Java private modifier confusion

Question

I've been writing Java for some years, but I still do not understand why this simple example class below actually passes compilation. In this situation, I would make a getter method for myInt, and use that method to fetch the myInt from o in my compareTo method, as myInt is declared private. Could someone please tell me why on earth this is a legal way to access o's myInt?

public class B implements Comparable<B> {

    private int myInt = 0;

    public int compareTo(B o) {
        return myInt-o.myInt;
    }

}

Thanks in advance!

`private` has `class` scope. You are still in the same class. — PM 77-1, Mar 01 '15 at 20:14
You are already in the same class with B. Private members are accessible from the same class. Check: http://docs.oracle.com/javase/tutorial/java/javaOO/variables.html Access Modifiers private modifier—the field is accessible only within its own class. — Onur Aktaş, Mar 01 '15 at 20:15
" a class always has access to its own members" - http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html — doog abides, Mar 01 '15 at 20:16
Thanks guys, I assumed that was the reason. Post it as an answer and I'll be glad to accept. — Henrik Hillestad Løvold, Mar 01 '15 at 20:16

davide · Accepted Answer · 2017-09-05T07:01:42.270

3

According to Oracle's Java Tutorial

Access level modifiers determine whether other classes can use a particular field or invoke a particular method.

Access level has been designed at the class level, and it does not depends on instances.

edited Sep 05 '17 at 07:01

answered Mar 01 '15 at 20:20

davide

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score 1 · Answer 2 · answered Mar 01 '15 at 20:27

According to Java API:

The private modifier specifies that the member can only be accessed in its own class.

As a class always has access to its own members. Your codes are allowed and it will not give your compilation error.

Take a look at this (Changing B to C):

class B implements Comparable<B> {

    private int myInt = 0;

    public int compareTo(C o) {
        return myInt-o.myInt;
    }

}

class C
{
    private int myInt = 0;
}

If you try changing B to C (another class). It will give you compilation error.

Java private modifier confusion

2 Answers2