Addressing Intricate Challenges in Legacy Code through the Application of SOLID Principles in Java and Kotlin.

Legacy codebases often exhibit intricate logic, convoluted nested if-else statements, and tightly coupled classes. These characteristics render the code challenging to maintain, extend, and test effectively. In this blog, we will examine the process of refactoring such code by applying SOLID principles in Java, followed by a transition to Kotlin to utilize its advanced features for a more refined solution. Consider a legacy Java class responsible for managing various notification types (email, SMS, push) according to user preferences and system conditions. The implementation is a complex web of if-else statements, complicating the addition of new notification types or the modification of existing logic.

public class NotificationService {
public void sendNotification(String user, String message, String type) {
if (type.equals("email")) {
// Complex email sending logic
System.out.println("Sending email to " + user + ": " + message);
} else if (type.equals("sms")) {
// Complex SMS sending logic
System.out.println("Sending SMS to " + user + ": " + message);
} else if (type.equals("push")) {
// Complex push notification logic
System.out.println("Sending push notification to " + user + ": " + message);
} else {
throw…