1、 Origin of the problem

In the afternoon, the computer was well used. Suddenly, it crashed. What can I do?I can only restart it. When you open idea again, all the previously opened projects

The information was gone. I reopened the project, and then there was a problem. All classes reported red, which surprised me. How could this happen?

2、 Problem analysis

According to my analysis, the problem may be that the idea is not shut down normally because the computer is not shut down normally, so there is a problem when you use it again. This is my simple judgment,

From this point of view to find a solution.

3、 Solution

Try 1: re import the project, re set maven, and re set JDK. It has no effect.

Try 2: select the pom.xml file and right-click to re import the jar package. There is no effect.

Try 3: select Maven for clean operation, and then select compile to report the error in the title, but it still has no effect.

Try 4: restart the computer, restart idea, and open the project again, but it still has no effect;

Try 5: select idea file — & gt; Invalidate Cashed/Restart。 Problem solving.