MVP Architecture is one of the most popular architecture to develop a maintanable and managable codebase. We are developing a sample Weater Forecast Android App with MVP Architecture using Kotlin language and Retrofit network calling library.

For simplicity, in this project I don't use any dependency injection framework. With the same project concept there is another repository where I implemented Dagger 2 dependency injection library. You can check that repository after this one.

There is another repository for the same project in MVVM Architecture. Check MVVM repository from here.

We will develop a weather forecast Android Application with MVP architecture. The UI will be as like as above screenshot. There is a Spinner with some City name. After selection a city user need to hit the View Weather button. Then App will send request to Open Weather web API and show the weather information in the UI.

We will use Open Weather Map API for collecting weather information. To get the real weather information of a city, you need to sign up and get your own APP ID. Otherwise you can test the API with their sample BASE URL and sample APP ID without creating account.

Clone the project and open it using Android Studio. Then open your local.properties file under Gradle Scripts. You need to specify the base_url and app_id in your local.properties file. Store your API secret in plain string file or Kotlin file is very risky. For security purpose it's better store in local.properties file than plain string/Kotlin file.

Add below lines at the end of your local.properties file. Then run the project. You'll get dummy or static API response from Open Weather API.

#this is sample Base URL
base_url=https://samples.openweathermap.org/data/2.5/

#this is sample App ID of Open Weather API
app_id=b6907d289e10d714a6e88b30761fae22

After Sign up at the website collect your own APP ID from their API Keys page. Then add below lines with your APP ID at the end of local.properties file.

#this is real Base URL
base_url=http://api.openweathermap.org/data/2.5/

#this is real App ID of Open Weather API
app_id=YOUR_OWN_APP_ID

The BASE URL and APP ID will be fetched from build.gradle file and will be stored it in BuildConfig. And Retrofit API call will use the BASE URL and APP ID from BuildConfig.

Note: The free version of Open Weather API allows maximum 60 API calls per minute.

Sync the Gradle and run the project. Install APK on your emulator or real device. Turn on the internet of your testing device. For better understanding, please read the comments of every methods. Hope, these comments will help you to feel the MVP Architecture.

There are some other ways of implementation of MVP. There are some arguments about the responsibilities of presenter and model. After understanding the basic part of MVP Architecture you can test them one by one. For simplicity, I've ignored dependency injection in this project. I have created another repository of MVP with dependency injection Dagger 2. You can check Android Weather App MVP Architecture with Dagger 2 repository from here.