Sudoku Graphical User Interface

ButtonPanel.java

package nl.elridge.sudoku.view;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.util.Observable;
import java.util.Observer;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JPanel;
import javax.swing.JToggleButton;
import nl.elridge.sudoku.controller.ButtonController;
import nl.elridge.sudoku.model.UpdateAction;

/**
 * This class draws the button panel and reacts to updates from the model.
 *
 * @author Eric Beijer
 */
public class ButtonPanel extends JPanel implements Observer {
    JButton btnNew, btnCheck, btnExit;   // Used buttons.
    JCheckBox cbHelp;               // Used check box.
    ButtonGroup bgNumbers;          // Group for grouping the toggle buttons.
    JToggleButton[] btnNumbers;     // Used toggle buttons.

    /**
     * Constructs the panel and arranges all components.
     */
    public ButtonPanel() {
        super(new BorderLayout());

        JPanel pnlAlign = new JPanel();
        pnlAlign.setLayout(new BoxLayout(pnlAlign, BoxLayout.PAGE_AXIS));
        add(pnlAlign, BorderLayout.NORTH);

        JPanel pnlOptions = new JPanel(new FlowLayout(FlowLayout.LEADING));
        pnlOptions.setBorder(BorderFactory.createTitledBorder(" Options "));
        pnlAlign.add(pnlOptions);

        btnNew = new JButton("New");
        btnNew.setFocusable(false);
        pnlOptions.add(btnNew);

        btnCheck = new JButton("Check");
        btnCheck.setFocusable(false);
        pnlOptions.add(btnCheck);

        btnExit = new JButton("Exit");
        btnExit.setFocusable(false);
        pnlOptions.add(btnExit);

        JPanel pnlNumbers = new JPanel();
        pnlNumbers.setLayout(new BoxLayout(pnlNumbers, BoxLayout.PAGE_AXIS));
        pnlNumbers.setBorder(BorderFactory.createTitledBorder(" Numbers "));
        pnlAlign.add(pnlNumbers);

        JPanel pnlNumbersHelp = new JPanel(new FlowLayout(FlowLayout.LEADING));
        pnlNumbers.add(pnlNumbersHelp);

        cbHelp = new JCheckBox("Help on", true);
        cbHelp.setFocusable(false);
        pnlNumbersHelp.add(cbHelp);

        JPanel pnlNumbersNumbers = new JPanel(new FlowLayout(FlowLayout.LEADING));
        pnlNumbers.add(pnlNumbersNumbers);

        bgNumbers = new ButtonGroup();
        btnNumbers = new JToggleButton[9];
        for (int i = 0; i < 9; i++) {
            btnNumbers[i] = new JToggleButton("" + (i + 1));
            btnNumbers[i].setPreferredSize(new Dimension(40, 40));
            btnNumbers[i].setFocusable(false);
            bgNumbers.add(btnNumbers[i]);
            pnlNumbersNumbers.add(btnNumbers[i]);
        }
    }

    /**
     * Method called when model sends update notification.
     *
     * @param o     The model.
     * @param arg   The UpdateAction.
     */
    public void update(Observable o, Object arg) {
        switch ((UpdateAction)arg) {
            case NEW_GAME:
            case CHECK:
                bgNumbers.clearSelection();
                break;
        }
    }

    /**
     * Adds controller to all components.
     *
     * @param buttonController  Controller which controls all user actions.
     */
    public void setController(ButtonController buttonController) {
        btnNew.addActionListener(buttonController);
        btnCheck.addActionListener(buttonController);
        btnExit.addActionListener(buttonController);
        cbHelp.addActionListener(buttonController);
        for (int i = 0; i < 9; i++)
            btnNumbers[i].addActionListener(buttonController);
    }
}

Field.java

package nl.elridge.sudoku.view;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import javax.swing.BorderFactory;
import javax.swing.JLabel;

/**
 * This class represents a field on the SudokuPanel.
 *
 * @author Eric Beijer
 */
public class Field extends JLabel {
    private int x;      // X position in game.
    private int y;      // Y position in game.

    /**
     * Constructs the label and sets x and y positions in game.
     *
     * @param x     X position in game.
     * @param y     Y position in game.
     */
    public Field(int x, int y) {
        super("", CENTER);
        this.x = x;
        this.y = y;
        
        setPreferredSize(new Dimension(40, 40));
        setBorder(BorderFactory.createLineBorder(Color.GRAY));
        setFont(new Font(Font.DIALOG, Font.PLAIN, 20));
        setOpaque(true);
    }

    /**
     * Sets number and foreground color according to userInput.
     *
     * @param number        Number to be set.
     * @param userInput     Boolean indicating number is user input or not.
     */
    public void setNumber(int number, boolean userInput) {
        setForeground(userInput ? Color.BLUE : Color.BLACK);
        setText(number > 0 ? number + "" : "");
    }

    /**
     * Returns x position in game.
     *
     * @return  X position in game.
     */
    public int getFieldX() {
        return x;
    }

    /**
     * Return y position in game.
     *
     * @return  Y position in game.
     */
    public int getFieldY() {
        return y;
    }
}

Sudoku.java

package nl.elridge.sudoku.view;

import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.UIManager;
import nl.elridge.sudoku.controller.ButtonController;
import nl.elridge.sudoku.controller.SudokuController;
import nl.elridge.sudoku.model.Game;

/**
 * Main class of program.
 *
 * @author Eric Beijer
 */
public class Sudoku extends JFrame {
    public Sudoku() {
        super("Sudoku");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        getContentPane().setLayout(new BorderLayout());

        Game game = new Game();

        ButtonController buttonController = new ButtonController(game);
        ButtonPanel buttonPanel = new ButtonPanel();
        buttonPanel.setController(buttonController);
        add(buttonPanel, BorderLayout.EAST);

        SudokuPanel sudokuPanel = new SudokuPanel();
        SudokuController sudokuController = new SudokuController(sudokuPanel, game);
        sudokuPanel.setGame(game);
        sudokuPanel.setController(sudokuController);
        add(sudokuPanel, BorderLayout.CENTER);

        game.addObserver(buttonPanel);
        game.addObserver(sudokuPanel);

        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    /**
     * Main entry point of program.
     * 
     * @param args Command line arguments.
     */
    public static void main(String[] args) {
        // Use System Look and Feel
        try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); }
        catch (Exception ex) { ex.printStackTrace(); }
        new Sudoku();
    }
}

SudokuPanel.java

package nl.elridge.sudoku.view;

import java.awt.Color;
import java.awt.GridLayout;
import java.util.Observable;
import java.util.Observer;
import javax.swing.BorderFactory;
import javax.swing.JPanel;
import nl.elridge.sudoku.controller.SudokuController;
import nl.elridge.sudoku.model.Game;
import nl.elridge.sudoku.model.UpdateAction;

/**
 * This class draws the sudoku panel and reacts to updates from the model.
 *
 * @author Eric Beijer
 */
public class SudokuPanel extends JPanel implements Observer {
    // Color constant for candidates.
    private static final Color COLOR_CANDIDATE = new Color(102, 153, 255);

    private Field[][] fields;       // Array of fields.
    private JPanel[][] panels;      // Panels holding the fields.

    /**
     * Constructs the panel, adds sub panels and adds fields to these sub panels.
     */
    public SudokuPanel() {
        super(new GridLayout(3, 3));

        panels = new JPanel[3][3];
        for (int y = 0; y < 3; y++) {
            for (int x = 0; x < 3; x++) {
                panels[y][x] = new JPanel(new GridLayout(3, 3));
                panels[y][x].setBorder(BorderFactory.createLineBorder(Color.DARK_GRAY));
                add(panels[y][x]);
            }
        }

        fields = new Field[9][9];
        for (int y = 0; y < 9; y++) {
            for (int x = 0; x < 9; x++) {
                fields[y][x] = new Field(x, y);
                panels[y / 3][x / 3].add(fields[y][x]);
            }
        }
    }

    /**
     * Method called when model sends update notification.
     *
     * @param o     The model.
     * @param arg   The UpdateAction.
     */
    public void update(Observable o, Object arg) {
        switch ((UpdateAction)arg) {
            case NEW_GAME:
                setGame((Game)o);
                break;
            case CHECK:
                setGameCheck((Game)o);
                break;
            case SELECTED_NUMBER:
            case CANDIDATES:
            case HELP:
                setCandidates((Game)o);
                break;
        }
    }

    /**
     * Sets the fields corresponding to given game.
     *
     * @param game  Game to be set.
     */
    public void setGame(Game game) {
        for (int y = 0; y < 9; y++) {
            for (int x = 0; x < 9; x++) {
                fields[y][x].setBackground(Color.WHITE);
                fields[y][x].setNumber(game.getNumber(x, y), false);
            }
        }
    }

    /**
     * Sets fields validity according to given game.
     *
     * @param game  Current game.
     */
    private void setGameCheck(Game game) {
        for (int y = 0; y < 9; y++) {
            for (int x = 0; x < 9; x++) {
                fields[y][x].setBackground(Color.WHITE);
                if (fields[y][x].getForeground().equals(Color.BLUE))
                    fields[y][x].setBackground(game.isCheckValid(x, y) ? Color.GREEN : Color.RED);
            }
        }
    }

    /**
     * Shows the candidates according to given game.
     *
     * @param game  Current game.
     */
    private void setCandidates(Game game) {
        for (int y = 0; y < 9; y++) {
            for (int x = 0; x < 9; x++) {
                fields[y][x].setBackground(Color.WHITE);
                if (game.isHelp() && game.isSelectedNumberCandidate(x, y))
                    fields[y][x].setBackground(COLOR_CANDIDATE);
            }
        }
    }

    /**
     * Adds controller to all sub panels.
     *
     * @param sudokuController  Controller which controls all user actions.
     */
    public void setController(SudokuController sudokuController) {
        for (int y = 0; y < 3; y++) {
            for (int x = 0; x < 3; x++)
                panels[y][x].addMouseListener(sudokuController);
        }
    }
}