001package myhw3.command;
002
003/**
004 * An UndoableCommand may be run at most once.
005 */
006public interface Command {
007        /**
008         * Do the command.
009         * @return true if command succeeds, false otherwise
010         */
011        public boolean run ();
012        /**
013         * Undo the command.
014         */
015        public void undo ();
016        /**
017         * Redo the command.
018         */
019        public void redo ();
020}