# NullPointerExpection in for loop

**URL:** <https://discourse.processing.org/t/nullpointerexpection-in-for-loop/41150>\
**Category:** Beginners\
**Created:** [March 5, 2023, 10:52am UTC](https://discourse.processing.org/t/nullpointerexpection-in-for-loop/41150 "2023-03-05T10:52:02Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Aryszin](https://avatars.discourse-cdn.com/v4/letter/a/ec9cab/32.png) [@Aryszin](https://discourse.processing.org/u/Aryszin)\
**Post date:** [March 5, 2023, 10:52am UTC](https://discourse.processing.org/t/nullpointerexpection-in-for-loop/41150/1 "2023-03-05T10:52:02Z")

</div>

```auto
for(int i = maxlayers+1; i > 0; i-=1) {
      image(layers[i+1], xpos, ypos, xsize*zoomx, ysize*zoomy);
    }

```

This code for some reason just return “NPE NullPointerExpection” why? i dont know! thats why im asking you! Arys

---

<div class="post-metadata">

**Author:** ![quark](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/quark/32/26_2.png) [@quark](https://discourse.processing.org/u/quark)\
**Post date:** [March 5, 2023, 11:05am UTC](https://discourse.processing.org/t/nullpointerexpection-in-for-loop/41150/2 "2023-03-05T11:05:22Z")

</div>

> [@Aryszin](#):
>
> ```auto
> for(int i = maxlayers+1; i > 0; i-=1) {
> image(layers[i+1], xpos, ypos, xsize*zoomx, ysize*zoomy);
> }
> 
> ```

because the array is not big enough i.e. no index value at layers[maxlayers + 2] , when i = 1

```auto
for(int i = layers.length - 1; i > 0; i-=1) {
      image(layers[i], xpos, ypos, xsize*zoomx, ysize*zoomy);
}

```

---

<div class="post-metadata">

**Author:** ![quark](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/quark/32/26_2.png) [@quark](https://discourse.processing.org/u/quark)\
**Post date:** [March 5, 2023, 11:08am UTC](https://discourse.processing.org/t/nullpointerexpection-in-for-loop/41150/3 "2023-03-05T11:08:20Z")

</div>

I assume that there is an image at layers[0] in which case this is better

```auto
for(int i = layers.length - 1; i >= 0; i--) {
      image(layers[i], xpos, ypos, xsize*zoomx, ysize*zoomy);
}

```

`i--` decrements `i` by 1

---

<div class="post-metadata">

**Author:** ![Aryszin](https://avatars.discourse-cdn.com/v4/letter/a/ec9cab/32.png) [@Aryszin](https://discourse.processing.org/u/Aryszin)\
**Post date:** [March 5, 2023, 11:09am UTC](https://discourse.processing.org/t/nullpointerexpection-in-for-loop/41150/4 "2023-03-05T11:09:37Z")

</div>

thank you! it realy helps!