import java.util.HashMap;/** * This class is part of the "World of Zuul" application.  * "World of Zuul" is a very simple, text based adventure game. *  * This class holds an enumeration of all command words known to the game. * It is used to recognise commands as they are typed in. * * @author  Michael Kolling and David J. Barnes * @version 2006.03.30 */public class CommandWords{    // A mapping between a command word and the CommandWord    // associated with it.    private HashMap<String, CommandWord> validCommands;    /**     * Constructor - initialise the command words.     */    public CommandWords()    {        validCommands = new HashMap<String, CommandWord>();        for(CommandWord command : CommandWord.values()) {            if(command != CommandWord.UNKNOWN) {                validCommands.put(command.toString(), command);            }        }    }    /**     * Find the CommandWord associated with a command word.     * @param commandWord The word to look up.     * @return The CommandWord correspondng to commandWord, or UNKNOWN     *         if it is not a valid command word.     */    public CommandWord getCommandWord(String commandWord)    {        CommandWord command = validCommands.get(commandWord);        if(command != null) {            return command;        }        else {            return CommandWord.UNKNOWN;        }    }        /**     * Check whether a given String is a valid command word.      * @return true if it is, false if it isn't.     */    public boolean isCommand(String aString)    {        return validCommands.containsKey(aString);    }    /**     * Print all valid commands to System.out.     */    public void showAll()     {        for(String command : validCommands.keySet()) {            System.out.print(command + "  ");        }        System.out.println();    }}