Basic Java question: Accessing private class variables

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pompa

Basic Java question: Accessing private class variables

in Programming Questions • 2 months ago

I guess I'm confused about private variables in Java. To generalize this as much as possible for Processing, here's some simple code:

class Thing {
private int member;
}
void setup() {
size(1, 1, P2D);
Thing thing = new Thing();
thing.member = 1; // why can I do this?
exit();
}

Here, member is private, so why am I able to access it from outside of the class directly?

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GoToLoop

Re: Basic Java question: Accessing private class variables

2 months ago

B/c Thing isn't a regular top-class as we normally would expect in Java.
It's a nested class living within your own "sketch". The "sketch" itself is the top-class.
When a nested class isn't static, it's also called an inner class.

Processing wraps around the code from all its tabs as 1 big Java top-level class.
So any other classes we create end up as an nested class instead.

Nested class can see any resources from each classes above it.
The same way, a topper class can see anything from instantiated lower-classes.

There's no way to hide anything from each other that I know about.
Access declaration private in that case would only affect other classes which belong to other top-class levels.

The only solution would be to make class Thing a top-class itself.
To do that, create another tab w/ the same name as the class you wanna put in there.
However, suffix that w/ -> .java.

For example, for a top-class level named Thing, its tab's name is -> "Thing.java".

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