Guys I wanna do android dev. Don't wanna make it my mainstream but need it for some projects. So which is an easy way to develop mobile apps? I dont wanna do android studio. Maybe a JS framework.

If not Java and JS, cordova ist probably the way to go. You can develope your app (nearly) like a normal Website and to use phone specific stuff there are tons of easy to use plugins.
The documentation should give you a good start.

I want the dev process to be simple and fast. What is ur opinion about react?