CODEWITHSUNDEEP
java
Christine Austin
Christine Austin

Reputation: 93

Processing class giving NullPointException (Beginner)

Im trying to make a basic frogger game. All I am trying to do it make a class for my frog image, and then I want it have it shown under void draw(); Except I keep getting NullPointException, can anyone help me figure out why?

This is the code I've been playing with to try and figure out the issue. 

PImage img; // frog image

Frog froggy;
Car[] c1;

class Car {
  float xpos;
  int ypos;
  int sizel;
  int sizew;
  float yspeed;
  color c;

   Car(){
    xpos = 0;
    ypos = (int)random(120,480);
    sizel = (int)random(20,30);
    sizew = 15;
    yspeed = (float)random(1,3);
    c= color(random(255), random(255), random(255));

  }

  void carShape() {
    rectMode(CENTER);
    fill(c);
   rect(xpos,ypos,sizel,sizew);
   fill(0);
   rect(xpos-5, ypos-8, 8,5);
   rect(xpos+5, ypos-8, 8,5);
   rect(xpos-5, ypos+8, 8,5);
   rect(xpos+5, ypos+8, 8,5);

  }

 void moveCar () {
   xpos = xpos + yspeed;
    if (xpos > width) {
      xpos = 0;
      ypos = (int)random(120,480);

    } 

 } 
}

class Frog {
  int frogx;
  int frogy;

 Frog(){
    frogx = width/2-20;
    frogy = 527;
 }

  void drawFrog() {
    image(img,frogx,frogy);

 }
}

void setup() {
  size(800,600);
   img = loadImage("frog.png");


c1 = new Car[20];

  for(int i=0; i<20; i++) {
    c1[i] = new Car();
  }
}

  void draw() {
    background(100);

     froggy.drawFrog();


    for(int i=0; i<20; i++) {
    c1[i].carShape();
    c1[i].moveCar();
    }


  }

Heres the error

Exception in thread "Animation Thread" java.lang.NullPointerException
    at snowflakecarexample.draw(snowflakecarexample.java:97)
    at processing.core.PApplet.handleDraw(PApplet.java:2120)
    at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:197)
    at processing.core.PApplet.run(PApplet.java:1998)
    at java.lang.Thread.run(Thread.java:680)

Upvotes: 1

Views: 272

Answers (3)

PermGenError
PermGenError

Reputation: 46428

you din't initialize Frog object. try 

   Frog froggy = new Frog();
   froggy.drawfrog();

Upvotes: 3

NickD
NickD

Reputation: 351

In the moveCar() function you are checking if (xpos > width), but I don't see width declared anywhere. Unless it is declared and not in the snippet you have posted, this could be the issue.

You also use width in the Frog() function.

Upvotes: 0

tb-
tb-

Reputation: 1290

Whatever froggy should be, it must be initialized:

Frog froggy;
... (Froggy is null)
froggy.drawFrog();

perhaps you want to call a constructor somewhere? Like:

Frog froggy = new Frog();

Upvotes: 2

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