Learn Java for Web Development

CHAPTER 5: Building Java Web Applications with Spring Web MVC 213

Listing 5-13. Vehicle Service

1. public class VehicleService {


2. 
   


3. private Vehicle vehicle = new Bike();


4. 
   


5. public void driver() {


6. System.out.println(vehicle.drive());


7. 
   


8. }


9. 
   


10. }

   Line 3: In Listing 5-13, class Bike is the dependency of class VehicleService

and is instantiated on line 3. This is a case of tight coupling because the class

VehicleService is implementation-aware of the Vehicle object, which is Bike in

this case.

Listing 5-14 illustrates the stand-alone VehicleApp.

Listing 5-14. Stand-Alone VehicleApp

1. public class VehicleApp {


2. public static void main(String[] args) {


3. VehicleService service = new VehicleService();


4. service.driver();


5. }


6. }

As illustrated in Listing 5-14, VehicleService is implementation-aware of the Vehicle object and
hence tightly coupled to it. Now let’s decouple this application through the Spring Framework’s DI.
The first step is to create a Java project using the Eclipse IDE. Select File ➤ New ➤ Project and
then select Java Project Wizard from the wizard list. Name your project looselyCoupledApplication
using the wizard, as illustrated in Figure 5-2.