CompareToWithoutComparable.md

Pattern: compareTo() without Comparable

Issue: -

Description

If you implement a compareTo() method then you should also implement the Comparable interface. If you don't then you could possibly get an exception if the Groovy == operator is invoked on your object. This is an issue fixed in Groovy 1.8 but present in previous versions.

Here is an example of code that produces a violation:

class BadClass {
    int compareTo(Object o) { ... }
}

Known limitations:

• This rule is not able to determine if the class extends a superclass that itself implements Comparable, or if it implements an interface that extends Comparable. In those cases, this rule produces a false violation.

Further Reading

• CodeNarc - CompareToWithoutComparable