# Adding integer to an array (Java)

**URL:** <https://discourse.processing.org/t/adding-integer-to-an-array-java/7247>\
**Category:** Beginners\
**Created:** [January 6, 2019, 12:20pm UTC](https://discourse.processing.org/t/adding-integer-to-an-array-java/7247 "2019-01-06T12:20:02Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![J0R1AN](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/j0r1an/32/7498_2.png) [@J0R1AN](https://discourse.processing.org/u/J0R1AN)\
**Post date:** [January 6, 2019, 12:20pm UTC](https://discourse.processing.org/t/adding-integer-to-an-array-java/7247/1 "2019-01-06T12:20:02Z")

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Hello everyone,

I was experimenting a bit with arrays and integers but I found myself having trouble with adding numbers to an array. I want to create an array, add a number to the array (so the length increases) and print all numbers in the array one by one. Here’s what I’ve got so far:

```auto
int[] numbers = {1, 2, 3};

void setup() {
  numbers.add(4); // <--This code doesn't work and needs to be changed, but to what?
  for(int i = 0; i < numbers.length; i++) {
    print(numbers[i]);
  }
}

void draw() {}

```

now my output is:

```auto
123

```

and I want it to be:

```auto
1234

```

Any help would be greatly appreciated.  
Now that this has been solved, for anyone wanting to learn about ArrayLists too here’s a great video explaining it all: [[Video]](https://www.youtube.com/watch?v=HnSJZ4qTcwY)

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<div class="post-metadata">

**Author:** ![matthewortega](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/matthewortega/32/309_2.png) [@matthewortega](https://discourse.processing.org/u/matthewortega)\
**Post date:** [January 6, 2019, 12:32pm UTC](https://discourse.processing.org/t/adding-integer-to-an-array-java/7247/2 "2019-01-06T12:32:54Z")

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Hey there,

This has always boggled my mind a bit too, since it’s so easy to do in other languages. But the best way to do this in Java would be to use an ArrayList or List. If you want to start out with the initial list, you have to import java.util.\* to give you the Arrays.asList method.

```auto
import java.util.*;

ArrayList<Integer> numbers;

numbers = new ArrayList<Integer>(Arrays.asList(1, 2, 3));

println(numbers);

numbers.add(10);

//prints 1,2,3

println(numbers);

// prints 1,2,3,10

```

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<div class="post-metadata">

**Author:** ![GoToLoop](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/gotoloop/32/86_2.png) [@GoToLoop](https://discourse.processing.org/u/GoToLoop)\
**Post date:** [January 6, 2019, 12:35pm UTC](https://discourse.processing.org/t/adding-integer-to-an-array-java/7247/3 "2019-01-06T12:35:16Z")

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[Processing.org/reference/append\_.html](http://Processing.org/reference/append_.html)

[Processing.org/reference/IntList.html](http://Processing.org/reference/IntList.html)

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**Author:** ![Architector\_4](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/architector_4/32/813_2.png) [@Architector\_4](https://discourse.processing.org/u/Architector_4)\
**Post date:** [January 6, 2019, 3:25pm UTC](https://discourse.processing.org/t/adding-integer-to-an-array-java/7247/4 "2019-01-06T15:25:52Z")

</div>

Usually, as mentioned above, it’s better to use a special type of array called `ArrayList` if that’s your intention, as `thing[]` type arrays are meant to be static length, i.e. not changing at all.

However, in Processing, there’s a function that takes an array and a thing you want to add to it, makes a new array out of that, and returns the resulting array to you.

So, what you should do instead of `numbers.add(4);` is to do `numbers = append(numbers,4);`

And, as noted in this function’s page in Processing reference, it sometimes may cause an error because that function wasn’t designed to work with arrays of any type - so, if you have an array `thing[] myArray = ...;`, and you want to `append` `something` to it, you would need to do :  
`myArray = (thing[]) append(myArray,something);`  
so that it would convert the result of `append` function to `thing[]`.

When you get experienced with the language though, again, I suggest using `ArrayList` for intentions like this as it’s meant to be dynamically resizable from the beginning, which will give you better performance - it will make noticeable difference when you’ll need to add an element to your array a few million times! 😃

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<div class="post-metadata">

**Author:** ![J0R1AN](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/j0r1an/32/7498_2.png) [@J0R1AN](https://discourse.processing.org/u/J0R1AN)\
**Post date:** [January 6, 2019, 5:54pm UTC](https://discourse.processing.org/t/adding-integer-to-an-array-java/7247/5 "2019-01-06T17:54:16Z")

</div>

Thanks a lot! This helped and I think I understand now 😀