Eclipse: The declared package does not match the expected package

Question

I have a problem importing an external project. I go File -> Import... -> Existing Projects into Workspace, choose the folder where the project is located and everything is

Answer 1

Just go into the build path and change the source path to be src/prefix1 instead of src.

It may be easiest to right-click on the src directory and select "Build Path / Remove from build path", then find the src/prefix1 directory, right-click it and select "Build Path / Use as source folder".