Implements Bloch, Effective Java, Item 17 - Use Interfaces only to define types. According to Bloch, an interface should describe a type. It is therefore inappropriate to define an interface that does not contain any methods but only constants. The Standard class javax.swing.SwingConstants is an example of a class that would be flagged by this check. The check can be configured to also disallow marker interfaces like java.io.Serializable, that do not contain methods or constants at all.

This rule is deprecated, use {rule:squid:S1214} instead.