What Version of Java Do I Have?

Run java -version in any terminal — it works on Windows, Mac and Linux. The first number in the output is your major Java version.

One-command answer

java -version

Reading the output

Why does it say "1.8" instead of "8"?

Java 8 and older used a 1.x versioning scheme: Java 1.0, 1.1, …, 1.4, 1.5, 1.6, 1.7, 1.8. Starting with Java 9 (2017), Oracle switched to simple major version numbers: 9, 10, 11, 17, 21. So 1.8.x is Java 8, and any version number above 8 is what it says.

What if java -version fails?

• "command not found" / "not recognized" — Java is not installed or not on PATH. Install Java.
• Wrong version prints — multiple JDKs are installed. Run where java (Windows) or which java (Mac/Linux) to see which one is active. Change JAVA_HOME and PATH to switch.

Check the Java version from inside a Java program

// Works in any Java version:
System.out.println(System.getProperty("java.version"));
// Java 9+:
System.out.println(Runtime.version().feature()); // prints just the major version (21)

Check the version your build tool expects

Your code's minimum Java version is declared in the build file:

<!-- Maven pom.xml -->
<properties>
  <maven.compiler.source>21</maven.compiler.source>
  <maven.compiler.target>21</maven.compiler.target>
</properties>

// Gradle build.gradle
java {
    toolchain { languageVersion = JavaLanguageVersion.of(21) }
}