Investigating naming convention adherence in Java references

Naming conventions can help the readability and comprehension of code, and thus the onboarding of new developers. Conventions also provide cues that help developers and tools extract information from identifier names to support software maintenance. Tools exist to automatically check naming conventions but they are often limited to simple checks, e.g. regarding typography. The adherence to more elaborate conventions, such as the use of noun and verbal phrases in names, is not checked. We present Nominal, a naming convention checking library for Java that allows the declarative specification of conventions regarding typography and the use of abbreviations and phrases. To test Nominal, and to investigate the extent to which developers follow conventions, we extract 3.5 million reference - field, formal argument and local variable - name declarations from 60 FLOSS projects and determine their adherence to two well-known Java naming convention guidelines that give developers scope to choose a variety of forms of name, and sometimes offer conflicting advice. We found developers largely follow naming conventions, but adherence to specific conventions varies widely.