Hello, dear friends. In this video, we will examine the Flyweight Design Pattern. Let's begin. Sometimes the objects in an application might have great similarities and be of a similar kind. In case they are also heavy objects to create, they should be controlled by the application developer, otherwise they might consume much of the memory and eventually slow down the whole application. The flyweight pattern is designed to control such kind of object creation, and provides you with a basic cacheing mechanism. It allows you to create one object per type, and if you ask for an object with the same property, it will return you the same object instead of creating a new one. According to GoF, flyweight design pattern enables the use of sharing of objects to support large numbers of fine grained objects efficiently. As you can see in this UML diagram, the structure of flyweight is very simple.

Flyweight design pattern is a structural design pattern. Flyweight design pattern is used when we need to create a lot of objects of a class, since every object consumes memory space that can be crucial for low memory devices such as mobile devices or embedded systems. Flyweight design pattern can be applied to reduce the load on memory by sharing objects. Before we apply the flyweight design pattern, we need to consider some important factors. An application must use a considerable number of objects because the number of objects, the storage costs are high. The application does not depend on object identity. There are two important advantages of flyweight. The first is that flyweight reduces the number of objects to deal with. The second is that flyweight reduces the amount of memory and storage devices required if the objects are persisted. I think that's enough. Let's create a project using the flyweight pattern. Let's take, for example, a car assembly factory.

First, we need an interface. Let's name it Car. We need a method. Let's name it assemble( ) ;. Let's define our first car, maybe Mercedes implements Car {. We have to override assemble method. Let's another one as Jaguar. Override method. Let's add another one. Maybe, Citroen. Done. First, import HashMap. Let's create our CarFactory class. To find a HashMap for cars, name a string. Now, we need a get method for cars. This will take a parameter as carType. Now, we can check carType with a condition, but first make empty control. Mercedes. Save the memory. If you want, you can copy this code and change for Jaguar. Last one is Citroen. Return car. Now, we have finished to create our structure. Let's use. First, we need a static CarFactory. Now, let's add loop for Mercedes. I want to give location of cars. Let's add another loop for Jaguar. And of course, I want to add for Citroen. Now, if we run this project, we can see nine cars with positions. Actually, there are no advantages of using the flyweight pattern in this project. But for large projects, these loops may work for 100,000.

And in that case, this pattern will give us a significant advantage. As you can see, we can see our cars. Now, I believe that's enough for flyweight pattern. In the next video, we'll move on to another structural pattern called the Proxy Design Pattern. See you in the next video.