Most likely, you haven't connected the SDK in IntelliJ IDEA. To fix this, in IntelliJ IDEA go to File -> Project Structure -> Platform Settings -> SDKs.
On the Classpath tab, you need to connect all the jar files (they can be found at «Java path»/jre/lib, On Windows, the default Java path is — C:\Program Files\Java).
The task code in IntelliJ IDEA is highlighted in red. What should I do?
Written by Alex Elenevych
Updated over 6 years ago