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The Java compiler type-checks the arguments to a varargs method to ensure that they are of the same type or object reference. However, the compile-time checking is ineffective when two method signatures are used in particular - {{Object}} and the generic type {{T}} \[[Bloch 08|AA. Java References#Bloch 08]\]. Another requirement for providing strong compile-time type checking of variable argument methods is to be as specific as possible when declaring the type of the method parameter.

Noncompliant Code Example

This noncompliant code example declares two methods, one with an Object parameter and another with a generic type T. Both these approaches are flawed as they break strong compile-time type checking.

Code Block
bgColor#FFCCCC
ReturnType1 suspect1(Object... args) { }
<T> ReturnType2 suspect2(T... args) { }

Compliant Solution

Do not use generic types like Object in varargs and be as specific as possible when declaring parameter types.

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Also, note that autoboxing does not allow strong compile time type checking of primitive types and their corresponding wrapper classes.

Risk Assessment

Unmindful use of the varargs feature breaks strong compile-time type checking, creates ambiguity and diminishes code readability.

Rule

Severity

Likelihood

Remediation Cost

Priority

Level

DCL08- J

low

unlikely

medium

P2

L3

Automated Detection

TODO

Related Vulnerabilities

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

References

Wiki Markup
\[[Sun 06|AA. Java References#Sun 06]\] [varargs|http://java.sun.com/j2se/1.5.0/docs/guide/language/varargs.html] 
\[[Bloch 08|AA. Java References#Bloch 08]\] Item 42: "Use varargs judiciously"
\[[Steinberg 05|AA. Java References#Steinberg 05]\] "Using the Varargs Language Feature"

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