request for location service is it not enabled to search for Bluetooth scales.

android_app/app/src/main/java/com/health/openscale/gui/preferences/BluetoothPreferences.java

@@ -232,8 +232,10 @@ public class BluetoothPreferences extends PreferenceFragment {
             @Override
             public boolean onPreferenceClick(Preference preference) {
                 if (PermissionHelper.requestBluetoothPermission(getActivity(), fragment)) {
+                    if (PermissionHelper.requestLocationServicePermission(getActivity())) {
                         startBluetoothDiscovery();
                     }
+                }
                 return true;
             }
         });

android_app/app/src/main/java/com/health/openscale/gui/utils/PermissionHelper.java

@@ -18,6 +18,7 @@ package com.health.openscale.gui.utils;
 import android.Manifest;
 import android.app.Activity;
 import android.app.AlertDialog;
+import android.app.Dialog;
 import android.app.Fragment;
 import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothManager;
@@ -25,11 +26,16 @@ import android.content.Context;
 import android.content.DialogInterface;
 import android.content.Intent;
 import android.content.pm.PackageManager;
-import androidx.core.app.ActivityCompat;
+import android.location.LocationManager;
+import android.provider.Settings;
 import android.widget.Toast;
 
 import com.health.openscale.R;
 
+import androidx.core.app.ActivityCompat;
+
+import static android.content.Context.LOCATION_SERVICE;
+
 public class PermissionHelper {
     public final static int PERMISSIONS_REQUEST_ACCESS_COARSE_LOCATION = 1;
     public final static int PERMISSIONS_REQUEST_ACCESS_READ_STORAGE = 2;
@@ -70,7 +76,34 @@ public class PermissionHelper {
                         }
                     });
 
-            builder.show();
+            Dialog alertDialog = builder.create();
+            alertDialog.setCanceledOnTouchOutside(false);
+            alertDialog.show();
+            return false;
+        }
+
+        return true;
+    }
+
+    public static boolean requestLocationServicePermission(final Activity activity) {
+        LocationManager locationManager = (LocationManager) activity.getSystemService(LOCATION_SERVICE);
+        if (!locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
+
+            AlertDialog.Builder builder = new AlertDialog.Builder(activity);
+            builder.setTitle(R.string.permission_bluetooth_info_title);
+            builder.setIcon(R.drawable.ic_preferences_about);
+            builder.setMessage(R.string.permission_location_service_info);
+            builder.setPositiveButton(R.string.label_ok, new DialogInterface.OnClickListener() {
+                public void onClick(DialogInterface dialogInterface, int i) {
+                    // Show location settings when the user acknowledges the alert dialog
+                    Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
+                    activity.startActivity(intent);
+                }
+            });
+
+            Dialog alertDialog = builder.create();
+            alertDialog.setCanceledOnTouchOutside(false);
+            alertDialog.show();
             return false;
         }
 

android_app/app/src/main/res/values/strings.xml

@@ -193,6 +193,7 @@
 
     <string name="permission_not_granted">Permission not granted</string>
     <string name="permission_bluetooth_info">Coarse location permission needed to search for Bluetooth devices. It can be revoked after the device is found.</string>
+    <string name="permission_location_service_info">Location Service (GPS) needs to be enabled to search for Bluetooth scale. Please enable it under Android settings.</string>
     <string name="permission_bluetooth_info_title">Info</string>
     <string name="permission_read_write_data_description">read/write openScale data, including user information and all saved measurements</string>
     <string name="permission_read_write_data_label">Read/Write openScale Data</string>