Contents - Cultural View

Java syntax 194
}
AUTUMN {
};
Interfaces
String getDescription() {return "cooler";}
Interfaces are data structures that contain member definitions and not actual implementation. They are useful to
define a contract between members in different types that have different implementations. Every interface is
implicitly abstract. The only modifier allowed to use with interfaces apart from access modifiers is strictfp, which
has the same effect as for classes.
interface ActionListener {
}
int ACTION_ADD = 0;
int ACTION_REMOVE = 1;
void actionSelected(int action);
Implementing an interface
An interface is implemented by a class using the implements keyword. It is allowed to implement more than one
interface, in which case they are written after implements keyword in a comma-separated list. Class implementing an
interface must override all its methods, otherwise it must be declared as abstract.
interface RequestListener {
}
int requestReceived();
class ActionHandler implements ActionListener, RequestListener {
}
void actionSelected(int action) {
}
public int requestReceived() {
}
//Calling method defined by interface
RequestListener listener = new ActionHandler(); /*ActionHandler can be
represented as RequestListener...*/
listener.requestReceived(); /*...and thus is known to implement
requestReceived() method*/