Android Weather App

This is a simple android weather application that fetches weather data from WeatherApi. It provides current hour data, hourly weather forecast, seven days weather forecast and city search. Selected city from city search result is saved in a shared preference to use the location as default weather location. By default city London, UK is selected.

Features

1. current weather report
2. hourly weather forecast
3. find and set weather location
4. 7 days weather forecast

Learning Outcome

• Storing Secret Information: For api calls we need api key. But this key should not be pushed to public repositories. Therefore, the right way to store and pass the apikey or any sensitive data during build time is adding it in local.properties in project root.

# local.properties
WEATHER_API_KEY=my-secret-key

Now to get this value during build time we add this in our module level BuildConfig.java. To do this open module level build.gradle add add these lines

android {
    
    // other configurations here
    
    def localProperties = new Property()
    def localPropertiesFile = rootProject.file('local.properties')
    if (localPropertiesFile.exists()) {
        localPropertiesFile.withReader('UTF-8') {
            localProperties.load(it)
        }
    }
    
    buildFeature {
        buildConfig = true // must add otherwise show warning
    }
    
    buildConfigField( // adds new field to the module level BuildConfig.java
            "String", // field type
            "WEATHER_KEY_API", // field name
            "\"${localProperties.getPerperty('WEATHER_API_KEY')}\"" // field value, for string must add double quote
    )
}

Next build the project to create the BuildConfig file. Since local.properties and BuildConfig.java both are ignored during git push so the sensitive data are safe. Note make sure in .gitignore at project root directory and local.properties is added.

• API call using Retrofit2: First of all I need to add the retrofit2 as well as one of the converters provided by Retrofit2 library. This converter is used serializing and deserializing the request and response. Like for this project gson converter is used so all the request body will be serialized to json and response body will be deserialized from json. During the retrofit build use addConverterFactory(...) method to add required converter.
• Request URL: Retrofit base url must end with / otherwise error occurs. Like this https://api.weatherapi.com/v1/. Also remember that if in service interface http method annotation, like GET POST etc., if / is prepended then path will be considered relative the domain part. So don't prepend / in service method url paths. For example: if @GET("/current.json") then requests to https://api.weatherapi.com/current.json not to https://api.weatherapi.com/v1/current.json .
• OkHttpClient Interceptor: In cases when I need to something for each request, then we can use OkHttpClient Interceptor interface to manipulate each request before sending. For example: this is project we need to append a key query which contains the api key value. I added an Interceptor that appends key query parameter to each request.
• Get ViewModel: using ViewModelProvider.get(Class) I can get and existing view model instance or create if not exists
• RecyclerView item click: to handle recyclerview item click i have used RecyclerView.OnItemTouchListener and GestureDetector. GestureDetector requires a OnGestureListener. This gesture listener provides different methods to handle different click events like single click, long click etc. finally an instance of OnItemTouchListener to be added to RecyclerView with addOnItemTouchListener

Change Log

• v2.0 4 features implemented

  1. city search and change current weather location
  2. detailed weather report for current hour
  3. hourly weather forecast for current date
  4. 7 days weather forecast for the current weather location

• v1.0 simple api call and display the current weather report for city London on success or log error body if request fails. If any other exception occurs then a Toast message is displayed.