Java Design Patterns Command Patterns

interface Command {
   void doCommand();
}

class MyUndoCommand implements Command {
   private Receiver receiver;

   MyUndoCommand(Receiver recv) {
      receiver = recv;//from  ww w  .ja v  a2  s  .co  m
   }

   @Override
   public void doCommand() {
      receiver.performUndo();
   }
}

class MyRedoCommand implements Command {
   private Receiver receiver;

   MyRedoCommand(Receiver recv) {
      receiver = recv;
   }

   @Override
   public void doCommand() {
      receiver.performRedo();
   }
}

class Receiver {
   public void performUndo() {
      System.out.println("Undo Command");
   }

   public void performRedo() {
      System.out.println("Redo Command");
   }
}

class Invoke {
   Command cmd;

   public void executeCommand(Command cmd) {
      this.cmd = cmd;
      this.cmd.doCommand();
   }
}

public class Main {
   public static void main(String[] args) {
      Receiver editor = new Receiver();

      Invoke inv = new Invoke();
      MyUndoCommand unCmd = new MyUndoCommand(editor);
      MyRedoCommand reCmd = new MyRedoCommand(editor);
      
      inv.executeCommand(unCmd);
      inv.executeCommand(reCmd);
   }
}