Optional method in Java Interface

Question

I have an interface with several method definitions, and I would not like to require some of them.

Is this possible? if so, how can i implement this

Answer 1

Although I agree with the other answers, one should note that such optional methods exist in the JDK. For example, List.add() is optional. Implementations must throw an UnsupportedOperationException if they don't want to implement this method.

If you want to be able to know if the optional method is implemented or not, then you could add another method (not optional) :

/**
 * Returns true if optionalOperation() is supported and implemented, false otherwise
 */
boolean isOptionalOperationSupported();

/**
 * implements he foobar operation. Optional. If not supported, this method must throw
 * UnsupportedOperationException, and isOptionalOperationSupported() must return false.
 */
void optionalOperation();