Intellij idea JDK does not understand or see him?

Intellij idea JDK does not understand or see him? But the code compiles fine.
Here Intellij highlights almost everything that is supposedly speaking do not understand or know.
and he auto tip say the rules, all we see, but as soon as I finish entering, will again become red.
if you look at the options fix the problem all boils down to this
but the JDK is already was originally, it appeared after a reboot
July 9th 19 at 10:48
2 answers
July 9th 19 at 10:50
Apparently the solution to this problem is just one. Reinstalled Intellij IDEA, removing all settings and configurations IDE
July 9th 19 at 10:52
Need to reboot at least three times, and then ask ))
not restarting Intellij or PC does not help, so the advice is useless - loren_Grimes commented on July 9th 19 at 10:55

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