Unable to build: the file dx.jar was not loaded from the SDK folder in my eclipse

This SO answer provides more details if removing build automatically / rebuilding doesn't work.

It worked for me.

I removed build automatically and then build whole workspace some how it worked for me :)

from Android ADT error, dx.jar was not loaded from the SDK folder:

"add this in the project.properties of your project: sdk.buildtools=25.0.2"