How to fix Eclipse validation error “No grammar constraints detected for the document”?

Question

Eclipse 3.5.2 is throwing an XML schema warning message:

No grammar constraints (DTD or XML schema) detected for the document.

The applica

Answer 1

I am not an expert but a learner. I accidentally found an easy and stupid way to solve the problem. What you just need to do is:

Press ctrl + shift + F (it's a shortcut to format the file in Eclipse)

If this does not solve the problem then press the TAB key at the starting of this particular line
?xml version="1.0" encoding="UTF-8"? and not anywhere else (I don't not why, but this works. If anyone here knows why I will be very happy to know)

Then press ctrl + shift + F and save.

The warning will be gone, at least for me, you may try for yourself...