net.markenwerk.commons.interfaces

Interface Handler<Value>

Type Parameters:

Value - The type of the involved values.

public interface Handler<Value>

For an arbitrary process, that may encounter some condition and needs to delegate the handling, a Handler is used, to convey the involved value from the executor of the process (hereafter: executor) back to the initiator of the process (hereafter: initiator).

Depending on the concrete scenario, the initiator may reuse the same instance of Handler for multiple processes and even for the same executor.

The executor may or may not call handle(Object).

A useful application to this rule is, when the executor can ensure, that the result wont't be needed by the initiator, because the initiator itself is not needed anymore. This is usually implemented by placing the Callback in a WeakReference. Because using anonymous instances of Handler will most likely fail in this situation, it should be noted in the contract of the method, that takes the Handler as an argument.

The executor may call handle(Object), more than once, depending o the concrete scenario, to convey partial or updated results. This should be noted in the contract of the method, that is used to convey the Handler to the executor.

The executor must not call handle(Object) more than once for the same subject.

Since:

4.0.0

Author:

Torsten Krause (tk at markenwerk dot net)

Method Summary

Modifier and Type	Method and Description
void	handle(Value value) Called by the executor when an condition occurs.

Method Detail

handle

void handle(Value value)
     throws HandlingException

Called by the executor when an condition occurs.

Implementers should catch any exception and wrap them in a HandlingException.

Parameters:

value - The involved value.

Throws:

HandlingException - If the handling failed.