Ways to resolve Eclipse projects with red exclamation marks

Cause: The red exclamation mark is displayed because the path to the jar package is incorrect

FIX: On project right click on build Path --- Configure build paht ... (or Propertise->java build path), Librariesin the Java build path, the package for the Red Cross is the package with the wrong path.

After processing, return to the Refresh project can, this problem is generally imported into someone else's project or before some jar package moved its storage location.

PS: Project Yellow Shield exclamation point, indicating that there is a reference to the jar package, but actually do not use the jar package (can be understood as defined variables, but used in the future)

Ways to resolve Eclipse projects with red exclamation marks