android eclipse does not recognize attributes / autcomplete

i just set up eclipse + android + plugins on a new box here. i'm finding that when i'm editing a layout XML file, eclipse no longer understands the schema. for example, if i type "android:" i'm used to it popping up an auto complete box with the possible completions.

i of course still have the,

xmlns:android="http://schemas.android.com/apk/res/android"

things stil开发者_运维知识库l compile and run correctly.

in my files as before. i'm also noticing that all my XML files have a warning at top of "no grammar contraints detected for this document". i can't be sure this hasn't always been there though. i don't know if it's related.

another post suggested i might need an entry under preferences > xml > xml catalog. i don't see the android URI specified there, but i don't know if this is related either.

EDIT: creating a new android project does not exhibit this issue. there's no warning on the XML files and autocompletion works as expected. however, there's no diff in the .classpath / .settings files. what else could possibly be affecting this project?

EDIT 2: creating a new layout file by doing project > android > new resource file creates a file without this issue. still trying to find how the files gets marked as being an android resource.

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Deleting and re-importing the project solved the problem.