For #5 - Implemented Caching Adapter

src/main/java/design/patterns/adapter/caching/AdapterCachingDemo.java

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+package design.patterns.adapter.caching;
+
+import design.patterns.adapter.caching.adapters.LineToPointAdapter;
+import design.patterns.adapter.caching.model.Line;
+import design.patterns.adapter.caching.model.Point;
+import design.patterns.adapter.caching.model.VectorObject;
+import design.patterns.adapter.caching.model.VectorRectangle;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+// used when the interface you have is not the interface you need
+
+// In this example, caching is used to prevent generating the same
+// lines multiple times with successive calls to the draw method.
+
+public class AdapterCachingDemo {
+
+    public AdapterCachingDemo() {
+    }
+
+    private final static List<VectorObject> vectorObjects =
+            new ArrayList<>(Arrays.asList(
+                    new VectorRectangle(1,1,10,10),
+                    new VectorRectangle(3, 3, 6, 6)
+            ));
+
+    public static void drawPoint(Point point) {
+        System.out.println(".");
+    }
+
+    private static void draw() {
+        for(VectorObject object : vectorObjects) {
+            for(Line line : object) {
+                LineToPointAdapter adapter = new LineToPointAdapter(line);
+                adapter.forEach(AdapterCachingDemo::drawPoint);
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+
+        draw();
+        draw();
+
+    }
+}

src/main/java/design/patterns/adapter/caching/adapters/LineToPointAdapter.java

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+package design.patterns.adapter.caching.adapters;
+
+import design.patterns.adapter.caching.model.Line;
+import design.patterns.adapter.caching.model.Point;
+
+import java.util.*;
+import java.util.function.Consumer;
+
+public class LineToPointAdapter implements Iterable<Point> {
+
+    private static int count = 0;
+    private static Map<Integer, List<Point>> cache = new HashMap<>();
+    private int hash;
+
+
+    public LineToPointAdapter(Line line) {
+
+        hash = line.hashCode();
+
+        if(cache.containsKey(hash)) {
+            return;
+        }
+
+        int x1 = line.getStart().getX();
+        int y1 = line.getStart().getY();
+        int x2 = line.getEnd().getX();
+        int y2 = line.getEnd().getY();
+
+        System.out.println(
+                String.format("%d: Generating points for line [%d,%d]-[%d,%d] (caching)",
+                        ++count, x1, y1, x2, y2));
+
+        ArrayList<Point> points = new ArrayList<>();
+
+        int left = Math.min(x1, x2);
+        int right = Math.max(x1, x2);
+        int top = Math.min(y1, y2);
+        int bottom = Math.max(y1, y2);
+        int dx = right - left;
+        int dy = y2 - y1;
+
+        if(dx == 0) {
+            for(int y = top; y <= bottom; ++y) {
+                points.add(new Point(left, y));
+            }
+        }
+        else if(dy == 0) {
+            for(int x = left; x <= right; ++x) {
+                points.add(new Point(x, top));
+            }
+        }
+        cache.put(hash, points);
+    }
+
+    @Override
+    public void forEach(Consumer<? super Point> action) {
+        cache.get(hash).forEach(action);
+    }
+
+    @Override
+    public Spliterator<Point> spliterator() {
+        return cache.get(hash).spliterator();
+    }
+
+    @Override
+    public Iterator<Point> iterator() {
+        return cache.get(hash).iterator();
+    }
+}

src/main/java/design/patterns/adapter/caching/model/Line.java

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+package design.patterns.adapter.caching.model;
+
+import java.util.Objects;
+
+public class Line {
+
+    Point start, end;
+
+    public Line(Point start, Point end) {
+        this.start = start;
+        this.end = end;
+    }
+
+    public Point getStart() {
+        return start;
+    }
+
+    public void setStart(Point start) {
+        this.start = start;
+    }
+
+    public Point getEnd() {
+        return end;
+    }
+
+    public void setEnd(Point end) {
+        this.end = end;
+    }
+
+    @Override
+    public String toString() {
+        return "Line{" +
+                "start=" + start +
+                ", end=" + end +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Line line = (Line) o;
+        return Objects.equals(start, line.start) &&
+                Objects.equals(end, line.end);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(start, end);
+    }
+}

src/main/java/design/patterns/adapter/caching/model/Point.java

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+package design.patterns.adapter.caching.model;
+
+import java.util.Objects;
+
+public class Point {
+
+    private int x, y;
+
+    public Point(int x, int y) {
+        this.x = x;
+        this.y = y;
+    }
+
+    public int getX() {
+        return x;
+    }
+
+    public void setX(int x) {
+        this.x = x;
+    }
+
+    public int getY() {
+        return y;
+    }
+
+    public void setY(int y) {
+        this.y = y;
+    }
+
+    @Override
+    public String toString() {
+        return "Point{" +
+                "x=" + x +
+                ", y=" + y +
+                '}';
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Point point = (Point) o;
+        return x == point.x &&
+                y == point.y;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(x, y);
+    }
+}

src/main/java/design/patterns/adapter/caching/model/VectorObject.java

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+package design.patterns.adapter.caching.model;
+
+import java.util.ArrayList;
+
+public class VectorObject extends ArrayList<Line> {
+}

src/main/java/design/patterns/adapter/caching/model/VectorRectangle.java

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+package design.patterns.adapter.caching.model;
+
+public class VectorRectangle extends VectorObject {
+
+    public VectorRectangle(int x, int y, int width, int height) {
+
+        add(new Line(new Point(x, y), new Point(x+width, y)));
+        add(new Line(new Point(x+width, y), new Point(x+width, y+height)));
+        add(new Line(new Point(x, y), new Point(x, y+height)));
+        add(new Line(new Point(x, y+height), new Point(x+width, y+height)));
+    }
+}