Why is Intelij Idea highlighted in red when importing swing, writes an error, although the program is running?

Question

Java

Intelij Idea when importing swing highlights in red,
that is, in "import javax.swing.*;" the word swing is red and the error "cannot resolve symbol 'swing' " appears in the margins. And, accordingly, further in the code, all " JOptionPane
." are red with the same error in the margins.
as a beginner, they would be very useful to me)

Need advice

Answer 1

It's weird that IDEA doesn't usually do that, it's not Eclipse! If the code works, then it should usually disappear when the platform is restarted.

Answer 2

Check if there are swing libraries in classpath Idea?