInFlight; // fall downwards

}

if(newY> lowerMax|| landed){// player has landed or gone off screen

falling = false;

}

maxHeight = false;

}

}