无法使我的Java程序正常工作

Question

I have this program where I want the speed of the ball to move quicker when it is clicked on. Here are the two classes:

import processing.core.*;
public class Ball {

int xPos = 0;
int xDir = 1;
int speed = 1;
PApplet parent;


Ball (int _x, PApplet p){
xPos = _x;
parent = p;
}

void move() {
xPos = xPos + xDir * speed;
if (xPos>400-20 || xPos<20)
{
xDir =-xDir;
    }
}

void speedUp() {
    speed=speed+1;  
}

void display() {
parent.ellipse(xPos, 200, 40, 40);   
}

void run(){
      move();
      display();
  }
}

and

import processing.core.*;
public class Game extends PApplet{

public static void main(String args[]){
    PApplet.main(new String[] { "--present", "Game" });
}

Ball b1 = new Ball(xPos,this);

public void setup()
{
  size (400, 400);
  smooth();
  background(0);
  noStroke();
  fill(255);
}

public void draw()
{
  background(0);
  b1.run();
}

public void mousePressed()
  {
    if (dist(mouseX, mouseY, xPos, 200)<=20)
    {
        b1.speedUp();   
    }
  } 
}

I can't find a way to reference to xPos in my Game client so when I click on the ball it will pick up speed. I'm using processing, even though I am not too familiar with it. But it is a requirement in my project. Need help desperately!

Answer 1

Ball b1 = new Ball(xPos,this); 

do you have a xpos in the parent applet? else you have to pass some starting number like 10 and expost a getXPos() in Ball.

Also I see that you call the run method in the draw method. who calls draw? If its only when repainting then the ball wont be animate. Need to make a thread to make the ball move every second or so.

NOTE This should be obvious : even if you add getXPos() in Ball you cannot use it in the constructor of Ball. So you must seed it with some other value.