Java Instance Variable Accessibility

What is the difference in the accessibility of the following variables in Java?

public class Joe {
    public int a;
    protected int b;
    private int b;
    int c;
}

I'm most interested in what the last one is doing.

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public: read/writable for anyone

protected: read/writable for instances of subclasses and from within the enclosing package

private: read/writable for any instance of the class and inner or outer (enclosing) instance

int c : package-private, read/writable for all classes inside same package

See the JLS for more details

EDIT: Added the comment for protected stating that access is granted from inside same package, you guys are totally right. Also added comment for private. I remember now... ;-)

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Sorry for answering corrections to one previous answer but I don't have enough reputation to modify directly...

public - read/writable for anyone

protected - read/writable for instances subclasses and all classes inside same package

int c : package-private, read/writable for all classes inside same package

private - read/writable for any member of that class itself and inner classes (if any)

It is better to order the access modifiers this way, from the broadest access (public) to the narrowest (private), knowing that when going from narrow to broad, you don't lose any possibilities.

That's particularly important for "protected", where it is often misunderstood that classes in the same package can also access protected members of a class (not only its subclasses).

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I try to avoid package level access completely (the last access you mention).

I like to keep classes self-contained. If another class needs access to something in my class it should be public (and it should by a method, not an attribute). Otherwise I feel you've broken encapsulation, as explained in Abstraction VS Information Hiding VS Encapsulation.

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