A Single Abstract Method (SAM) interface is a Java interface containing only one method. The Java API is full of SAM interfaces, such as
java.lang.Runnable, java.awt.event.ActionListener, java.util.Comparator and
java.util.concurrent.Callable. SAM interfaces have a special place in Java 8 because they can be implemented using Lambda expressions or
Method references.
Using @FunctionalInterface forces a compile break when an additional, non-overriding abstract method is added to a SAM, which would
break the use of Lambda implementations.
Note that this rule is automatically disabled when the project's sonar.java.source is lower than 8.
public interface Changeable<T> {
public void change(T o);
}
@FunctionalInterface
public interface Changeable<T> {
public void change(T o);
}
This rule is deprecated, and will eventually be removed.