flyweight added

Author: maciej-nowak

flyweight/README.md

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+# flyweight
+This is repository of http://androidcode.pl blog. It shows uses of Flyweight pattern in Android. It is a part of Design Patterns - Flyweight post in the blog.

flyweight/example/DetailsFactory.java

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+public class DetailsFactory {
+
+    private static Map<Type, Details> types  = new HashMap<>();
+
+    public static Details getPlantDetails(Type type) {
+        Details item = types.get(type);
+        if(item == null) {
+            item = new Details(type);
+            types.put(type, item);
+        }
+        return item;
+    }
+}

flyweight/example/Main.java

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+public class Main {
+    
+    public static void main() {
+        //user start new game so the board is creating
+        //a lot of trees are in the board, so create all types of the tree and reuse them
+
+        for(int i=0; i<1000; i++) {
+            //random type of the plant and get it from cache factory
+            Type type = randomType();
+            Details details = DetailsFactory.getTreeType(type);
+
+            //random position of the tree on the board
+            Position position = randomPosition();
+
+            //create plant based on the type and position
+            //Factory method can be used, but for simplify just if-else
+            Plant plant;
+            if(type == Type.OAK || type == Type.PINE || Type.CHESTNUT) {
+                plant = new Tree(point, data);
+            }
+            else if(type == Type.ROSE || Type.TULIP || Type.HEATHER) {
+                plant = new Flower(point, data);
+            }
+
+            //put the plant on the map
+            plant.draw();
+        }
+    }
+
+    public static Position randomPosition(int min, int max) {
+        int x = randomValue(100, 100);
+        int y = randomValue(100, 100);
+        int z = randomValue(20, 20);
+        return new Position(x, y, z);
+    }
+
+    public static int randomValue(int min, int max) {
+        return min + (int) (Math.random() * ((max - min) + 1));
+    }
+}

flyweight/example/dummy/Position.java

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+public class Position {
+	
+	private int x, y, z;
+
+	public Position() {
+		x = 0;
+		y = 0;
+		z = 0;
+	}
+
+	public Position(int x, int y, int z) {
+		this.x = x;
+		this.y = y;
+		this.z = z;
+	}
+
+	//getter, setter and other methods
+}

flyweight/example/dummy/Texture.java

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+public class Texture {
+
+	//graphics texture for map items
+	//heavy object
+
+	//some fields, constructors and methods
+}

flyweight/example/dummy/Type.java

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+public enum Type {
+
+	OAK(0),
+	PINE(1),
+	CHESTNUT(2),
+	ROSE(3),
+	TULIP(4),
+	HEATHER(5);
+	//etc
+
+	private int type;
+
+	public Type(int type) {
+		this.type = type;
+	}
+}

flyweight/example/flyweights/Details.java

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+public class Details {
+
+    private Type type;
+    private Texture texture;
+    private String data;
+
+    public Details(Type type) {
+        this.type = type;
+        loadTexture();
+        loadData();
+        this.texture = texture;
+        this.data = data;
+    }
+
+    private void loadTexture() {
+        //load texture based on the type
+    }
+
+    private void loadData() {
+        //load additional data based on the type
+    }
+
+    //some methods
+}

flyweight/example/flyweights/Flower.java

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+public class Flower extends Plant {
+
+    @Override
+    public void draw() {
+        //draw concrete type of the flower in the point in specific way
+    }
+}

flyweight/example/flyweights/Plant.java

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+public abstract class Plant {
+    
+    private Point point;
+    private Data data; //consume a lot of memory
+
+    public Plant(Point point, Data data) {
+        this.point = point;
+        this.data = data;
+    }
+
+    public abstract void draw();
+}

flyweight/example/flyweights/Tree.java

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+public class Tree extends Plant {
+
+    @Override
+    public void draw() {
+        //draw concrete type of the tree in the point in specific way
+    }
+}

flyweight/pattern/FlyweightFactory.java

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+public class FlyweightFactor {
+
+    //if there are more types of flyweight classes than use Factory method
+
+    public static Map<String, Flyweight> flyweightTypes = new HashMap<>();
+
+    public static Flyweight getFlyweight(String type, int value) {
+        Flyweight flyweight = flyweightTypes.get(type);
+        if(result == null) {
+            result = new ConcreteFlyweight(name, value);
+            flyweightTypes.put(name, result);
+        }
+        else {
+            result.setValue(value);
+        }
+        return result;
+    }
+}

flyweight/pattern/Main.java

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+public class Main {
+	
+	public static void main() {
+		//3 types of items can be created so reuse those items instead of creation new one
+		String types[] = { "Type1", "Type2", "Type3" };
+
+		//generate a lot of items for example in loop with random values
+		for(int i=0; i<100; i++) {
+		    //get random type and value
+		    String type = randomType(types);
+		    value = randomValue(0, 100);
+		    //get flyweight item from factory and do operation
+		    Flyweight flyweight = FlyweightFactory.getFlyweight(type, value);
+		    flyweight.operation();
+		}
+		//factory created only 3 items: Type1, Type2, Type3 and rest of 97 have been reused
+	}
+
+	public static int randomValue(int min, int max) {
+    	return min + (int) (Math.random() * ((max - min) + 1));
+	}
+
+	public static int randomType(String[] type) {
+	    return types[(int)(Math.random() * types.length)];
+	}
+}

flyweight/pattern/flyweights/ConcreteFlyweight.java

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+public class ConcreteFlyweight implements Flyweight {
+
+    private String type;
+    private int value;
+
+    public ConcreteFlyweight(String type, int value) {
+        //creation of object is consuming resources
+        this.type = type;
+        this.value = value;
+    }
+
+    @Override
+    public void operation() {
+        //do specific operation for ConcreteFlyweight
+    }
+
+    public void setValue(int value) {
+        this.value = value;
+    }
+
+    //other setters and getters
+}

flyweight/pattern/flyweights/Flyweight.java

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+interface Flyweight {
+
+    void operation();
+}