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Semester 1/Programming 1/Java/examples/projects/chapter07/automaton-v3/Automaton.ctxt

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+#BlueJ class context
+comment0.params=numberOfCells
+comment0.target=Automaton(int)
+comment0.text=\n\ Create\ a\ 1D\ automaton\ consisting\ of\ the\ given\ number\ of\ cells.\n\ @param\ numberOfCells\ The\ number\ of\ cells\ in\ the\ automaton.\n
+comment1.params=
+comment1.target=void\ print()
+comment1.text=\n\ Print\ the\ current\ state\ of\ the\ automaton.\n
+comment2.params=
+comment2.target=void\ update()
+comment2.text=\n\ Update\ the\ automaton\ to\ its\ next\ state.\n
+comment3.params=
+comment3.target=void\ reset()
+comment3.text=\n\ Reset\ the\ automaton.\n
+comment4.params=left\ center\ right
+comment4.target=int\ calculateNextState(int,\ int,\ int)
+comment4.text=\n\ Calculate\ the\ next\ state\ of\ the\ center\ cell\n\ given\ current\ left,\ center\ and\ right\ cell\n\ values.\n\ This\ implements\ Wolfram\ code\ 110.\n\ @see\ https\://en.wikipedia.org/wiki/Wolfram_code\n\ @param\ left\ The\ state\ of\ the\ cell\ to\ the\ left\ of\ center.\n\ @param\ center\ The\ state\ of\ the\ center\ cell.\n\ @param\ right\ The\ state\ of\ the\ cell\ to\ the\ right\ of\ center.\n\ @return\ The\ new\ value\ of\ center\ (0\ or\ 1).\n
+numComments=5

Semester 1/Programming 1/Java/examples/projects/chapter07/automaton-v3/Automaton.java

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+import java.util.*;
+
+/**
+ * Model a 1D elementary cellular automaton.
+ * 
+ * @author David J. Barnes and Michael Kölling
+ * @version  2016.02.29 - version 3
+ */
+public class Automaton
+{
+    // The number of cells.
+    private final int numberOfCells;
+    // The state of the cells.
+    private int[] state;
+    
+    /**
+     * Create a 1D automaton consisting of the given number of cells.
+     * @param numberOfCells The number of cells in the automaton.
+     */
+    public Automaton(int numberOfCells)
+    {
+        this.numberOfCells = numberOfCells;
+        // Allow an extra element to avoid 'fencepost' errors.
+        state = new int[numberOfCells + 1];
+        // Seed the automaton with a single 'on' cell.
+        state[numberOfCells / 2] = 1;
+    }
+    
+    /**
+     * Print the current state of the automaton.
+     */
+    public void print()
+    {
+        for(int cellValue : state) {
+            System.out.print(cellValue == 1 ? "*" : " ");
+        }
+        System.out.println();
+    }   
+    
+    /**
+     * Update the automaton to its next state.
+     */
+    public void update()
+    {
+        // Build the new state in a separate array.
+        int[] nextState = new int[state.length];
+        // Use 0 for the non-existent value to the left of
+        // the first cell.
+        int left = 0;
+        int center = state[0];
+        for(int i = 0; i < numberOfCells; i++) {
+            int right = state[i + 1];
+            nextState[i] = calculateNextState(left, center, right);
+            left = center;
+            center = right;
+        }
+        state = nextState;
+    }
+    
+    /**
+     * Reset the automaton.
+     */
+    public void reset()
+    {
+        Arrays.fill(state, 0);
+        // Seed the automaton with a single 'on' cell in the middle.
+        state[numberOfCells / 2] = 1;
+    }
+
+    /**
+     * Calculate the next state of the center cell
+     * given current left, center and right cell
+     * values.
+     * This implements Wolfram code 110.
+     * @see https://en.wikipedia.org/wiki/Wolfram_code
+     * @param left The state of the cell to the left of center.
+     * @param center The state of the center cell.
+     * @param right The state of the cell to the right of center.
+     * @return The new value of center (0 or 1).
+     */
+    private int calculateNextState(int left, int center, int right)
+    {
+        return (center + right + center * right + left * center * right) % 2;
+    }
+
+}

Semester 1/Programming 1/Java/examples/projects/chapter07/automaton-v3/AutomatonController.ctxt

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+#BlueJ class context
+comment0.params=numberOfCells
+comment0.target=AutomatonController(int)
+comment0.text=\n\ Create\ an\ AutomatonController.\n\ @param\ numberOfCells\ The\ number\ of\ cells\ in\ the\ automaton.\n
+comment1.params=
+comment1.target=AutomatonController()
+comment1.text=\n\ Create\ an\ AutomatonController\ with\n\ a\ default\ number\ of\ cells.\n
+comment2.params=numSteps
+comment2.target=void\ run(int)
+comment2.text=\n\ Run\ the\ automaton\ for\ the\ given\ number\ of\ steps.\n\ @param\ numSteps\ The\ number\ of\ steps.\n
+comment3.params=
+comment3.target=void\ step()
+comment3.text=\n\ Run\ the\ automaton\ for\ a\ single\ step.\n
+comment4.params=
+comment4.target=void\ reset()
+comment4.text=\n\ Reset\ the\ automaton.\n
+numComments=5

Semester 1/Programming 1/Java/examples/projects/chapter07/automaton-v3/AutomatonController.java

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+/**
+ * Set up and control an elementary cellular automaton.
+ * 
+ * @author David J. Barnes and Michael Kölling
+ * @version  2016.02.29
+ */
+public class AutomatonController
+{
+    // The automaton.
+    private Automaton auto;
+    
+    /**
+     * Create an AutomatonController.
+     * @param numberOfCells The number of cells in the automaton.
+     */
+    public AutomatonController(int numberOfCells)
+    {
+        auto = new Automaton(numberOfCells);
+        auto.print();
+    }
+    
+    /**
+     * Create an AutomatonController with
+     * a default number of cells.
+     */
+    public AutomatonController()
+    {
+        this(50);
+    }
+    
+    /**
+     * Run the automaton for the given number of steps.
+     * @param numSteps The number of steps.
+     */
+    public void run(int numSteps)
+    {
+        for(int step = 1; step <= numSteps; step++) {
+            step();
+        }
+    }
+    
+    /**
+     * Run the automaton for a single step.
+     */
+    public void step()
+    {
+        auto.update();
+        auto.print();
+    }
+    
+    /**
+     * Reset the automaton.
+     */
+    public void reset()
+    {
+        auto.reset();
+        auto.print();
+    }
+}

Semester 1/Programming 1/Java/examples/projects/chapter07/automaton-v3/README.TXT

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+Project: automaton
+Aothors: David J. Barnes and Michael Kölling
+
+This project is part of the material of the book
+
+   Objects First with Java - A Practical Introduction using BlueJ
+   Sixth edition
+   David J. Barnes and Michael Kölling
+   Pearson Education, 2016
+
+It is discussed in chapter 7.

Semester 1/Programming 1/Java/examples/projects/chapter07/automaton-v3/package.bluej

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+#BlueJ package file
+dependency1.from=AutomatonController
+dependency1.to=Automaton
+dependency1.type=UsesDependency
+objectbench.height=76
+objectbench.width=737
+package.editor.height=400
+package.editor.width=629
+package.editor.x=70
+package.editor.y=80
+package.numDependencies=1
+package.numTargets=2
+package.showExtends=true
+package.showUses=true
+project.charset=UTF-8
+readme.editor.height=700
+readme.editor.width=900
+readme.editor.x=53
+readme.editor.y=23
+target1.editor.height=769
+target1.editor.width=980
+target1.editor.x=375
+target1.editor.y=141
+target1.height=50
+target1.name=Automaton
+target1.naviview.expanded=true
+target1.showInterface=false
+target1.type=ClassTarget
+target1.typeParameters=
+target1.width=90
+target1.x=170
+target1.y=160
+target2.editor.height=777
+target2.editor.width=994
+target2.editor.x=286
+target2.editor.y=23
+target2.height=50
+target2.name=AutomatonController
+target2.naviview.expanded=false
+target2.showInterface=false
+target2.type=ClassTarget
+target2.typeParameters=
+target2.width=160
+target2.x=70
+target2.y=70