org.perfectjpattern.core.api.behavioral.command
Interface ICommand<P,R>

Type Parameters:

P - Command Parameter context-specific

R - Command Result context-specific

All Known Subinterfaces:

IParameterlessCommand

All Known Implementing Classes:

Command, ParameterlessCommand

public interface ICommand<P,R>

Command Design Pattern: Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations. (Gamma et al, Design Patterns)

Responsibility: Abstract generic definition of the "Command".

• Declares an interface for executing an operation.

Example usage:

    //
    // Create Command Pattern elements 
    //  
    IInvoker myInvoker = new ConcreteInvoker();
    ICommand myCommand = new ConcreteCommand();
    IReceiver myReceiver = new ConcreteReceiver();
    
    //
    // Associate Command Pattern elements 
    //
    myInvoker.setCommand(myCommand);
    myCommand.setReceiver(myReceiver);
    
    //
    // Optionally parameterize the Invoker
    //
    myInvoker.setParameter(new SomeParameter());
    
    //
    // Execute Invoker's invoke method that triggers execution of 
    // Command and Receiver
    //
    myInvoker.invoke();
    
    //
    // Optionally and if the Command is synchronous, retrieve a result
    //
    System.out.println(myInvoker.getResult().toString());
 

Version:

$Revision: 1.0 $ $Date: Jun 19, 2007 11:09:51 PM $

Author:

Giovanni Azua

Method Summary

void	execute() Executes the ICommand.
R	getResult() Returns the result of this ICommand execution.
void	setParameter(P aParameter) Sets the parameter required for the execution of the target IReceiver.
void	setReceiver(IReceiver<P,R> aReceiver) Sets the IReceiver associated to this ICommand

Method Detail

getResult

R getResult()
            throws IllegalStateException

Returns the result of this ICommand execution.

Returns:

Result of this ICommand execution.

Throws:

IllegalStateException - IReceiver was not set.

IllegalStateException - No result available.

setParameter

void setParameter(P aParameter)
                  throws IllegalArgumentException

Sets the parameter required for the execution of the target IReceiver.

Parameters:

aParameter - Parameter required for the execution of the target IReceiver.

Throws:

IllegalArgumentException - 'aParameter' must not be null.

setReceiver

void setReceiver(IReceiver<P,R> aReceiver)
                 throws IllegalArgumentException

Sets the IReceiver associated to this ICommand

Parameters:

aReceiver - to set

Throws:

IllegalArgumentException - 'aReceiver' must not be null.

execute

void execute()
             throws IllegalStateException

Executes the ICommand.

Throws:

IllegalStateException - IReceiver was not set.