# Two syntax questions about arrays and classes
**URL:** https://discourse.processing.org/t/two-syntax-questions-about-arrays-and-classes/7869
**Category:** Beginners
**Created:** [January 26, 2019, 11:49pm UTC](https://discourse.processing.org/t/two-syntax-questions-about-arrays-and-classes/7869 "2019-01-26T23:49:06Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@femke.blanco](https://discourse.processing.org/u/femke.blanco)
#### Post date: [January 26, 2019, 11:49pm UTC](https://discourse.processing.org/t/two-syntax-questions-about-arrays-and-classes/7869/1 "2019-01-26T23:49:06Z")
Hi
Apologies if these are newbie questions. I have just begun processing.
(The full code is at the end of the post.)
Question 1: When initialising an array with a “for” loop, why do I have to do so within void setup()? Why can’t I do this before void setup()? That is to say, why can’t I write the following:
```auto
Class[] array = new Class[10];
for(int i = 0; i < array.length; i = i + 1) {
array[i] = new Class(0, i*50);
}
void setup() {
size(500, 500);
}
```
Question 2: When defining a class, why do I have to declare the class’ variables before the constructor? Why can’t I do this within the constructor? That is to say, why can’t I write the following:
```auto
class Class {
Class(int tempX, int tempY) {
int X = tempX;
int Y = tempY;
}
```
Thanks in advance.
The full code:
```auto
Class[] array = new Class[10];
void setup() {
size(500, 500);
for(int i = 0; i < array.length; i = i + 1) {
array[i] = new Class(0, i*50);
}
}
void draw() {
background(255);
for(int i = 0; i < array.length; i = i + 1) {
array[i].composeNmove(i);
}
}
class Class {
int X;
int Y;
Class(int tempX, int tempY) {
X = tempX;
Y = tempY;
}
void composeNmove(int change) {
fill(255);
ellipseMode(CENTER);
ellipse(X, Y, 50, 50);
X = X + change;
if (X >500) {
X = 0;
}
}
}
```
---
### Author:  [@GoToLoop](https://discourse.processing.org/u/GoToLoop)
#### Post date: [January 27, 2019, 12:15am UTC](https://discourse.processing.org/t/two-syntax-questions-about-arrays-and-classes/7869/2 "2019-01-27T00:15:00Z")
> [@femke.blanco](#):
>
> Why can’t I do this before `void setup()`?
Actually we can! Just wrap those statements within a curly braces block:
```auto
Class[] array = new Class[10];
{
for (int i = 0; i < array.length; ++i) {
array[i] = new Class(0, i*50);
}
}
```
Those are called initialization blocks btW.
And they’re run before their class’ constructors, together w/ field declarations.
Statements outside any initialization blocks, functions and field declarations aren’t allowed in Java.
> [@femke.blanco](#):
>
> When defining a class, why do I have to declare the class’ variables before the constructor?
Class’ variables are called fields in Java.
In Java, all class members need to be well-defined.
Members can’t be added on-the-fly to a class later.
And variables declared within methods aren’t fields, but local variables.
---
### Author:  [@Architector\_4](https://discourse.processing.org/u/Architector_4)
#### Post date: [January 27, 2019, 12:40am UTC](https://discourse.processing.org/t/two-syntax-questions-about-arrays-and-classes/7869/3 "2019-01-27T00:40:53Z")
> [@femke.blanco](#):
>
> Question 2: When defining a class, why do I have to declare the class’ variables before the constructor? Why can’t I do this within the constructor?
An easy way to think about this: Anything that is defined in curly brackets, stays in the curly brackets.
So, if you have a pair of `{` and `}` brackets, anything that is defined inside of them, regardless of what these brackets mean, can only be accessed from within these brackets, and is essentially lost and then eventually garbage-collected by Java when it gets to that `}`.
Obviously this doesn’t apply if you modify something that was made before curly brackets, which is why answer to the first question by @GoToLoop works.
I mean, it probably doesn’t, but it’s helpful and easier to think about it that way.
Also, you can define your array as:
```auto
Class[] array = {new Class(0,0), new Class(0,50), new Class(0,100) }; //...
```
And, uh, in that case, brackets count as you are modifying that array you created outside of them, not defining new things.