Java Interview Questions

Catches candidates who memorized Java syntax but don't understand how reference types work in memory, which leads to subtle bugs in production.

Separates developers who just write code from those who understand what the JVM is doing underneath. GC awareness is the difference between 'it works' and 'it works under load.'

Reveals whether the candidate picks data structures based on actual performance characteristics or just defaults to ArrayList for everything.

Shows how the candidate thinks about error handling as a design decision, not just a compiler complaint to silence.

Tests hands-on Spring Boot familiarity. A candidate who can't set up a basic controller without Googling every annotation will struggle with real feature work.

Tells you how the candidate actually works day-to-day. Someone who can only println-debug will be slow on complex codebases.

Encapsulation sense is one of the clearest signals of someone who writes maintainable code vs. someone who just makes things compile.