Why can a private member be return?

Question

The following sample code is from website.

sInstance is a private member, it means that it's only be access in the class LittleMonkProviderHolder.

Why can the function getInstance() return LittleMonkProviderHolder.sInstance ? Thanks!

Code

public class FloatActionController {

    private FloatActionController() {
    }

    public static FloatActionController getInstance() {
        return LittleMonkProviderHolder.sInstance;  //Return a private member!!!
    }


    private static class LittleMonkProviderHolder {
        private static final FloatActionController sInstance = new FloatActionController();
    }

}

the concept of access scopes is rather self-explanatory, when looking what the keywords exactly mean. — Martin Zeitler, Oct 26 '18 at 03:23
@MartinZeitler You might want to read the question again. It's a valid question, why can a private member be accessed by it's outer class. — Kartik, Oct 26 '18 at 03:24
@Kartik keyword `private` has access level `class`: https://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html - this can be an advance and dis-advance of inner classes, depending what one intends to accomplish. — Martin Zeitler, Oct 26 '18 at 03:27
Ah, I missed the key aspect of this question upon initial skimming. Indeed, the question is asking _"why is a (static) inner class private instance visible to the outer class."_ I was expecting the basic "type vs instance" question & crafted a useless explanatory answer before reading more closely. — michael, Oct 26 '18 at 04:41
looks like you are missing java basics. Take some time to go through some basic java tutorial to eliminate similar future questions. — Vladyslav Matviienko, Oct 26 '18 at 04:52

score 2 · Accepted Answer · edited Oct 28 '18 at 18:39

2

This looks like a Bill Pugh singleton to me. There is nothing wrong with returning a private member from a private inner class in the FloatActionController class. The private specifier only means that trying to access the field directly via:

FloatActionController.LittleMonkProviderHolder.sInstance

would fail, as both the inner class and its member are private.

edited Oct 28 '18 at 18:39

Dawood ibn Kareem

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answered Oct 26 '18 at 03:17

Tim Biegeleisen

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Why can a private member be return?

1 Answers1