If you need a clean way to manage config in a Java app—things like API keys, database URLs, feature flags, or buffer sizes—this video is my full, step-by-step guide to reading a .properties file using Java’s built-in Properties class. I start with a simple config.properties file that has key/value pairs (app name, version, dark mode boolean, and a buffer size), and the goal is to load those values into a Java program without hardcoding them. In the code, I create an instance of java.util.Properties, then I read the file safely with a try-with-resources block. That’s a best practice I always recommend because it auto-closes the FileInputStream and helps you avoid resource leaks. The key step is calling properties.load(inputStream), which pulls in the full file at once. After that, I use getProperty("key") to retrieve values, and I also call out an important detail: getProperty always returns a String. So if you need booleans or integers, you have to parse them yourself (like Boolean.parseBoolean and Integer.parseInt). By the end, everything prints correctly, and you’re ready to use those config values anywhere in your application.