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Troubleshoot

If the program does not run, follow these simple steps.

Step 1 — Check Your Java Version

  • Open Command Prompt
  • Type the following two commands one after another java -version and javac -version
  • You should see something like this - java version "1.8.0" and javac version 1.8.0

Both versions must match

If not, follow the steps given below

Step 2 — Which Version Should You Use?

This repository is developed and tested using: Java 8

If your version is not Java 8, install it.

Step 3 — Download Java 8 (If you do not want to install a new Java Version, follow Step 5)

Download Java 8 (Recommended: OpenJDK):

 ADOPTIUM

Choose:

  • Windows (or your OS)
  • x64
  • Installer (.msi)

Install it and restart your computer.

Step 4 — Test Again

After restarting, run: java -version and javac -version

Both should show version 1.8

Now compile and run: javac <"FILENAME">.java and java <"FILENAME">

Replace <"FILENAME"> with the program name

Step 5 — Follow This If You Do NOT Want To Install A New Java Version

Check the class file version and the Java Runtime version

Example

Exception in thread "main" java.lang.UnsupportedClassVersionError: <"PROGRAM NAME"> has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 52.0

From here - class file version is class file version 61.0 and Java Runtime version is 52.0

What this mean:

  • The program was compiled using Java 17
  • But your system is running Java 8

Use the reference table given below to check JDK version, Class File Version and their corresponding Compile Command (Force Compatibilty)

JDK Version Class File Version Compile Command
Java 8 52.0 javac --release 8 <"FILENAME">.java
Java 9 53.0 javac --release 9 <"FILENAME">.java
Java 10 54.0 javac --release 10 <"FILENAME">.java
Java 11 55.0 javac --release 11 <"FILENAME">.java
Java 12 56.0 javac --release 12 <"FILENAME">.java
Java 13 57.0 javac --release 13 <"FILENAME">.java
Java 14 58.0 javac --release 14 <"FILENAME">.java
Java 15 59.0 javac --release 15 <"FILENAME">.java
Java 16 60.0 javac --release 16 <"FILENAME">.java
Java 17 61.0 javac --release 17 <"FILENAME">.java
Java 18 62.0 javac --release 18 <"FILENAME">.java
Java 19 63.0 javac --release 19 <"FILENAME">.java
Java 20 64.0 javac --release 20 <"FILENAME">.java
Java 21 65.0 javac --release 21 <"FILENAME">.java
Java 22 66.0 javac --release 22 <"FILENAME">.java

Quick Commmand Line

Recompile using: javac --release <JDK_VERSION> <"FILENAME">.java

Then run: java <"FILENAME">

Replace <"FILENAME"> with the program name

What this does - This forces the program to be compatible with your Java version.

Hope it helps!

If any problems persist, feel free to contact me from the either of the e-mail addresses

© 2026 Hardik Basu