Ever seen List<Set<Integer>> rowSets = new ArrayList<>() and wondered "Why not new List<Set<Integer>>()?" This fundamental question about interfaces vs concrete classes trips up many Java learners. Let's clear it up through a real conversation.
When you see Set<Integer>[] rowSets = new HashSet[9];, your brain might freeze. What's the array? What are the elements? Why HashSet without <Integer>? And wait - if arrays like int[] are type-safe, why do we even need generics? Let's untangle this confusing syntax and understand why Java works this way.
If fields are private but setters are public, isn't that the same as making the field public? And what's the difference between Long and long anyway? Let's clear up these common Java confusions.
In Part 1, we learned why Spring Data JPA repositories must be interfaces. Now let's understand the fundamental difference between classes and interfaces in Java, and when to use each.
Can you compile Java code without a package declaration? Yes. Should you? Absolutely not. Here's why the package statement is essential, not optional.
Ever wondered what those spring.datasource.* and spring.jpa.* properties actually do when your Spring Boot app starts? Let's trace the complete journey from configuration file to running database, step by step.
Have you ever wondered why you can declare variables with the same name in different parts of your code, but not in others? This article explores Java's variable scoping rules, the concept of shadowing, and the design decisions that make Java a safer language.