User-Defined Methods
Learn Java methods by building a smart home thermostat system that can make comfort-based decisions for multiple rooms and days.
The project
In the previous lesson, you built a smart thermostat that decides whether to turn on the fan, heater, or AC depending on the temperature, season, and peak hours. However, here’s the challenge: right now, your code works only for one room at a time.
What if you want to check the comfort level in the living room, bedroom, and kitchen, each with different temperatures? And what if you want the same room to adjust its temperature based on who is there at that moment?
Copy-pasting the same decision logic again and again is messy, error-prone, and hard to update. Instead, Java gives us a powerful tool: you can define your own methods.
The programming concept
Remember how the built-in methods like System.out.println() feel like handy tools that do something when you call them? Of course, a programmer at Java’s headquarters, or more likely, part of the global developer community, had to define those methods so you could use them. But what if you could create your own? After all, no programming language can possibly include every method anyone might ever need, already packaged and ready to go. For instance, do you really think there would ever be a built-in method called ...