vhandit

So far, the Template Method has been my most used design pattern. That is the reason why this post is quite long. J Definition from Wiki The Template Method defines the program skeleton of an algorithm in a method, deferring some steps to subclasses. It lets one redefine certain steps of an algorithm without changing the algorithm's structure. A Real World Use Case Imagine that you have many different kinds of documents. You want to generate a pdf file from a corresponding word template. Each type has its own small modifications but the main process for document generating is the same. We apply the Template Method for this case. We define a final method including some steps (such as preparing for content, generating file) at a superclass. There are three possibilities for these steps at subclasses: Must be overridden: abstract methods. Not mandatory to be overridden: default protected methods. Can not be overridden: default private methods. Dissecting the Patt...

For example, I have a program with an Animal abstract class and two sub-classes Dog and Bird. I want to add new behavior for the class Animal, this is "fly".  Now, I face two approaches to solve this issue: 1. Adding an abstract method "fly" into the class Animal. Then, I force the sub-classes should be implemented this method, something like: public abstract class Animal{ //bla bla public abstract void fly(); } public class Bird extends Animal{ //bla bla public void fly(){ System.out.println("Fly high"); } } public class Dog extends Animal{ //bla bla public void fly(){ System.out.println("Cant fly"); } } 2. Creating an interface with method "fly" inside. The same issue to an abstract class, I force the classes these implement this interface should have a method "fly" inside: public interface Flyable{ public void fly(); } public class Bird implements Flyable{ //bla bla public void fly(){ System.out.pr...