Android Studio 3.0 xml-layout file's preview not showing
Cleaning and rebuilding my project solved the issue.
try different theme (may be from Appcompat) and API level from top
OR
- If you have made some changes in the layout just undo it.
- delete .idea and .gradle folder from root of the project
- close android studio , restart it
- click on gradle icon from right sidebar and click sync icon to refresh project. now rebuild the project and it should work.
After a lot searching and I tried all solution which people give here, but any of them didn't solve my problem, I guess this problem is from studio's developers, and they may fix it in next patch. so I simply re-installed my android studio and it's solved.