Flyweight design pattern - AFTER CODE with with reusable cached object to reduce memory foot print

Author: premaseem

pattern/src/com/premaseem/Client.java

@@ -9,6 +9,28 @@ public class Client {
     public static void main (String[] args) {
         System.out.println("Flyweight design pattern using ** STAR WARS **  example");
 
+        // Create Landscape object which is responsible to display stars
+        Landscape landscape = new Landscape();
+
+        // Factory will provide star based on param
+        // Note: Factory will cache objects for reuse
+        // and will create new object only when it does not exist in cache.
+        Star star = StarFactory.getStar("dull");
+
+        landscape.displayStar(star,65,87);
+
+        // No new object needs to be created, Factory provides reusable object
+        // from cache which landscape displays
+        landscape.displayStar(StarFactory.getStar("bright"),34,43);
+        landscape.displayStar(StarFactory.getStar("bright"),36,47);
+        landscape.displayStar(StarFactory.getStar("dull"),34,43);
+        landscape.displayStar(StarFactory.getStar("dim"),34,43);
+        landscape.displayStar(StarFactory.getStar("dim"),34,43);
+
+
+
+
+        /* OLD Scrapped code
         // Created 1000 stars with brightness level bright
         Star brightStar1 = new Star("bright");
         Star brightStar2 = new Star("bright");
@@ -51,5 +73,6 @@ public static void main (String[] args) {
         landscape.displayStar(dullStar2,34,45);
         landscape.displayStar(dullStar3,23,55);
         landscape.displayStar(dullStar1000,34,45);
+    */
     }
 }

pattern/src/com/premaseem/Star.java

@@ -5,12 +5,59 @@
 @title: Design Patterns with Java 9
 @link: https://premaseem.wordpress.com/category/computers/design-patterns/
 */
-public class Star {
+public interface Star {
+    void displayBrightness ();
+}
+
+class BrightStar implements Star {
+
+    private String brightness;
+
+    public BrightStar () {
+        this.brightness = "bright";
+    }
+
+    @Override
+    public void displayBrightness () {
+        System.out.println("Star with brightness :" + brightness);
+    }
 
-     String brightness;
+    @Override
+    public String toString () {
+        return "Star with brightness :" + brightness;
+    }
+}
+
+class DimStar implements Star {
 
-    public Star (String brightness) {
-        this.brightness = brightness;
+    private String brightness;
+
+    public DimStar () {
+        this.brightness = "dim";
+    }
+
+    @Override
+    public void displayBrightness () {
+        System.out.println("Star with brightness :" + brightness);
+    }
+
+    @Override
+    public String toString () {
+        return "Star with brightness :" + brightness;
+    }
+}
+
+class DullStar implements Star {
+
+    private String brightness;
+
+    public DullStar () {
+        this.brightness = "dull";
+    }
+
+    @Override
+    public void displayBrightness () {
+        System.out.println("Star with brightness :" + brightness);
     }
 
     @Override

pattern/src/com/premaseem/StarFactory.java

@@ -0,0 +1,41 @@
+package com.premaseem;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/*
+@author: Aseem Jain
+@title: Design Patterns with Java 9
+@link: https://premaseem.wordpress.com/category/computers/design-patterns/
+*/
+public class StarFactory {
+        static Map<String,Star> starCache = new HashMap<>();
+
+    public static Star getStar (String brightnessLevel) {
+
+        // First try to retrieve object from cache
+        Star star = starCache.get(brightnessLevel);
+
+        // if star does not exist in cache then factory will create one and store it in cache
+        if (star == null) {
+            if (brightnessLevel.equalsIgnoreCase("bright")) {
+                star = new BrightStar();
+                starCache.put("bright",star);
+            }
+            if (brightnessLevel.equalsIgnoreCase("dim")) {
+                star = new DimStar();
+                starCache.put("dim",star);
+            }
+            if (brightnessLevel.equalsIgnoreCase("dull")) {
+                star = new DullStar();
+                starCache.put("dull",star);
+            }
+
+        }
+        // return star object for reuse
+        return star;
+    }
+
+
+}
+