Module 1: Start Coding in Java

Install JDK 25 and Verify `java` and `javac`

Install a current Java 25 JDK, verify the runtime and compiler from the terminal, and avoid outdated JRE-only advice.

Author

Java Learner Editorial Team

Reviewer

Technical review by Java Learner

Last reviewed

2026-04-16

Java version

Java 25 LTS

How this lesson was prepared: AI-assisted draft, edited by hand, and checked against current Java 25 documentation and runnable examples.

Learning goals

Install a JDK instead of looking for a separate JRE download
Check `java -version` and `javac -version` successfully
Understand why the JDK is the right beginner install

Use the JDK, not a separate JRE download: For current Java, beginners should install a JDK. Oracle and OpenJDK distributions no longer focus on a separate end-user JRE download path for modern development.

Why JDK 25 LTS: Java 25 is the current LTS baseline for this course. That gives you a stable version with long-term support while keeping examples current.

What to verify: java -version checks that Java can run. javac -version checks that the compiler is available. If javac is missing, you probably installed the wrong package or your PATH is not set correctly.

Common distributions: Oracle JDK and OpenJDK-based builds such as Eclipse Temurin are both valid learning setups. The important part is that you are on a current JDK, not outdated JRE instructions.

Runnable examples

Check the runtime version

java -version

Expected output

Shows your installed Java runtime version, such as Java 25.

Check the compiler version

javac -version

Expected output

Shows your installed Java compiler version, such as javac 25.

Common mistakes

Installing Java but not verifying `javac`

Always check both `java -version` and `javac -version` after install.

Following old articles that only mention the JRE

For current Java development, install a JDK and use current docs such as Dev.java.

Mini exercise

Run both version commands and write down the exact output you see.

Summary

Install a current JDK, not outdated JRE-only guidance.
`java` runs programs and `javac` compiles source files.
Java 25 LTS is the baseline for this course.

Next step

Once the JDK is installed, run one Java file from the terminal and from an IDE.

Sources used

Install JDK 25 and Verify `java` and `javac`

Check the runtime version

Check the compiler version

Which command confirms that the Java compiler is available?