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public static final HashMap<IntegerHashMap&lt;Integer, String>String&gt; hm = new HashMap<IntegerHashMap&lt;Integer, String>String&gt;();

Compliant Solution

Mutable data members that are static must always be declared private.

private static final HashMap<IntegerHashMap&lt;Integer, String>String&gt; hm = new HashMap<IntegerHashMap&lt;Integer, String>String&gt;();

Exceptions

*EX1:* According to Sun's Code Conventions document \[[Conventions 09|AA. Java References#Conventions 09]\]:

One example of appropriate public instance variables is the case where the class is essentially a data structure, with no behavior. In other words, if you would have used a struct instead of a class (if Java supported struct), then it's appropriate to make the class's instance variables public.

*EX2:* ""if a class is package-private or is a {{private}} nested class, there is nothing inherently wrong with exposing its data fields - assuming they do an adequate job of describing the abstraction provided by the class. This approach generates less visual clutter than the accessor-method approach, both in the class definition and in the client code that uses it."" \[[Bloch 08|AA. Java References#Bloch 08]\]. This exception applies to both mutable as well as immutable fields.

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Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Other Languages

This rule appears in the C++ Secure Coding Standard as OBJ00-CPP. Declare data members private.

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08. Object Orientation (OBJ)            08. Object Orientation (OBJ)            OBJ01-J. Understand how a superclass can affect a subclass