The JDK is a software package you install on your machine. It contains the JRE, the JVM, and all the development tools.
Different JDK distributions comply with JDK specifications:
| Implementation | Provider | Cost |
|---|---|---|
| OpenJDK | Oracle/Community | Free |
| Temurin | Adoptium | Free |
| Corretto | Amazon | Free |
| Oracle JDK | Oracle | Paid |
| Zulu | Azul | Free/Paid |
| GraalVM | Oracle/Community | Free/Paid |
When you install the JDK, you get several command-line tools.
| Tool | Command | What it does | JS/Node Equivalent |
|---|---|---|---|
| Compiler | javac | Converts .java (source) to .class (bytecode). | tsc (TypeScript Compiler) |
| Launcher | java | Starts the JVM and runs your compiled class. | node index.js |
| Archiver | jar | Packages your code into a single .jar file. | npm pack or Webpack/Rollup |
| Documentation | javadoc | Generates HTML documentation from your comments. | JSDoc |
javac -version
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If get an error similar to “javac cannot be found”, try to restart your terminal application
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For more information about installing OpenJDK you can check the official website : https://openjdk.org/install/
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Many Java tools (like Maven, Gradle, or IntelliJ) look for an Environment Variable called JAVA_HOME. This is the path to the root folder of your JDK.
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In the Java world, the most popular tool for managing versions is SDKMAN!. It works on macOS, Linux, and Windows (via WSL). https://sdkman.io/
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