ClassMemberImpliedModifier.md

Pattern: Use of implicit modifier on class members

Issue: -

Description

Checks for implicit modifiers on nested types in classes.

Nested enums and interfaces within a class are always static and as such the compiler does not require the static modifier. This check provides the ability to enforce that the static modifier is explicitly coded and not implicitly added by the compiler.

public final class Person {
  enum Age {  // violation
    CHILD, ADULT
  }
}

Rationale for this check: Nested enums and interfaces are treated differently from nested classes as they are only allowed to be static. Developers should not need to remember this rule, and this check provides the means to enforce that the modifier is coded explicitly.

Examples

This example checks that all implicit modifiers on nested interfaces and enums are explicitly specified in classes.

Configuration:

<module name="ClassMemberImpliedModifier" />

Code:

public final class Person {
  static interface Address1 {  // valid
  }

  interface Address2 {  // violation
  }

  static enum Age1 {  // valid
    CHILD, ADULT
  }

  enum Age2 {  // violation
    CHILD, ADULT
  }
}

Further Reading

• checkstyle - ClassMemberImpliedModifier