Correctly deal with `Don't ask again`

android/app/src/main/java/io/github/sdlpal/MainActivity.java

@@ -21,9 +21,37 @@ public class MainActivity extends AppCompatActivity {
     public static boolean crashed = false;
 
     private final static int REQUEST_FILESYSTEM_ACCESS_CODE = 101;
+    private final AppCompatActivity mActivity = this;
 
-    private void requestForPermissions() {
-        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_FILESYSTEM_ACCESS_CODE);
+    private void requestForPermissions(boolean exitIfRequestForbidden) {
+        if (ActivityCompat.shouldShowRequestPermissionRationale(mActivity, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
+            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_FILESYSTEM_ACCESS_CODE);
+        } else {
+            if (exitIfRequestForbidden) {
+                System.exit(1);
+            } else {
+                alertUser();
+            }
+        }
+    }
+
+    private void alertUser() {
+        AlertDialog.Builder builder = new AlertDialog.Builder(this);
+        builder.setMessage(R.string.toast_requestpermission);
+        builder.setCancelable(false);
+        builder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+            @Override
+            public void onClick(DialogInterface dialogInterface, int i) {
+                requestForPermissions(true);
+            }
+        });
+        builder.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
+            @Override
+            public void onClick(DialogInterface dialogInterface, int i) {
+                System.exit(1);
+            }
+        });
+        builder.create().show();
     }
 
     @Override
@@ -34,22 +62,7 @@ public class MainActivity extends AppCompatActivity {
                 if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                     StartGame();
                 } else {
-                    AlertDialog.Builder builder = new AlertDialog.Builder(this);
-                    builder.setMessage(R.string.toast_requestpermission);
-                    builder.setCancelable(false);
-                    builder.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
-                        @Override
-                        public void onClick(DialogInterface dialogInterface, int i) {
-                            requestForPermissions();
-                        }
-                    });
-                    builder.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
-                        @Override
-                        public void onClick(DialogInterface dialogInterface, int i) {
-                            System.exit(1);
-                        }
-                    });
-                    builder.create().show();
+                    alertUser();
                 }
                 break;
         }
@@ -58,10 +71,11 @@ public class MainActivity extends AppCompatActivity {
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M || ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED)
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M || ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) {
             StartGame();
-        else
-            requestForPermissions();
+        } else {
+            requestForPermissions(false);
+        }
     }
 
     public void StartGame() {