[android] Fix gradle developer config creation task with discussed suggestions (#8897)

* fix gradle developer config creation task with discussed suggestions

* fix access token not set error message

platform/android/MapboxGLAndroidSDKTestApp/gradle-config.gradle

@@ -5,14 +5,15 @@
 task accessToken {
     def tokenFile = new File("${projectDir}/src/main/res/values/developer-config.xml")
     if (!tokenFile.exists()) {
+        String mapboxAccessToken = "$System.env.MAPBOX_ACCESS_TOKEN"
+        if (mapboxAccessToken == "null") {
+            System.out.println("You should set the MAPBOX_ACCESS_TOKEN environment variable.")
+            mapboxAccessToken = "YOUR_MAPBOX_ACCESS_TOKEN_GOES_HERE"
+        }
         String tokenFileContents = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n" +
                 "<resources>\n" +
-                "    <string name=\"mapbox_access_token\">" + "$System.env.MAPBOX_ACCESS_TOKEN" + "</string>\n" +
+                "    <string name=\"mapbox_access_token\">" + mapboxAccessToken + "</string>\n" +
                 "</resources>"
-
-        if (tokenFileContents == null) {
-            throw new InvalidUserDataException("You must set the MAPBOX_ACCESS_TOKEN environment variable.")
-        }
         tokenFile.write(tokenFileContents)
     }
 }

platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/MapboxApplication.java

@@ -2,8 +2,11 @@ package com.mapbox.mapboxsdk.testapp;
 
 import android.app.Application;
 import android.os.StrictMode;
+import android.text.TextUtils;
+import android.util.Log;
 
 import com.mapbox.mapboxsdk.Mapbox;
+import com.mapbox.mapboxsdk.testapp.utils.TokenUtils;
 import com.squareup.leakcanary.LeakCanary;
 
 import timber.log.Timber;
@@ -18,6 +21,13 @@ import static timber.log.Timber.DebugTree;
  */
 public class MapboxApplication extends Application {
 
+  private static final String LOG_TAG = MapboxApplication.class.getSimpleName();
+  private static final String DEFAULT_MAPBOX_ACCESS_TOKEN = "YOUR_MAPBOX_ACCESS_TOKEN_GOES_HERE";
+  private static final String ACCESS_TOKEN_NOT_SET_MESSAGE = "In order to run the Test App you need to set a valid "
+    + "access token. During development, you can set the MAPBOX_ACCESS_TOKEN environment variable for the SDK to "
+    + "automatically include it in the Test App. Otherwise, you can manually include it in the "
+    + "res/values/developer-config.xml file in the MapboxGLAndroidSDKTestApp folder.";
+
   @Override
   public void onCreate() {
     super.onCreate();
@@ -43,7 +53,12 @@ public class MapboxApplication extends Application {
       .penaltyDeath()
       .build());
 
-    Mapbox.getInstance(getApplicationContext(), getString(R.string.mapbox_access_token));
+    String mapboxAccessToken = TokenUtils.getMapboxAccessToken(getApplicationContext());
+    if (TextUtils.isEmpty(mapboxAccessToken) || mapboxAccessToken.equals(DEFAULT_MAPBOX_ACCESS_TOKEN)) {
+      Log.w(LOG_TAG, ACCESS_TOKEN_NOT_SET_MESSAGE);
+    }
+
+    Mapbox.getInstance(getApplicationContext(), mapboxAccessToken);
   }
 
   private void initializeLogger() {

platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/utils/TokenUtils.java

@@ -0,0 +1,37 @@
+package com.mapbox.mapboxsdk.testapp.utils;
+
+
+import android.content.Context;
+import android.support.annotation.NonNull;
+
+import com.mapbox.mapboxsdk.Mapbox;
+
+public class TokenUtils {
+
+  /**
+   * <p>
+   * Returns the Mapbox access token set in the app resources.
+   * </p>
+   * It will first search for a token in the Mapbox object. If not found it
+   * will then attempt to load the access token from the
+   * {@code res/values/dev.xml} development file.
+   *
+   * @param context The {@link Context} of the {@link android.app.Activity} or {@link android.app.Fragment}.
+   * @return The Mapbox access token or null if not found.
+   */
+  public static String getMapboxAccessToken(@NonNull Context context) {
+    try {
+      // Read out AndroidManifest
+      String token = Mapbox.getAccessToken();
+      if (token == null || token.isEmpty()) {
+        throw new IllegalArgumentException();
+      }
+      return token;
+    } catch (Exception exception) {
+      // Use fallback on string resource, used for development
+      int tokenResId = context.getResources()
+        .getIdentifier("mapbox_access_token", "string", context.getPackageName());
+      return tokenResId != 0 ? context.getString(tokenResId) : null;
+    }
+  }
+}