Download the latest JDK from Oracle or Adoptium . Without this, DrJava will open but won't be able to compile your .java files.
Click the "Compile" button to turn your source code into bytecode. download drjava
While heavy-duty IDEs like Eclipse or IntelliJ IDEA are industry standards for professional development, they can be overwhelming for those just starting. DrJava focuses on: Download the latest JDK from Oracle or Adoptium