How to use API KEY in the Adnroid app

How to Hide & Protect API Keys in Your Android App.

1. Get a Maps API key.
2. Create a file in the root directory of your project called secure.properties (this file should NOT be under version control to protect your API key)
3. Add a single line to secure.properties that looks like: API_KEY=YOUR_API_KEY, where YOUR_API_KEY is the API key you obtained in the first step.
4. Put following code into your module build.gradle file:
   

   android {
     ...
     defaultConfig {
       ...
         def secureProps = new Properties()
         def securePropsFile = rootProject.file("secure.properties")
         if (securePropsFile.exists()) secureProps.load(new FileInputStream(securePropsFile))
         resValue "string", "api_key", (secureProps.getProperty("API_KEY") ?: "")
       ...

5. Use api_key in your Manifest:

   <meta-data
     android:name="com.google.android.geo.API_KEY"
     android:value="@string/api_key" />

6. Your API KEY can be accessed at runtime using the statement: getString(R.string.api_key)
7. Build and run