LongListTest.java Source code

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Here is the source code for LongListTest.java

Source

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)
    
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
    
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
    
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;

import javax.swing.AbstractListModel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.ListSelectionModel;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

/**
 * This program demonstrates a list that dynamically computes list entries.
 * @version 1.23 2007-08-01
 * @author Cay Horstmann
 */
public class LongListTest {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new LongListFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}

/**
 * This frame contains a long word list and a label that shows a sentence made up from the chosen
 * word.
 */
class LongListFrame extends JFrame {
    public LongListFrame() {
        setTitle("LongListTest");
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

        wordList = new JList(new WordListModel(3));
        wordList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        wordList.setPrototypeCellValue("www");
        JScrollPane scrollPane = new JScrollPane(wordList);

        JPanel p = new JPanel();
        p.add(scrollPane);
        wordList.addListSelectionListener(new ListSelectionListener() {
            public void valueChanged(ListSelectionEvent evt) {
                StringBuilder word = (StringBuilder) wordList.getSelectedValue();
                setSubject(word.toString());
            }

        });

        Container contentPane = getContentPane();
        contentPane.add(p, BorderLayout.NORTH);
        label = new JLabel(prefix + suffix);
        contentPane.add(label, BorderLayout.CENTER);
        setSubject("fox");
    }

    /**
     * Sets the subject in the label.
     * @param word the new subject that jumps over the lazy dog
     */
    public void setSubject(String word) {
        StringBuilder text = new StringBuilder(prefix);
        text.append(word);
        text.append(suffix);
        label.setText(text.toString());
    }

    private static final int DEFAULT_WIDTH = 400;
    private static final int DEFAULT_HEIGHT = 300;
    private JList wordList;
    private JLabel label;
    private String prefix = "The quick brown ";
    private String suffix = " jumps over the lazy dog.";
}

/**
 * A model that dynamically generates n-letter words.
 */
class WordListModel extends AbstractListModel {
    /**
     * Constructs the model.
     * @param n the word length
     */
    public WordListModel(int n) {
        length = n;
    }

    public int getSize() {
        return (int) Math.pow(LAST - FIRST + 1, length);
    }

    public Object getElementAt(int n) {
        StringBuilder r = new StringBuilder();
        ;
        for (int i = 0; i < length; i++) {
            char c = (char) (FIRST + n % (LAST - FIRST + 1));
            r.insert(0, c);
            n = n / (LAST - FIRST + 1);
        }
        return r;
    }

    private int length;
    public static final char FIRST = 'a';
    public static final char LAST = 'z';
}