# Boolean function inside a class not working

**URL:** <https://discourse.processing.org/t/boolean-function-inside-a-class-not-working/29426>\
**Category:** Beginners\
**Created:** [April 16, 2021, 8:00pm UTC](https://discourse.processing.org/t/boolean-function-inside-a-class-not-working/29426 "2021-04-16T20:00:22Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![iudividnal](https://avatars.discourse-cdn.com/v4/letter/i/22d042/32.png) [@iudividnal](https://discourse.processing.org/u/iudividnal)\
**Post date:** [April 16, 2021, 8:00pm UTC](https://discourse.processing.org/t/boolean-function-inside-a-class-not-working/29426/1 "2021-04-16T20:00:22Z")

</div>

Hey there i was creating an animation for a simple game im working on and run into a problem where my simple boolean function inside a class returns an error “NullPointerException”

```auto
int randomHue;
int rainbowHue;

boolean draw_startup_TaskAnim = false;

color bgr = color(230, 230, 250);

TaskAnim startup_TaskAnim;

void setup () {
  size(450, 800);
}

void draw () {
  colorMode(RGB);
  background(bgr);

  if (draw_startup_TaskAnim) {
    startup_TaskAnim.grow();
    startup_TaskAnim.display();
  }

  if (startup_TaskAnim.end() == true) {
    draw_startup_TaskAnim = false;
    fill(color(randomHue, 80, 90));
    rect(width / 2, height / 2, 25, 25);

    println(" **works**");
  }
}

void mousePressed() {

  randomHue = randomHue();
  startup_TaskAnim = new TaskAnim (100, 20, 0, 5, width * 2, color(randomHue, 80, 90));
  draw_startup_TaskAnim = true;
}

class TaskAnim {
  float xpos;
  float ypos;
  float animSize;
  float maxSize;
  float growth;

  color animFill;

  TaskAnim(float temp_xpos, float temp_ypos, float temp_animSize, float temp_growth, int temp_maxSize, color temp_animFill) {

    xpos = temp_xpos;
    ypos = temp_ypos;
    animSize = temp_animSize;
    growth = temp_growth;
    maxSize = temp_maxSize;

    animFill = temp_animFill;
  }

  void display () {
    colorMode(HSB, 100);
    fill(animFill);
    stroke(animFill);
    ellipse(xpos, ypos, animSize, animSize);

    colorMode(RGB);
    fill(bgr);
    noStroke();
    rect(0, height /10 + 1, width, height);
  }

  void grow () {

    animSize = animSize + growth;
  }

  void growStop () {
    growth = 0;
  }

  boolean end () {    
    if (animSize > maxSize) {
      return true;
    } else {
      return false;
    }
  }
}

int randomHue() {  
  colorMode(HSB, 100);
  randomHue = int(random(1, 100));
  return randomHue;
}

```

---

<div class="post-metadata">

**Author:** ![Chrisir](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/chrisir/32/45_2.png) [@Chrisir](https://discourse.processing.org/u/Chrisir)\
**Post date:** [April 16, 2021, 8:28pm UTC](https://discourse.processing.org/t/boolean-function-inside-a-class-not-working/29426/2 "2021-04-16T20:28:05Z")

</div>

> [@iudividnal](#):
>
> `startup_TaskAnim`

Maybe this is causing the error?

Because you define / instantiate it only in mousePressed()

So in draw() it is null

The boolean function looks okay

---

<div class="post-metadata">

**Author:** ![jb4x](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/jb4x/32/789_2.png) [@jb4x](https://discourse.processing.org/u/jb4x)\
**Post date:** [April 16, 2021, 8:35pm UTC](https://discourse.processing.org/t/boolean-function-inside-a-class-not-working/29426/3 "2021-04-16T20:35:13Z")

</div>

As @Chrisir said, you are trying to access method of an object that is not created so it does not exist in memory and thus the NullPointerException.

To prevent that, you can add the following piece of code at the beginning of your draw() loop:

```auto
if (startup_TaskAnim == null) {
  return;
}

```

Or simply create the object in the setup() method.

---

<div class="post-metadata">

**Author:** ![iudividnal](https://avatars.discourse-cdn.com/v4/letter/i/22d042/32.png) [@iudividnal](https://discourse.processing.org/u/iudividnal)\
**Post date:** [April 17, 2021, 10:26am UTC](https://discourse.processing.org/t/boolean-function-inside-a-class-not-working/29426/4 "2021-04-17T10:26:12Z")

</div>

Thans a lot for your help and fast reply, i just couldnt see this basic mistake before.