Common Maven Commands

The most commonly used Maven commands are mvn clean, mvn compile, mvn test, mvn package, mvn install, and mvn clean package. Let me explain what each does. Clean removes the target directory where all your compiled code and build artifacts live, so you start fresh. Compile just compiles your Java source code into class files but doesn't run tests or create a JAR. Test compiles your code and runs your unit tests — if any test fails, the build stops right there. Package is probably the command you'll use most often because it does everything: compiles your code, runs your tests, and then creates a JAR or WAR file in the target directory. Install takes it one step further by copying that JAR to your local dot m2 repository, which is useful when you're working on multi-module projects where one module depends on another. And clean package combines clean and package into one command, which is what you use before important builds to make absolutely sure there's no leftover artifacts from previous builds that could cause problems. One really important thing that trips up freshers is that you don't need to run these commands sequentially. If you run mvn package, Maven automatically runs compile and test first because those are earlier phases in the lifecycle. You don't need to type mvn compile then mvn test then mvn package as three separate commands. A bonus command that shows you know your stuff is mvn dependency colon tree. This isn't a lifecycle phase, it's a plugin goal that displays your entire dependency tree including all the transitive dependencies. This is super useful when you're debugging dependency conflicts or trying to figure out where a specific JAR is coming from.