Day 17/90: Inheritance
90 Day Java Challenge: Zero to Production
Today I wanted inheritance to feel like a real engineering decision, not a syntax demo. The useful shift was using inheritance to make object boundaries and state transitions easier to trust.
The checks that mattered were constructors that lock in valid state, type boundaries that explain ownership, and abstractions that remove duplication without hiding behavior.
The failure mode I was actively trying to avoid was using inheritance or interfaces before deciding which type actually owns the behavior. I wanted inheritance to feel like something I could explain at a whiteboard or in a code review, not just something I recognized from docs.
That is the bar I want from this track: code that stays readable when requirements move, not just code that compiles today. I also want to keep tracing one concrete path through the code because that exposes weak assumptions faster than a larger demo.
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