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The enhanced for statement introduced in Java 1.5, commonly referred to as the for-each idiom, finds primary application in iterating over collections of objects. While similar to the usual for statement, this idiom cannot be used to assign values or initialize datato the loop variable.

Noncompliant Code Example

The intention behind this noncompliant example is to initialize a Character array using a for-each idiom. Unbeknownst to the developeran enhanced for loop. However, because the loop variable cannot be assigned to, the array is not suitably initialized. This is because it is impossible to carry out assignments from within a for-each loop.

Character[] array = new Character[10];
for(Character c: array) 
  c = 'x'; // initialization attempt

for(int i=0;i<array.length;i++) 
  System.out.print(array[i]);	    // prints 10 "null"s

Compliant Solution

This compliant solution correctly initializes the array using a for loop.

Character[] array = new Character[10];
for(int i=0;i<array.length;i++) 
  array[i] = 'x';

Risk Assessment

Attempts to initialize data assign to the loop variable from within the enhanced for loop (for-each idiom) will be futile and will may leave the class in a fragile, inconsistent state.

Automated Detection

TODO

Related Vulnerabilities

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

Other Languages

TODO

References

\[[JLS 05|AA. Java References#JLS 05]\] Section [14.14.2|http://java.sun.com/docs/books/jls/third_edition/html/statements.html#14.14.2] "The enhanced for statement"

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