My program has 3 files -  a main, an avatar class that creates the player, and an opponent class that creates the opponent.

I want my avatar and opponent to be able to fire bullets. At first I thought about created a separate bullet class and pass in the vector locations of the player/opponent but that didn't work.

class Bullet{
      PVector pos;

      void draw(){
            ellipse(pos.x, pos.y, 10, 10);
      }

      void getLoc(PVector a){
            pos.x=a.x;
            pos.y=a.y;
      }
}

Then in main I had

Bullet fire;
fire=new PVector();

if ( key == ' ' ) {
    fire.getLoc( player.getPos() );
  }

I kept getting a null pointer exception. Anyone got any other ideas about how I can implement the bullet?