The resource is not on the build path of a Java project error

In Eclipse, you import a project using Maven, but when you perform a f3/f4/ctrl+alt+h operation on a class, you get an error: "The resource is not on thebuild path Of a Java project ".

This often happens when you reopen eclipse.

Cause: The class could not be found in the build path of the project.

Workaround:

1. Locate the file under BuildPath below SRC and remove it and add it again to update all directories.

2. Close the class and turn it back on

The resource is not on the build path of a Java project error