These guides build real Android apps in Android Studio, with complete working code. No fragments that assume you already know the rest.
Which project should you start with?
A flashlight app. It sounds trivial and it is not — it teaches layouts, runtime permissions, hardware access and lifecycle, which is nearly everything a small app needs. You can finish it in an evening and it runs on a real phone.
After that, pick by what you actually want to ship:
- Turning an existing website into an app — the fastest route, but read the Play Store section first
- A chat app — a full weekend project with a real server behind it
- Adding AdMob — once you have something worth putting ads in
Test on a real phone, not the emulator
The emulator has no flash, handles calls badly and behaves differently on permissions. A correct app will look broken there, and you will spend an hour debugging code that was fine.
Enable USB debugging on a real device and use that from the start.
Two Play Store rules that catch people out
A WebView wrapper on its own gets rejected. Google Play policy requires an app to provide value beyond simply displaying a website. Add push notifications, offline content or native file uploads before submitting, or expect a rejection.
Never click your own AdMob ads. Not even once, not even to check they work. Google detects invalid traffic automatically, an AdMob ban is usually permanent, and appeals rarely succeed. Use the official test ad IDs during development.
What apps actually earn
Honest figures, because most guides are not: banner ads pay roughly $0.20 to $1.50 per thousand views, interstitials $2 to $12, rewarded video $8 to $25.
Audience location matters more than anything else — the same app can earn ten times more depending purely on where its users are. An app with 1,000 daily users in a low-rate region earns a few dollars a day, not a few hundred.
Free open-source code is a fair starting point
Several excellent Android apps are open source under GPL v3, which permits commercial use. The condition is that if you distribute your version, you must also make your modified source available. Read the licence before building a paid product on one.