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A nested class is any class whose declaration occurs within the body of another class or interface \[[JLS 2005|AA. Bibliography#JLS 05]\]. Nested classes are a broad set of classes that are classified as {{static}} memberclasses and inner classes. "An inner class is a nested class that is not explicitly or implicitly declared {{static}}" \[[JLS 2005|AA. Bibliography#JLS 05]\]. An inner class may be local, anonymous, or non-static. |
The use of a nested class is error-prone unless the semantics are well understood. A common notion is that only the outer class can access the contents of the nested inner class(es). Not only does the nested class have access to the private fields of the outer class, the same fields can be accessed by another class in the package depending on whether the nested class is declared public or if it contains public methods /or constructors. By default, the javac compiler converts the accessibility of private methods of a nested class to package-private.
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Use the private access specifier for declaring hiding the inner class (es) and all contained methods and constructors. The compiler will refuse to compile AnotherClass because of its attempt to access a private nested class.
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