added backspace support and basic error checking in settings and gui. 2 major bugs: empty cells always start in note mode, and the sizing is not constant.

src/gui/Board.java

@@ -1,5 +1,6 @@
 package gui;
 
+import java.awt.Dimension;
 import java.awt.GridLayout;
 import java.awt.LayoutManager;
 import java.awt.event.KeyAdapter;
@@ -29,6 +30,7 @@ import gui.backend.SudokuChecker;
 public class Board extends JPanel {
     private Settings s;
     private Cell[][] grid;
+    private Cell[][] solvedGrid;
     private CellGUI[][] gridGUI;
     private SudokuChecker sc;
     private CellGUI selected;
@@ -43,6 +45,8 @@ public class Board extends JPanel {
         this.s = s;
         this.grid = grid;
         this.sc = sc;
+        solvedGrid = new SudokuChecker(Cell.copyGrid(grid)).getSolution();
+
         style();
         createBoard();
     }
@@ -50,30 +54,42 @@ public class Board extends JPanel {
     private KeyListener createKeyListener() {
         return new KeyListener() {
             @Override
-            public void keyTyped(KeyEvent e) {
+            public void keyTyped(KeyEvent e) {}
-                char key = e.getKeyChar();
-                if(!Character.isDigit(key)) return;
-                if(selected.cell.isInitValue()) return;
-
-                if(e.getKeyCode() == e.VK_BACK_SPACE) {
-                    if(selected.isInNotesMode()) {
-                        System.out.println("Remove all notes.");
-                        return;
-                    } else {
-                        selected.setValue(0);
-                        return;
-                    }
-                }
-
-                if(!selected.isInNotesMode())
-                    selected.setValue(Character.getNumericValue(key));
-            }
 
             @Override
             public void keyPressed(KeyEvent e) {}
 
             @Override
-            public void keyReleased(KeyEvent e) {}
+            public void keyReleased(KeyEvent e) {
+                char key = e.getKeyChar();
+                if(selected.cell.isInitValue()) return;
+                
+                // Backspace key code is 0
+                if(e.getKeyCode() == e.VK_BACK_SPACE) {
+                    selected.removeValue();
+                    selected.repaint();
+                    selected.revalidate();
+                    return;
+                }
+
+                if(!Character.isDigit(key)) return;
+
+                if(!selected.isInNotesMode()) {
+                    if(s.getAutoCheckValues()) {
+                        int row = selected.cell.getRow();
+                        int col = selected.cell.getCol();
+                        int expected = solvedGrid[row][col].getValue();
+                        selected.setValue(Character.getNumericValue(key), expected);
+                    } else {
+                        selected.setValue(Character.getNumericValue(key));
+                    }
+                } else {
+                    selected.addPossibleValue(Character.getNumericValue(key));
+                }
+
+                selected.repaint();
+                selected.revalidate();
+            }
         };
     }
 
@@ -171,7 +187,8 @@ public class Board extends JPanel {
                 CellGUI cell = new CellGUI(
                     grid[i][j],
                     s.getCellGUIStartMode(),
-                    s.getTheme()
+                    s.getTheme(),
+                    s.getCellDimensions()
                 );
                 cell.addMouseListener(new MouseListener() {
                     @Override

src/gui/CellGUI.java

@@ -1,6 +1,7 @@
 package gui;
 
 import java.awt.BorderLayout;
+import java.awt.Dimension;
 import java.awt.GridLayout;
 
 import javax.swing.JLabel;
@@ -19,9 +20,11 @@ class CellGUI extends JPanel {
     private JPanel internalPanel = new JPanel(new BorderLayout());
         private GridLayout noteLayout = new GridLayout(3, 3);
         private GridLayout valueLayout = new GridLayout(0, 1);
+        private Dimension size;
     private JLabel valueLabel;
     private Note[] notesLabels = new Note[9];
     private Theme theme;
+    private boolean incorrect;
 
     // Data fields
     Cell cell;
@@ -36,7 +39,7 @@ class CellGUI extends JPanel {
      * @param cell
      * @param startInNotesOrValueMode
      */
-    public CellGUI(Cell cell, boolean noteMode, Theme theme) {
+    public CellGUI(Cell cell, boolean noteMode, Theme theme, Dimension size) {
         super();
         this.cell = cell;
         this.noteMode = !noteMode; // Flip for use with setNoteMode()
@@ -45,7 +48,9 @@ class CellGUI extends JPanel {
         setFocusable(true);
         setLayout(valueLayout);
         valueLabel = new JLabel("", SwingConstants.CENTER);
-        style();
+        this.size = size;
+        setSize(this.size);
+        defaultStyle();
 
         // Populate the cell with the appropriate value or notes.
         if(cell.getValue() == 0) {
@@ -59,6 +64,25 @@ class CellGUI extends JPanel {
         add(internalPanel);
     }
 
+    /**
+     * Get the size of the cell.
+     */
+    public Dimension getSize() {
+        return size;
+    }
+
+    /**
+     * Set the size of the cell.
+     */
+    public void setSize(Dimension size) {
+        this.size = size;
+        super.setSize(size);
+        internalPanel.setSize(size);
+        valueLabel.setSize(size);
+        for(int i = 0; i < 9; i++)
+            if(notesLabels[i] != null) notesLabels[i].setSize(size);
+    }
+
     /**
      * Get the value of the underlying Cell object.
      * 
@@ -81,6 +105,45 @@ class CellGUI extends JPanel {
         internalPanel.revalidate();
     }
 
+    /**
+     * Set the value of the underlying Cell object.
+     * 
+     * This implementation allows for incorrect values to be highlighted.
+     * 
+     * @param value
+     */
+    public void setValue(int value, int expected) {
+        if(!selected) return;
+
+        cell.setValue(value);
+        valueLabel.setText(Integer.toString(cell.getValue()));
+
+        if(value != expected) {
+            incorrect = true;
+            errorStyle();
+        }
+
+        internalPanel.repaint();
+        internalPanel.revalidate();
+    }
+
+    /**
+     * Remove the value of the underlying Cell object.
+     */
+    public void removeValue() {
+        if(!selected) return;
+
+        cell.setValue(0);
+        if(!cell.isInitValue())
+            valueLabel.setText("");
+
+        incorrect = false;
+        highlightedStyle();
+
+        internalPanel.repaint();
+        internalPanel.revalidate();
+    }
+
     /**
      * Set the possible values of the underlying Cell object.
      * 
@@ -96,8 +159,13 @@ class CellGUI extends JPanel {
      * @param value
      */
     public void addPossibleValue(int value) {
+        if(!selected) return;
+
         cell.addPossibleValue(value);
-        setNoteMode();
+        internalPanel.removeAll();
+        internalPanel.setLayout(noteLayout);
+        generateNotes();
+        highlightedStyle();
     }
 
     /**
@@ -155,10 +223,45 @@ class CellGUI extends JPanel {
 
     public void select() {
         selected = !selected;
+        if(incorrect) {
+            errorStyle();
+            repaint();
+            revalidate();
+            return;
+        }
 
-        if(!selected) {
+        if(!selected)
-            style();
+            defaultStyle();
-        } else {
+
+        else highlightedStyle();
+        
+        repaint();
+        revalidate();
+    }
+
+    /**
+     * Style the cell with the appropriate colors from the theme.
+     */
+    private void defaultStyle() {
+        setBackground(theme.getPrimaryBackground());
+        setForeground(theme.getPrimaryText());
+        internalPanel.setBackground(theme.getPrimaryBackground());
+        internalPanel.setForeground(theme.getPrimaryText());
+        valueLabel.setForeground(theme.getPrimaryText());
+        setBorder(new LineBorder(theme.getPrimaryBorder(), 2));
+
+        for(int i = 0; i < 9; i++) {
+            if(notesLabels[i] != null) {
+                notesLabels[i].setBackground(theme.getPrimaryBackground());
+                notesLabels[i].setForeground(theme.getPrimaryText());
+            }
+        }
+    }
+
+    /**
+     * Style the cell with the appropriate colors from the theme.
+     */
+    private void highlightedStyle() {
         setBackground(theme.getSecondaryBackground());
         setForeground(theme.getSecondaryText());
         internalPanel.setBackground(theme.getSecondaryBackground());
@@ -174,25 +277,21 @@ class CellGUI extends JPanel {
         }
     }
 
-        repaint();
-        revalidate();
-    }
-
     /**
      * Style the cell with the appropriate colors from the theme.
      */
-    private void style() {
+    private void errorStyle() {
-        setBackground(theme.getPrimaryBackground());
+        setBackground(theme.getErrorBackground());
-        setForeground(theme.getPrimaryText());
+        setForeground(theme.getErrorText());
-        internalPanel.setBackground(theme.getPrimaryBackground());
+        internalPanel.setBackground(theme.getErrorBackground());
-        internalPanel.setForeground(theme.getPrimaryText());
+        internalPanel.setForeground(theme.getErrorText());
-        valueLabel.setForeground(theme.getPrimaryText());
+        valueLabel.setForeground(theme.getErrorText());
-        setBorder(new LineBorder(theme.getPrimaryBorder(), 2));
+        setBorder(new LineBorder(theme.getErrorBorder(), 2));
 
         for(int i = 0; i < 9; i++) {
             if(notesLabels[i] != null) {
-                notesLabels[i].setBackground(theme.getPrimaryBackground());
+                notesLabels[i].setBackground(theme.getErrorBackground());
-                notesLabels[i].setForeground(theme.getPrimaryText());
+                notesLabels[i].setForeground(theme.getErrorText());
             }
         }
     }

src/gui/backend/Cell.java

@@ -126,6 +126,7 @@ public class Cell {
         if(initValue) return;
 
         if(possibleValues.contains(value)) {
+            removePossibleValue(value);
             return;
         } else if(value < 1 || value > 9) {
             return;
@@ -181,6 +182,17 @@ public class Cell {
         return initValue;
     }
 
+    public static Cell[][] copyGrid(Cell[][] grid) {
+        Cell[][] newGrid = new Cell[9][9];
+        for(int row = 0; row < 9; row++) {
+            for(int col = 0; col < 9; col++) {
+                newGrid[row][col] = new Cell(row, col, grid[row][col].getValue());
+            }
+        }
+
+        return newGrid;
+    }
+
     /**
      * Given the cell's row and column, set the box number for the cell.
      */

src/gui/backend/Settings.java

@@ -41,6 +41,9 @@ public class Settings {
     // The default dimension of the application window.
     private Dimension dimension;
 
+    // The default dimension of the cells in the application window.
+    private Dimension cellDimension;
+
     // Resizable setting
     private boolean resizable;
 
@@ -56,6 +59,9 @@ public class Settings {
     // Auto-fill notes
     private boolean autoFillNotes;
 
+    // Auto check values
+    private boolean autoCheckValues;
+
     /**
      * Create a new Settings object, initializing the default settings
      * or reading in the settings from settings file if it exists.
@@ -310,6 +316,53 @@ public class Settings {
         updateSettingsFile();
     }
 
+    /**
+     * The Auto-check values setting is a configurable setting, where the user
+     * can specify whether values should be automatically checked when placed
+     * in a cell.
+     * 
+     * By default, the auto-check values setting is set to false.
+     * 
+     * @return
+     */
+    public boolean getAutoCheckValues() {
+        return autoCheckValues;
+    }
+
+    /**
+     * Set the auto-check values setting and write it to the settings file.
+     * 
+     * @param autoCheckValues
+     */
+    public void setAutoCheckValues(boolean autoCheckValues) {
+        this.autoCheckValues = autoCheckValues;
+        updateSettingsFile();
+    }
+
+    /**
+     * The default dimensions of the cells in the application window.
+     * 
+     * The default dimensions are set to 50x50 pixels.
+     * 
+     * @return
+     */
+    public Dimension getCellDimensions() {
+        return cellDimension;
+    }
+
+    private void setCellDimensions() {
+        int height;
+        int width;
+
+        if(dimension.height < 500) height = 50;
+        else height = dimension.height / 10;
+
+        if(dimension.width < 500) width = 50;
+        else width = dimension.width / 10;
+
+        cellDimension = new Dimension(width, height);
+    }
+
     /**
      * Open and write the settings to the settings file.
      * 
@@ -346,7 +399,9 @@ public class Settings {
         cellGUIStartMode = false;
         defaultOpenState = 0;
         theme = new Theme(new File(appDirectory + "default.theme"));
-        autoFillNotes = true;
+        autoFillNotes = false;
+        autoCheckValues = true;
+        setCellDimensions();
 
         updateSettingsFile();
     }

src/gui/backend/Theme.java

@@ -32,6 +32,8 @@ import java.io.File;
  * It provides colors for various GUI elements.
  */
 public class Theme {
+    private File theme;
+
     private Color primaryBackground;
     private Color secondaryBackground;
     private Color primaryText;
@@ -46,6 +48,9 @@ public class Theme {
     private Color secondaryButtonHighlight;
     private Color primaryButtonBorder;
     private Color secondaryButtonBorder;
+    private Color errorBackground;
+    private Color errorText;
+    private Color errorBorder;
 
     /**
      * Constructs a new Theme object with the given theme file.
@@ -77,6 +82,9 @@ public class Theme {
         secondaryText = Color.decode("#4A245E");
         primaryBorder = Color.decode("#A76BCA");
         secondaryBorder = Color.decode("#DBABF7");
+        errorBackground = Color.decode("#FF0000");
+        errorText = Color.decode("#FFFFFF");
+        errorBorder = Color.decode("#FF0000");
     }
 
     /**
@@ -331,5 +339,57 @@ public class Theme {
         this.secondaryButtonBorder = secondaryButtonBorder;
     }
 
-    private File theme;
+    /**
+     * Gets the error background color.
+     *
+     * @return the error background color
+     */
+    public Color getErrorBackground() {
+        return errorBackground;
+    }
+
+    /**
+     * Sets the error background color.
+     *
+     * @param errorBackground the error background color
+     */
+    public void setErrorBackground(Color errorBackground) {
+        this.errorBackground = errorBackground;
+    }
+
+    /**
+     * Gets the error text color.
+     *
+     * @return the error text color
+     */
+    public Color getErrorText() {
+        return errorText;
+    }
+
+    /**
+     * Sets the error text color.
+     *
+     * @param errorText the error text color
+     */
+    public void setErrorText(Color errorText) {
+        this.errorText = errorText;
+    }
+
+    /**
+     * Gets the error border color.
+     *
+     * @return the error border color
+     */
+    public Color getErrorBorder() {
+        return errorBorder;
+    }
+
+    /**
+     * Sets the error border color.
+     *
+     * @param errorBorder the error border color
+     */
+    public void setErrorBorder(Color errorBorder) {
+        this.errorBorder = errorBorder;
+    }
 }