Class structure
- 'private' method declared 'final'
Reports methods that are marked with both final and private keywords.
- 'public' constructor can be replaced with factory method
Reports public constructors.
- 'static' method declared 'final'
Reports static methods that are marked as final.
- 'static', non-'final' field
Reports non-final static fields.
- Abstract 'class' may be 'interface'
Reports abstract classes that can be converted to interfaces.
- Anonymous class can be replaced with inner class
Reports anonymous classes.
- Class is closed to inheritance
Reports classes that are declared final.
- Class may extend adapter instead of implementing listener
Reports classes implementing listeners instead of extending corresponding adapters.
- Class name differs from file name
Reports top-level class names that don't match the name of a file containing them.
- Class with only 'private' constructors should be declared 'final'
Reports classes with only private constructors.
- Constant declared in 'abstract' class
Reports constants (public static final fields) declared in abstract classes.
- Constant declared in interface
Reports constants (public static final fields) declared in interfaces.
- Empty class
Reports empty classes and empty Java files.
- Field can be local
Reports redundant class fields that can be replaced with local variables.
- Inner class of interface
Reports inner classes in interface classes.
- Interface may be annotated as '@FunctionalInterface'
Reports interfaces that can be annotated with @FunctionalInterface (available since JDK 1.8).
- Local class
Reports local classes.
- Marker interface
Reports marker interfaces without any methods or fields.
- Method can't be overridden
Reports methods that are declared final.
- Method returns per-class constant
Reports methods that only return a constant, which may differ for various inheritors.
- Multiple top level classes in single file
Reports multiple top-level classes in a single Java file.
- No-op method in 'abstract' class
Reports no-op (for "no operation") methods in abstract classes.
- Non-'static' initializer
Reports non-static initializers in classes.
- Non-final field in 'enum'
Reports non-final fields in enumeration types.
- Singleton
Reports singleton classes.
- Utility class
Reports utility classes.
- Utility class can be 'enum'
Reports utility classes that can be converted to enums.
- Utility class is not 'final'
Reports utility classes that aren't final or abstract.
- Utility class with 'public' constructor
Reports utility classes with public constructors.
- Utility class without 'private' constructor
Reports utility classes without private constructors.
- Value passed as parameter never read
Reports redundant method parameters that can be replaced with local variables.