feat: Get Maps API key from unversioned file instead of resource - kotlin (googlemaps-samples#189)

New process to add your own Google Maps API key:

1. [Get a Maps API key](https://developers.google.com/maps/documentation/android-sdk/get-api-key)
1. Create a file in the `ApiDemos/kotlin/app` directory called `secure.properties` (this file should *NOT* be under version control to protect your API key)
1. Add a single line to `ApiDemos/kotlin/app/secure.properties` that looks like `MAPS_API_KEY=YOUR_API_KEY`, where `YOUR_API_KEY` is the API key you obtained in the first step
1. Build and run

Author: barbeau

ApiDemos/kotlin/README.md

@@ -23,15 +23,18 @@ This sample use the Gradle build system.
 First download the samples by cloning this repository or downloading an archived
 snapshot. (See the options at the top of the page.)
 
-In Android Studio, use "Open an existing Android Studio project". Next select the ApiDemos/kotlin/ directory that you downloaded
+In Android Studio, use "Open an existing Android Studio project". Next select the `ApiDemos/kotlin/` directory that you downloaded
 from this repository.
 If prompted for a gradle configuration accept the default settings. 
 
-Alternatively use the "gradlew build" command to build the project directly.
+Alternatively use the `gradlew build` command to build the project directly.
 
-Add your API key to the file `debug/values/google_maps_api.xml`.
-It's pulled from there into your app's `AndroidManifest.xml` file.
-See the [quick guide to getting an API key](https://developers.google.com/maps/documentation/android-api/signup).
+This demo app requires that you add your own Google Maps API key:
+
+1. [Get a Maps API key](https://developers.google.com/maps/documentation/android-sdk/get-api-key)
+1. Create a file in the `ApiDemos/kotlin/app` directory called `secure.properties` (this file should *NOT* be under version control to protect your API key)
+1. Add a single line to `ApiDemos/kotlin/app/secure.properties` that looks like `MAPS_API_KEY=YOUR_API_KEY`, where `YOUR_API_KEY` is the API key you obtained in the first step
+1. Build and run
 
 Support
 -------

ApiDemos/kotlin/app/.gitignore

@@ -1 +1,2 @@
 /build
+secure.properties

ApiDemos/kotlin/app/build.gradle

@@ -13,6 +13,18 @@ android {
         versionCode 1
         versionName "1.0"
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+
+        // Read the API key from ApiDemos/kotlin/app/secure.properties into R.string.maps_api_key
+        def secureProps = new Properties()
+        if (file("secure.properties").exists()) {
+            file("secure.properties")?.withInputStream { secureProps.load(it) }
+        }
+        resValue "string", "maps_api_key", (secureProps.getProperty("MAPS_API_KEY") ?: "")
+
+        // To add your Maps API key to this project:
+        // 1. Create a file ApiDemos/kotlin/app/secure.properties
+        // 2. Add this line, where YOUR_API_KEY is your API key:
+        //        MAPS_API_KEY=YOUR_API_KEY
     }
     buildTypes {
         release {

ApiDemos/kotlin/app/src/debug/res/values/google_maps_api.xml

@@ -28,9 +28,15 @@
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/AppTheme">
+        <!--
+        To add your Maps API key to this project:
+            1. Create a file ApiDemos/kotlin/app/secure.properties
+            2. Add this line, where YOUR_API_KEY is your API key:
+                MAPS_API_KEY=YOUR_API_KEY
+        -->
         <meta-data
             android:name="com.google.android.geo.API_KEY"
-            android:value="@string/google_maps_key" />
+            android:value="@string/maps_api_key" />
         <activity android:name=".MainActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

ApiDemos/kotlin/app/src/main/AndroidManifest.xml

@@ -22,10 +22,7 @@ import android.content.Intent
 import android.os.Bundle
 import android.view.View
 import android.view.ViewGroup
-import android.widget.AdapterView
-import android.widget.ArrayAdapter
-import android.widget.ListAdapter
-import android.widget.ListView
+import android.widget.*
 import androidx.appcompat.app.AppCompatActivity
 
 /**
@@ -51,6 +48,11 @@ class MainActivity : AppCompatActivity(), AdapterView.OnItemClickListener {
             onItemClickListener = this@MainActivity
             emptyView = emptyMessage
         }
+
+        if (getString(R.string.maps_api_key).isEmpty()) {
+            Toast.makeText(this, "Add your own API key in ApiDemos/kotlin/app/secure.properties as MAPS_API_KEY=YOUR_API_KEY", Toast.LENGTH_LONG).show()
+        }
+
     }
 
     /**