parser.java

来自「Zuul经典Java迷宫游戏.但是只是实现基本行走,拾取,放下,和与npc交易.」· Java 代码 · 共 72 行

import java.util.Scanner;

/**
 * This class is part of the "World of Zuul" application. 
 * "World of Zuul" is a very simple, text based adventure game.  
 *
 * This parser reads user input and tries to interpret it as an "Adventure"
 * command. Every time it is called it reads a line from the terminal and
 * tries to interpret the line as a two word command. It returns the command
 * as an object of class Command.
 *
 * The parser has a set of known command words. It checks user input against
 * the known commands, and if the input is not one of the known commands, it
 * returns a command object that is marked as an unknown command.
 * 
 * @author  Michael Kolling and David J. Barnes
 * @version 2004.12.07
 */
public class Parser 
{
    private CommandWords commands;  // holds all valid command words
    private Scanner reader;         // returns user input.

    /**
     * Create a Parser for reading user input.
     */
    public Parser() 
    {
        commands = new CommandWords();
        // Scan standard input.
        reader = new Scanner(System.in);
    }

    /**
     * Parse the next user command.
     * @return The user's command.
     */
    public Command getCommand() 
    {
        String inputLine = "";   // will hold the full input line
        String word1;
        String word2;

        System.out.print("> ");     // print prompt

        String line = reader.nextLine();
        Scanner scan = new Scanner(line);
        
        if(scan.hasNext())
            word1 = scan.next();      // get first word
        else
            word1 = null;
        if(scan.hasNext())
            word2 = scan.next();      // get second word
        else
            word2 = null;

        // note: we just ignore the rest of the input line.

        // Create a command with it.
        return new Command(word1, word2);
    }

    /**
     * Print out a list of valid command words.
     */
    public void showCommands()
    {
        commands.showAll();
    }
}