Java – Differences Between Public, Protected, Package-Private, and Private Access Modifiers

access-modifiersjavaprivateprotectedpublic

In Java, are there clear rules on when to use each of access modifiers, namely the default (package private), public, protected and private, while making class and interface and dealing with inheritance?

Best Answer

The official tutorial may be of some use to you.

	Class	Package	Subclass (same pkg)	Subclass (diff pkg)	World
`public`	+	+	+	+	+
`protected`	+	+	+	+
no modifier	+	+	+
`private`	+

+ : accessible
blank : not accessible

Related Solutions

Java Protected Modifier – Understanding Access and Visibility

What's going on here?

You've misunderstood the meaning of protected. You can access the protected members declared in A from within C, but only for instances of C or subclasses of C. See section 6.6.2 of the JLS for details of protected access. In particular:

Let C be the class in which a protected member is declared. Access is permitted only within the body of a subclass S of C.

In addition, if Id denotes an instance field or instance method, then:

[...]

If the access is by a field access expression E.Id, where E is a Primary expression, or by a method invocation expression E.Id(. . .), where E is a Primary expression, then the access is permitted if and only if the type of E is S or a subclass of S.

(Emphasis mine.)

So this code would be fine:

C c = new C();
System.out.println(c.publicInt);
System.out.println(c.protectedInt);

Best Answer

Related Solutions

Java Protected Modifier – Understanding Access and Visibility

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