Java: Prepare For Design Pattern Interviews

With Real world design scenarios

In this article we will have some scenario-based design pattern interview questions in Java that focus on best practices.

Question 1

Scenario

You’re developing a Java application that processes various types of files (e.g., XML, JSON, CSV). The processing steps are similar but have slight variations depending on the file type. You notice that adding new file types leads to code duplication and makes the codebase harder to maintain.

Question

How would you redesign your application to handle multiple file types efficiently while promoting code reuse and maintainability? Which design pattern(s) would you apply, and why?

Answer:

Use the Template Method Pattern to define the skeleton of the file processing algorithm in a base class, leaving the implementation of the variable steps to subclasses representing each file type. This promotes code reuse by encapsulating common behavior and allows easy addition of new file types without modifying existing code. Here’s how I would implement it:

• Abstract Class (FileProcessor): Defines the template method (processFile) and implements the common steps.