- Java Sealed Class
1. What Are Sealed Classes? Imagine you own a VIP club. You do not let just anyone walk in — you have a guest list. Only people whose names appear on that list are allowed through the door. If someone’s name is not on the list, they cannot enter, no exceptions. A sealed class in […]
- Java Record
1. What is a Record? Java developers have written the same boilerplate code millions of times: a class with private fields, a constructor, getters, equals(), hashCode(), and toString(). For a simple class that carries two fields, you end up writing 40+ lines of code where only two lines — the field…
- Java – Method Reference
1. What is a Method Reference? Imagine you are writing directions for someone. You could say: “Go to the kitchen, open the drawer, pick up the knife, and cut the bread.” Or you could simply say: “Cut the bread” — because the person already knows how to do it. A method reference works the same […]
- Java – Optional
1. What is Optional? Imagine you ask a hotel receptionist for a room key. There are two possible outcomes: either they hand you a key, or they tell you no room is available. In old Java code, the answer to “give me the user with this ID” was either a User object or null — […]
- System Design – Interview Questions
What is the purpose of software system design? Software system design aims to transform user requirements into a well-organized and structured solution by defining system architecture, modules, interfaces, and other components. Explain the difference between monolithic and microservices…