wicket-examples/src/java/wicket/examples/hangman/WordGenerator.java

/*
 * $Id$ $Revision:
 * 1.2 $ $Date$
 * 
 * ==================================================================== Licensed
 * under the Apache License, Version 2.0 (the "License"); you may not use this
 * file except in compliance with the License. You may obtain a copy of the
 * License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package wicket.examples.hangman;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.LineNumberReader;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import java.util.Collections;

/**
 * The word generator is responsible for reading in a list of words from a data
 * file and serving them up in a random order. The generator keeps a state
 * record of which words it has served and randomises them again when the last
 * word has been served.
 * 
 * @author Chris Turner
 * @version 1.0
 */
public class WordGenerator implements Serializable
{
	/**
	 * Comment for <code>serialVersionUID</code>
	 */
	private static final long serialVersionUID = 1L;

	private static final String WORD_LIST_RESOURCE = "wicket/examples/hangman/WordList.txt";

	private List words;
	private int index;

	/**
	 * Create the word generator, loading the words and preparing them for
	 * serving.
	 * 
	 * @throws WordListException
	 *             If the word list cannot be loaded
	 */
	public WordGenerator() throws WordListException
	{
		loadWords();
		randomiseWords();
	}

	/**
	 * Create the word generator using the supplied array of words as the word
	 * source to use.
	 * 
	 * @param words
	 *            The words to use
	 */
	public WordGenerator(final String[] words)
	{
		this.words = new ArrayList(words.length);
		for (int i = 0; i < words.length; i++)
		{
			this.words.add(words[i].toLowerCase());
		}
		randomiseWords();
	}

	/**
	 * Returns the next word from the word generator.
	 * 
	 * @return The next word
	 */
	public String nextWord()
	{
		String word = (String)words.get(index);
		index++;
		if (index == words.size())
			randomiseWords();
		return word;
	}

	/**
	 * Get the number of words that were discovered.
	 * 
	 * @return The number of words
	 */
	public int getWordCount()
	{
		return words.size();
	}

	/**
	 * Load the words from the data file into the internal word list.
	 * 
	 * @throws WordListException
	 *             If the word list cannot be read
	 */
	private void loadWords() throws WordListException
	{
		InputStream iStream = getClass().getClassLoader().getResourceAsStream(WORD_LIST_RESOURCE);
		if (iStream == null)
		{
			throw new WordListException("Unable to find word list resource: " + WORD_LIST_RESOURCE);
		}
		LineNumberReader reader = new LineNumberReader(new InputStreamReader(iStream));
		String line;
		words = new ArrayList();
		try
		{
			while ((line = reader.readLine()) != null)
			{
				line = line.trim().toLowerCase();
				if (line.length() > 0)
					words.add(line);
			}
			reader.close();
		}
		catch (IOException e)
		{
			throw new WordListException("Error reading word list resource: " + WORD_LIST_RESOURCE,
					e);
		}
	}

	/**
	 * Randomises the list of loaded words and sets the index back to the
	 * beginning of the word list.
	 */
	private void randomiseWords()
	{
		Collections.shuffle(words);
		index = 0;
	}
}