Sunday, 9 February 2014

Command Design pattern - Implementation [Menu]



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Command Design pattern - Implementation [Menu]

Command Design pattern - Implementation [Menu]
Command Design pattern - Implementation [Menu] - Class Diagram

WordDocument.java

/*
 *  Receiver
 */

public class WordDocument
{
public void open()
{
System.out.println("Document Opened");
}

public void save()
{
System.out.println("Document Saved");
}

public void close()
{
System.out.println("Document Closed");
}

}

Command.java

public interface Command
{
public void execute();
}

OpenCommand.java

public class OpenCommand implements Command
{
private WordDocument wordDocument;

public OpenCommand( WordDocument wordDocument )
{
this.wordDocument = wordDocument;
}

@Override
public void execute()
{
wordDocument.open();
}
}

SaveCommand.java

public class SaveCommand implements Command
{

private WordDocument wordDocument;

public SaveCommand( WordDocument wordDocument )
{
this.wordDocument = wordDocument;
}

@Override
public void execute()
{
wordDocument.save();
}
}


CloseCommand.java

public class CloseCommand implements Command
{
private WordDocument wordDocument;

public CloseCommand( WordDocument wordDocument )
{
this.wordDocument = wordDocument;
}

@Override
public void execute()
{
wordDocument.close();
}
}


MenuOptions.java

/*
 *  Invoker
 */

public class MenuOptions
{
private Command openCommand;
private Command saveCommand;
private Command closeCommand;

public MenuOptions( Command open, Command save, Command close )
{
this.openCommand = open;
this.saveCommand = save;
this.closeCommand = close;
}

public void clickOpen()
{
openCommand.execute();
}

public void clickSave()
{
saveCommand.execute();
}

public void clickClose()
{
closeCommand.execute();
}
}

Client.java

public class Client
{
public static void main( String[] args )
{
WordDocument wordDocument = new WordDocument();
Command openCommand = new OpenCommand(wordDocument);
Command saveCommand = new SaveCommand(wordDocument);
Command closeCommand = new CloseCommand(wordDocument);
MenuOptions menu = new MenuOptions(openCommand, saveCommand, closeCommand);
menu.clickOpen();
menu.clickSave();
menu.clickClose();
}

}

Output

Document Opened
Document Saved
Document Closed

See also:

  • Command Design pattern - Introduction
  • Command Design pattern - Real time example [Hotel]
  • Command Design pattern - Real time example [Menu]
  • Command Design pattern - Class Diagram
  • Command Design pattern - Sequence Diagram
  • Command Design pattern - Object Creation and flow
  • Command Design pattern - Key points
  • All Design Patterns Links
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