Java, private access in main()

Question

I am studying for the OCA Exam and came across this code:

public class Driver {

  private void printColor(String color) {
    color = "purple";
    System.out.print(color);
  }

  public static void main(String[] args) {
    new Driver().printColor("blue");
  }
}

The question asks "What is the outcome of this piece of code". I initially thought it will be "it does not compile" because you have an object instance trying to access a private method. But, it turns out to be "purple".

Why is it "purple" and not "it does not compile"? I know the Driver instances lives in the same class it is declared in, but why it still have the privilege to access private methods?

Thank you

Closely related: https://stackoverflow.com/questions/16586809/why-is-it-allowed-to-access-a-private-field-of-another-object — T.J. Crowder, Sep 17 '19 at 14:47
Alternative dupe: [Why can a “private” method be accessed from a different instance?](https://stackoverflow.com/questions/21900632/why-can-a-private-method-be-accessed-from-a-different-instance) — Ivar, Sep 17 '19 at 14:47
Possible duplicate of https://stackoverflow.com/questions/792361/do-objects-encapsulate-data-so-that-not-even-other-instances-of-the-same-class-c. — T.J. Crowder, Sep 17 '19 at 14:48
Thank you GBlodgett and khelwood. I **knew** there was one, I just couldn't find it. — T.J. Crowder, Sep 17 '19 at 14:50

score 2 · Answer 1 · answered Sep 17 '19 at 14:45

2

private means that the method is inaccessible outside the class.

Since your main method is inside the Driver class, then the private methods of Driver are accessible.

answered Sep 17 '19 at 14:45

Konstantin Yovkov

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it would make sense if `printColor("blue");` was called without creating an object. does compiler simply ignore the `Driver` object and treat that line as if no object was created? – mangusta Sep 17 '19 at 14:47
In this case `printColor()` (which is a non-static method) is called from a `static` context, which is not allowed. – Konstantin Yovkov Sep 17 '19 at 14:49
I know that, that's what I mean - if `printColor` is called from inside the class it is defined, then probably compiler implicitly treats it as a static method – mangusta Sep 17 '19 at 14:53
No, it implicitly treats it as an _instance_ method (it would be the same if `this.printColor()` is called). – Konstantin Yovkov Sep 17 '19 at 14:54

score 1 · Answer 2 · answered Sep 17 '19 at 14:46

1

I think you missunderstood what private means. It simply means: "You can't access this method from outside the Driver-class." And since you are inside the class, the compiler allows the access.

answered Sep 17 '19 at 14:46

Christian

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Java, private access in main()

2 Answers2