The Controversial Ruleset contains rules that, for whatever reason, are considered controversial. They are separated out here to allow people to include as they see fit via custom rulesets. This ruleset was initially created in response to discussions over UnnecessaryConstructorRule which Tom likes but most people really dislike :-) This rule detects when a constructor is not necessary; i.e., when there's only one constructor, it's public, has an empty body, and takes no arguments. 3 Assigning a "null" to a variable (outside of its declaration) is usually bad form. Some times, the assignment is an indication that the programmer doesn't completely understand what is going on in the code. NOTE: This sort of assignment may in rare cases be useful to encourage garbage collection. If that's what you're using it for, by all means, disregard this rule :-) 3 A method should have only one exit point, and that should be the last statement in the method. 3 0) { return "hey"; // oops, multiple exit points! } return "hi"; } } ]]> Fields in interfaces are automatically public static final, and methods are public abstract. Classes or interfaces nested in an interface are automatically public and static (all nested interfaces are automatically static). For historical reasons, modifiers which are implied by the context are accepted by the compiler, but are superfluous. 3 Avoid assignments in operands; this can make code more complicated and harder to read. 3 Each class should declare at least one constructor. 3 Avoid importing anything from the 'sun.*' packages. These packages are not portable and are likely to change. 4 A suspicious octal escape sequence was found inside a String literal. The Java language specification (section 3.10.6) says an octal escape sequence inside a literal String shall consist of a backslash followed by: OctalDigit | OctalDigit OctalDigit | ZeroToThree OctalDigit OctalDigit Any octal escape sequence followed by non-octal digits can be confusing, e.g. "\038" is interpreted as the octal escape sequence "\03" followed by the literal character "8". 3 It is a good practice to call super() in a constructor. If super() is not called but another constructor (such as an overloaded constructor) is called, this rule will not report it. 3 0 ] /ClassOrInterfaceBody /ClassOrInterfaceBodyDeclaration /ConstructorDeclaration[ count (.//ExplicitConstructorInvocation)=0 ] ]]> Sometimes expressions are wrapped in unnecessary parentheses, making them look like a function call. 3 Use explicit scoping instead of the default package private level. 3 Use bitwise inversion to invert boolean values - it's the fastest way to do this. See http://www.javaspecialists.co.za/archive/newsletter.do?issue=042&locale=en_US for specific details 3 The dataflow analysis tracks local definitions, undefinitions and references to variables on different paths on the data flow. From those informations there can be found various problems. 1. UR - Anomaly: There is a reference to a variable that was not defined before. This is a bug and leads to an error. 2. DU - Anomaly: A recently defined variable is undefined. These anomalies may appear in normal source text. 3. DD - Anomaly: A recently defined variable is redefined. This is ominous but don't have to be a bug. 5 dd-anomaly foo(buz); buz = 2; } // buz is undefined when leaving scope -> du-anomaly } ]]> 3 1 2 2 3 2