initial simulation code

ChrisMayfield · ChrisMayfield · commit aeda14947906 · 2019-07-18T16:34:32.000-04:00
diff --git a/ch15/Actor.java b/ch15/Actor.java
@@ -0,0 +1,20 @@
+import java.awt.Graphics;
+
+/**
+ * Simulation element.
+ */
+public interface Actor {
+
+    /**
+     * Updates the state of the simulation element.
+     */
+    void act();
+
+    /**
+     * Paints the simulation element in the context.
+     * 
+     * @param g graphics context
+     */
+    void draw(Graphics g);
+
+}
diff --git a/ch15/Drawing.java b/ch15/Drawing.java
@@ -0,0 +1,54 @@
+import java.awt.Canvas;
+import java.awt.Color;
+import java.awt.Graphics;
+import java.util.ArrayList;
+
+/**
+ * Draws a collection of actors.
+ */
+public class Drawing extends Canvas {
+
+    private ArrayList<Actor> actors;
+
+    /**
+     * Constructs a drawing of given size.
+     * 
+     * @param width the width in pixels
+     * @param height the height in pixels
+     */
+    public Drawing(int width, int height) {
+        setSize(width, height);
+        setBackground(Color.white);
+        actors = new ArrayList<Actor>();
+    }
+
+    /**
+     * Adds a new actor to the drawing.
+     * 
+     * @param actor the actor to add
+     */
+    public void add(Actor actor) {
+        actors.add(actor);
+    }
+
+    /**
+     * Calls the act method of each actor.
+     */
+    public void action() {
+        for (Actor actor : actors) {
+            actor.act();
+        }
+    }
+
+    /**
+     * Draws all the actors on the canvas.
+     * 
+     * @param g graphics context
+     */
+    public void paint(Graphics g) {
+        for (Actor actor : actors) {
+            actor.draw(g);
+        }
+    }
+
+}
diff --git a/ch15/Main.java b/ch15/Main.java
@@ -0,0 +1,41 @@
+import javax.swing.JFrame;
+
+/**
+ * Example simulation of moving objects.
+ */
+public class Main {
+
+    /**
+     * Sets up the drawing, creates the actors, and runs the simulation.
+     * 
+     * @param args command-line arguments
+     */
+    public static void main(String[] args) {
+
+        // set up the drawing and add actors
+        Drawing drawing = new Drawing(800, 600);
+
+        // set up the window frame
+        JFrame frame = new JFrame("Drawing");
+        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        frame.add(drawing);
+        frame.pack();
+        frame.setVisible(true);
+
+        // main simulation loop
+        while (true) {
+
+            // update the drawing
+            drawing.action();
+            drawing.repaint();
+
+            // delay the simulation
+            try {
+                Thread.sleep(10);
+            } catch (InterruptedException e) {
+                // do nothing
+            }
+        }
+    }
+
+}
