Analysis Details

Enforce noninstanciability with a private constructor

es.uniovi.reflection.analyses.bloch.2.4

This rule detects classes that have only static members but lack a private constructor. These classes are designed to be static so, in order to prevent their instantiation, they must implement (at least) a private constructor and no other constructors with a higher access level.

Computational Reflection Research Group

09-30-2026 22:23

Bad Practice

Class Declaration

MATCH (enclosingCU:ORDINARY_CU)-[:DECLARES_TYPE |  HAS_NESTED_TYPE]->(classDefinition:CLASS_DEC{isAbstract:FALSE})
WHERE classDefinition:TOP_LEVEL_TYPE OR NOT classDefinition.isInner
OPTIONAL MATCH (classDefinition)-[:DECLARES_FIELD | DECLARES_METHOD]->(staticMember {isStatic: true})
WITH enclosingCU, classDefinition, staticMember
WHERE staticMember IS NOT NULL AND 
NOT EXISTS ((classDefinition)-[:DECLARES_METHOD]->({isStatic: FALSE})) AND 
NOT EXISTS ((classDefinition)-[:DECLARES_FIELD]->({isStatic: FALSE})) AND 
(NOT EXISTS ((classDefinition)-[:DECLARES_CONSTRUCTOR]->({accessLevel: 'private'})) OR
EXISTS {(classDefinition)-[:DECLARES_CONSTRUCTOR]->(anotherCons) WHERE anotherCons.accessLevel<> 'private'}) 
RETURN DISTINCT '{"node":"'+classDefinition.fullyQualifiedName+'","line":"'+classDefinition.lineNumber+'","column":"'+classDefinition.column+'","rule":"BLOCH-2.4","location":"'+enclosingCU.fileName+'","message":"You should include a private constructor and no other constructor with higher access level in static class '+classDefinition.simpleName+' in order to enforce non-instantiability"}'