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NullPointerException Error

[3 Replies]
- 18-Mar-2012 11:25 AM
- Forum: Programming Questions
Hey guys,

I seem to have run into a problem with my code involving 'NullPointerException' which I'm not too sure what it means. When I try to run my code this error message pops up:

Exception in thread "Animation Thread" java.lang.NullPointerException

at leztrydisagain_w_oPVECTOR$Fish.detectBound(leztrydisagain_w_oPVECTOR.java:293)

at leztrydisagain_w_oPVECTOR.draw(leztrydisagain_w_oPVECTOR.java:66)

at processing.core.PApplet.handleDraw(PApplet.java:1631)

at processing.core.PApplet.run(PApplet.java:1530)

at java.lang.Thread.run(Thread.java:613)

My code reads:

class Fish {

  PVector pos, vel;

  PVector waveSpeed;

  float wave, amp;

  float xScale, bSize;

  float tankX, tankY, tankW, tankH;

  //boolean alive;

  color bColor;

  Fish(PVector pos, PVector vel, float wave, float amp, float xScale, float bSize) {

   pos= pos;

   vel= vel;

   wave= wave;

   amp= amp;

   xScale= xScale;

   bSize= bSize;

   bColor= color(random(255), random(255), random(255));

  }



  void detectBound() {

   if (pos.x+ bSize/2 > width) {               //this is the part it highlights

   pos.y= width- bSize/2;

   vel.x*= -1;

   }

   if (pos.x- bSize/2 < 0) {

   pos.x= bSize;

   vel.x*= -1;

   }

   if (pos.y+ bSize/2 > height) {

   pos.y= height- bSize/2;

   vel.y*= -1;

   }

   if (pos.y- bSize/2 < 0) {

   pos.y= bSize/2;

   vel.y*= -1;

   }

  }

  void update() { //changing the position of fish at random speed

   pos.x += vel.x;

   pos.y += vel.y+2*sin(wave)*amp;

  }

  boolean detectCollision(Fish otherFish) {

   if (abs(pos.x- otherFish.pos.x)< (bSize/2+ otherFish.bSize/2) && abs(pos.y- otherFish.pos.y)< (bSize/2+ otherFish.bSize/2)) {

   return true;

   }

   return false;

  }

  void bounce(Fish otherFish) {

   float angle = atan2(pos.y - otherFish.pos.y, pos.x - otherFish.pos.x);

   vel.x = 1 * cos(angle);

   vel.y = 1 * sin(angle);

   otherFish.vel.x = 1 * cos(angle - PI);

   otherFish.vel.y = 1 * sin(angle - PI);

  }

  void destroy(ArrayList fishies) {

   fishies.remove(this);

  }

}

Any solutions?

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