Changing cell implementation

AllenDowney · AllenDowney · commit da0053babfca · 2019-09-25T10:07:44.000-04:00
diff --git a/ch15/Cell.java b/ch15/Cell.java
@@ -6,13 +6,12 @@
  */
 public class Cell {
 
-    public static final Color OFF = Color.WHITE;
-    public static final Color ON = Color.BLACK;
+	public static final Color colors[] = {Color.WHITE, Color.BLACK};
 
     private final int x;
     private final int y;
     private final int size;
-    private Color color;
+    private int state;
 
     /**
      * Constructs a new cell, initially turned off.
@@ -25,7 +24,7 @@ public Cell(int x, int y, int size) {
         this.x = x;
         this.y = y;
         this.size = size;
-        this.color = OFF;
+        this.state = 0;
     }
 
     /**
@@ -34,38 +33,38 @@ public Cell(int x, int y, int size) {
      * @param g graphics context
      */
     public void draw(Graphics g) {
-        g.setColor(this.color);
+    	Color color = colors[this.state];
+        g.setColor(color);
         g.fillRect(x + 1, y + 1, size - 1, size - 1);
         g.setColor(Color.LIGHT_GRAY);
         g.drawRect(x, y, size, size);
     }
 
     /**
-     * @return true if the color is OFF
+     * @return true if the cell is OFF
      */
     public boolean isOff() {
-        return color == OFF;
+        return state == 0;
     }
 
     /**
-     * @return true if the color is ON
+     * @return true if the cell is ON
      */
     public boolean isOn() {
-        return color == ON;
+        return state == 1;
     }
 
     /**
-     * Sets the cell's color to OFF.
+     * Sets the cell's state to OFF.
      */
     public void turnOff() {
-        color = OFF;
+        state = 0;
     }
 
     /**
-     * Sets the cell's color to ON.
+     * Sets the cell's state to ON.
      */
     public void turnOn() {
-        color = ON;
+        state = 1;
     }
-
 }
diff --git a/ch15/Conway.java b/ch15/Conway.java
@@ -13,14 +13,14 @@ public class Conway extends Automaton {
      */
     public Conway() {
         grid = new GridCanvas(30, 25, SIZE);
-        grid.init(1, 2);
-        grid.init(2, 2);
-        grid.init(3, 2);
-        grid.init(6, 1);
-        grid.init(7, 2);
-        grid.init(7, 3);
-        grid.init(8, 1);
-        grid.init(8, 2);
+        grid.turnCellOn(1, 2);
+        grid.turnCellOn(2, 2);
+        grid.turnCellOn(3, 2);
+        grid.turnCellOn(6, 1);
+        grid.turnCellOn(7, 2);
+        grid.turnCellOn(7, 3);
+        grid.turnCellOn(8, 1);
+        grid.turnCellOn(8, 2);
     }
 
     /**
@@ -71,7 +71,7 @@ public Conway(String path, int margin) {
             for (int c = 0; c < line.length(); c++) {
                 char x = line.charAt(c);
                 if (x == 'O') {
-                    grid.init(r + margin, c + margin);
+                	grid.getCell(r + margin, c + margin).turnOn();
                 }
             }
         }
@@ -139,7 +139,7 @@ public void update() {
         // update each cell based on neighbor counts
         for (int r = 0; r < rows; r++) {
             for (int c = 0; c < cols; c++) {
-                Cell cell = grid.cellAt(r, c);
+                Cell cell = grid.getCell(r, c);
                 updateCell(cell, counts[r][c]);
             }
         }
diff --git a/ch15/GridCanvas.java b/ch15/GridCanvas.java
@@ -51,7 +51,7 @@ public int numCols() {
      * @param c column index
      * @return the cell
      */
-    public Cell cellAt(int r, int c) {
+    public Cell getCell(int r, int c) {
         return array[r][c];
     }
 
@@ -61,7 +61,7 @@ public Cell cellAt(int r, int c) {
      * @param r row index
      * @param c column index
      */
-    public void init(int r, int c) {
+    public void turnCellOn(int r, int c) {
         array[r][c].turnOn();
     }
 
diff --git a/ch15/Langton.java b/ch15/Langton.java
@@ -25,7 +25,7 @@ public Langton(int rows, int cols) {
      */
     public void update() {
 
-        Cell cell = grid.cellAt(xpos, ypos);
+        Cell cell = grid.getCell(xpos, ypos);
         if (cell.isOff()) {
             // at a white square; turn right and flip color
             head = (head + 1) % 4;
