diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractGBFragment.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractGBFragment.java
index 6a77ae4d..8c2e770d 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractGBFragment.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractGBFragment.java
@@ -43,7 +43,7 @@ public abstract class AbstractGBFragment extends Fragment {
     }
 
     protected void updateActivityTitle() {
-        FragmentActivity activity = (FragmentActivity) getActivity();
+        FragmentActivity activity = getActivity();
         if (activity != null && !activity.isFinishing() && !activity.isDestroyed()) {
             if (getTitle() != null) {
                 activity.setTitle(getTitle());
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractSettingsActivity.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractSettingsActivity.java
index aca51f45..26ccfe0a 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractSettingsActivity.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/AbstractSettingsActivity.java
@@ -17,7 +17,7 @@ import org.slf4j.LoggerFactory;
  * to set that listener in #onCreate, *not* in #onPostCreate, otherwise the value will
  * not be displayed.
  */
-public class AbstractSettingsActivity extends PreferenceActivity {
+public abstract class AbstractSettingsActivity extends PreferenceActivity {
 
     private static final Logger LOG = LoggerFactory.getLogger(AbstractSettingsActivity.class);
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/ControlCenter.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/ControlCenter.java
index 92f13307..fa0a719c 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/ControlCenter.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/ControlCenter.java
@@ -27,7 +27,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/AbstractChartFragment.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/AbstractChartFragment.java
index 784d1cb6..254bb177 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/AbstractChartFragment.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/AbstractChartFragment.java
@@ -569,7 +569,7 @@ public abstract class AbstractChartFragment extends AbstractGBFragment {
         @Override
         protected void onPostExecute(Object o) {
             super.onPostExecute(o);
-            FragmentActivity activity = (FragmentActivity) getActivity();
+            FragmentActivity activity = getActivity();
             if (activity != null && !activity.isFinishing() && !activity.isDestroyed()) {
                 renderCharts();
             } else {
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsActivity.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsActivity.java
index e90ee1e8..58f4848b 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsActivity.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsActivity.java
@@ -10,9 +10,7 @@ import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.app.FragmentStatePagerAdapter;
 import android.support.v4.content.LocalBroadcastManager;
-import android.support.v4.view.PagerAdapter;
 import android.support.v4.view.PagerTabStrip;
-import android.support.v4.view.PagerTitleStrip;
 import android.support.v4.view.ViewPager;
 import android.support.v4.widget.SwipeRefreshLayout;
 import android.view.Menu;
@@ -27,7 +25,6 @@ import android.widget.Toast;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.lang.reflect.Method;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsHost.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsHost.java
index 06c9758d..543ed42e 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsHost.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/ChartsHost.java
@@ -7,9 +7,9 @@ import java.util.Date;
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
 
 public interface ChartsHost {
-    static final String DATE_PREV = ChartsActivity.class.getName().concat(".date_prev");
-    static final String DATE_NEXT = ChartsActivity.class.getName().concat(".date_next");
-    static final String REFRESH = ChartsActivity.class.getName().concat(".refresh");
+    String DATE_PREV = ChartsActivity.class.getName().concat(".date_prev");
+    String DATE_NEXT = ChartsActivity.class.getName().concat(".date_next");
+    String REFRESH = ChartsActivity.class.getName().concat(".refresh");
 
     GBDevice getDevice();
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SingleEntryValueAnimator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SingleEntryValueAnimator.java
index 2a48882d..3655f3ba 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SingleEntryValueAnimator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SingleEntryValueAnimator.java
@@ -1,6 +1,5 @@
 package nodomain.freeyourgadget.gadgetbridge.activities.charts;
 
-import android.animation.Animator;
 import android.animation.ObjectAnimator;
 import android.animation.ValueAnimator;
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SleepUtils.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SleepUtils.java
index 9926656d..58782bf8 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SleepUtils.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/charts/SleepUtils.java
@@ -6,7 +6,7 @@ public class SleepUtils {
     public static final float Y_VALUE_DEEP_SLEEP = 0.01f;
     public static final float Y_VALUE_LIGHT_SLEEP = 0.016f;
 
-    public static final boolean isSleep(byte type) {
+    public static boolean isSleep(byte type) {
         return type == ActivityKind.TYPE_DEEP_SLEEP || type == ActivityKind.TYPE_LIGHT_SLEEP;
     }
 }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/adapter/GBAlarmListAdapter.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/adapter/GBAlarmListAdapter.java
index cc60346f..55b197bb 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/adapter/GBAlarmListAdapter.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/adapter/GBAlarmListAdapter.java
@@ -40,7 +40,7 @@ public class GBAlarmListAdapter extends ArrayAdapter<GBAlarm> {
         super(context, 0, new ArrayList<GBAlarm>());
 
         this.mContext = context;
-        alarmList = new ArrayList<GBAlarm>();
+        alarmList = new ArrayList<>();
 
         for (String alarmString : preferencesAlarmListSet) {
             alarmList.add(new GBAlarm(alarmString));
@@ -50,7 +50,7 @@ public class GBAlarmListAdapter extends ArrayAdapter<GBAlarm> {
     }
 
     public void setAlarmList(Set<String> preferencesAlarmListSet) {
-        alarmList = new ArrayList<GBAlarm>();
+        alarmList = new ArrayList<>();
 
         for (String alarmString : preferencesAlarmListSet) {
             alarmList.add(new GBAlarm(alarmString));
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/database/ActivityDatabaseHandler.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/database/ActivityDatabaseHandler.java
index ded7db21..d0263b57 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/database/ActivityDatabaseHandler.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/database/ActivityDatabaseHandler.java
@@ -202,7 +202,7 @@ public class ActivityDatabaseHandler extends SQLiteOpenHelper implements DBHandl
         if (timestamp_from < 0) {
             throw new IllegalArgumentException("negative timestamp_from");
         }
-        ArrayList<ActivitySample> samples = new ArrayList<ActivitySample>();
+        ArrayList<ActivitySample> samples = new ArrayList<>();
         final String where = "(provider=" + provider.getID() + " and timestamp>=" + timestamp_from + " and timestamp<=" + timestamp_to + getWhereClauseFor(activityTypes, provider) + ")";
         LOG.info("Activity query where: " + where);
         final String order = "timestamp";
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/AbstractDeviceCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/AbstractDeviceCoordinator.java
index b157d22f..28e5fcf8 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/AbstractDeviceCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/AbstractDeviceCoordinator.java
@@ -1,7 +1,6 @@
 package nodomain.freeyourgadget.gadgetbridge.devices;
 
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
-import nodomain.freeyourgadget.gadgetbridge.util.DeviceHelper;
 
 public abstract class AbstractDeviceCoordinator implements DeviceCoordinator {
     public boolean allowFetchActivityData(GBDevice device) {
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/InstallHandler.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/InstallHandler.java
index c2d152da..1314dc0e 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/InstallHandler.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/InstallHandler.java
@@ -13,7 +13,7 @@ public interface InstallHandler {
      * Returns true if this handler is able to install the element.
      * #validateInstallation may only be called if this method returned true.
      */
-    public boolean isValid();
+    boolean isValid();
 
     /**
      * Checks whether the installation of the 'element' on the device is possible
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandCoordinator.java
index 6e9a495b..20c9d4af 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandCoordinator.java
@@ -14,7 +14,6 @@ import java.util.Calendar;
 import nodomain.freeyourgadget.gadgetbridge.GBApplication;
 import nodomain.freeyourgadget.gadgetbridge.activities.charts.ChartsActivity;
 import nodomain.freeyourgadget.gadgetbridge.devices.AbstractDeviceCoordinator;
-import nodomain.freeyourgadget.gadgetbridge.devices.DeviceCoordinator;
 import nodomain.freeyourgadget.gadgetbridge.devices.InstallHandler;
 import nodomain.freeyourgadget.gadgetbridge.devices.SampleProvider;
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandFWHelper.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandFWHelper.java
index c2d9cd0c..e3c0ece4 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandFWHelper.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandFWHelper.java
@@ -45,6 +45,9 @@ public class MiBandFWHelper {
     public MiBandFWHelper(Uri uri, Context context) throws IOException {
         this.uri = uri;
         cr = context.getContentResolver();
+        if (cr == null) {
+            throw new IOException("No content resolver");
+        }
 
         String pebblePattern = ".*\\.(pbw|pbz|pbl)";
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandService.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandService.java
index 84a72732..6ce3e26e 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandService.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/miband/MiBandService.java
@@ -4,9 +4,6 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.UUID;
 
-import nodomain.freeyourgadget.gadgetbridge.service.btle.GattCharacteristic;
-import nodomain.freeyourgadget.gadgetbridge.service.btle.GattService;
-
 import static nodomain.freeyourgadget.gadgetbridge.service.btle.AbstractBTLEDeviceSupport.BASE_UUID;
 
 public class MiBandService {
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PBWReader.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PBWReader.java
index 4e00aa13..4025ca08 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PBWReader.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PBWReader.java
@@ -32,7 +32,7 @@ public class PBWReader {
     private static final HashMap<String, Byte> appFileTypesMap;
 
     static {
-        appFileTypesMap = new HashMap<String, Byte>();
+        appFileTypesMap = new HashMap<>();
         appFileTypesMap.put("application", PebbleProtocol.PUTBYTES_TYPE_BINARY);
         appFileTypesMap.put("resources", PebbleProtocol.PUTBYTES_TYPE_RESOURCES);
         appFileTypesMap.put("worker", PebbleProtocol.PUTBYTES_TYPE_WORKER);
@@ -41,7 +41,7 @@ public class PBWReader {
     private static final HashMap<String, Byte> fwFileTypesMap;
 
     static {
-        fwFileTypesMap = new HashMap<String, Byte>();
+        fwFileTypesMap = new HashMap<>();
         fwFileTypesMap.put("firmware", PebbleProtocol.PUTBYTES_TYPE_FIRMWARE);
         fwFileTypesMap.put("resources", PebbleProtocol.PUTBYTES_TYPE_SYSRESOURCES);
     }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PebbleCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PebbleCoordinator.java
index 18ac6e76..80450f72 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PebbleCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/pebble/PebbleCoordinator.java
@@ -9,7 +9,6 @@ import android.preference.PreferenceManager;
 import nodomain.freeyourgadget.gadgetbridge.GBApplication;
 import nodomain.freeyourgadget.gadgetbridge.activities.AppManagerActivity;
 import nodomain.freeyourgadget.gadgetbridge.devices.AbstractDeviceCoordinator;
-import nodomain.freeyourgadget.gadgetbridge.devices.DeviceCoordinator;
 import nodomain.freeyourgadget.gadgetbridge.devices.InstallHandler;
 import nodomain.freeyourgadget.gadgetbridge.devices.SampleProvider;
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/externalevents/K9Receiver.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/externalevents/K9Receiver.java
index c8bf1cd9..281e0052 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/externalevents/K9Receiver.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/externalevents/K9Receiver.java
@@ -55,17 +55,24 @@ public class K9Receiver extends BroadcastReceiver {
          * It should be the first one returned by the query in most cases,
          */
         Cursor c = context.getContentResolver().query(k9Uri, messagesProjection, null, null, null);
-        c.moveToFirst();
-        do {
-            String uri = c.getString(c.getColumnIndex("uri"));
-            if (uri.equals(uriWanted)) {
-                notificationSpec.sender = c.getString(c.getColumnIndex("senderAddress"));
-                notificationSpec.subject = c.getString(c.getColumnIndex("subject"));
-                notificationSpec.body = c.getString(c.getColumnIndex("preview"));
-                break;
+        try {
+            if (c != null) {
+                c.moveToFirst();
+                do {
+                    String uri = c.getString(c.getColumnIndex("uri"));
+                    if (uri.equals(uriWanted)) {
+                        notificationSpec.sender = c.getString(c.getColumnIndex("senderAddress"));
+                        notificationSpec.subject = c.getString(c.getColumnIndex("subject"));
+                        notificationSpec.body = c.getString(c.getColumnIndex("preview"));
+                        break;
+                    }
+                } while (c.moveToNext());
             }
-        } while (c.moveToNext());
-        c.close();
+        } finally {
+            if (c != null) {
+                c.close();
+            }
+        }
 
         GBApplication.deviceService().onNotification(notificationSpec);
     }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/impl/GBAlarm.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/impl/GBAlarm.java
index 93041fc1..bca028cd 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/impl/GBAlarm.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/impl/GBAlarm.java
@@ -190,7 +190,7 @@ public class GBAlarm implements Alarm {
         SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(GBApplication.getContext());
         Set<String> preferencesAlarmListSet = sharedPrefs.getStringSet(PREF_MIBAND_ALARMS, new HashSet<String>());
         //the old Set cannot be updated in place see http://developer.android.com/reference/android/content/SharedPreferences.html#getStringSet%28java.lang.String,%20java.util.Set%3Cjava.lang.String%3E%29
-        Set<String> newPrefs = new HashSet<String>(preferencesAlarmListSet);
+        Set<String> newPrefs = new HashSet<>(preferencesAlarmListSet);
 
         Iterator<String> iterator = newPrefs.iterator();
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/Alarm.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/Alarm.java
index d1ebb44c..01adde47 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/Alarm.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/Alarm.java
@@ -5,14 +5,14 @@ import android.os.Parcelable;
 import java.util.Calendar;
 
 public interface Alarm extends Parcelable, Comparable<Alarm> {
-    public static final byte ALARM_ONCE = 0;
-    public static final byte ALARM_MON = 1;
-    public static final byte ALARM_TUE = 2;
-    public static final byte ALARM_WED = 4;
-    public static final byte ALARM_THU = 8;
-    public static final byte ALARM_FRI = 16;
-    public static final byte ALARM_SAT = 32;
-    public static final byte ALARM_SUN = 64;
+    byte ALARM_ONCE = 0;
+    byte ALARM_MON = 1;
+    byte ALARM_TUE = 2;
+    byte ALARM_WED = 4;
+    byte ALARM_THU = 8;
+    byte ALARM_FRI = 16;
+    byte ALARM_SAT = 32;
+    byte ALARM_SUN = 64;
 
     int getIndex();
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/DeviceService.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/DeviceService.java
index 6a2c54d6..59a09f20 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/DeviceService.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/DeviceService.java
@@ -9,52 +9,52 @@ import nodomain.freeyourgadget.gadgetbridge.service.DeviceCommunicationService;
  *
  */
 public interface DeviceService extends EventHandler {
-    static final String PREFIX = "nodomain.freeyourgadget.gadgetbridge.devices";
+    String PREFIX = "nodomain.freeyourgadget.gadgetbridge.devices";
 
-    static final String ACTION_START = PREFIX + ".action.start";
-    static final String ACTION_CONNECT = PREFIX + ".action.connect";
-    static final String ACTION_NOTIFICATION = PREFIX + ".action.notification";
-    static final String ACTION_NOTIFICATION_SMS = PREFIX + ".action.notification_sms";
-    static final String ACTION_CALLSTATE = PREFIX + ".action.callstate";
-    static final String ACTION_SETTIME = PREFIX + ".action.settime";
-    static final String ACTION_SETMUSICINFO = PREFIX + ".action.setmusicinfo";
-    static final String ACTION_REQUEST_DEVICEINFO = PREFIX + ".action.request_deviceinfo";
-    static final String ACTION_REQUEST_APPINFO = PREFIX + ".action.request_appinfo";
-    static final String ACTION_REQUEST_SCREENSHOT = PREFIX + ".action.request_screenshot";
-    static final String ACTION_STARTAPP = PREFIX + ".action.startapp";
-    static final String ACTION_DELETEAPP = PREFIX + ".action.deleteapp";
-    static final String ACTION_INSTALL = PREFIX + ".action.install";
-    static final String ACTION_REBOOT = PREFIX + ".action.reboot";
-    static final String ACTION_FETCH_ACTIVITY_DATA = PREFIX + ".action.fetch_activity_data";
-    static final String ACTION_DISCONNECT = PREFIX + ".action.disconnect";
-    static final String ACTION_FIND_DEVICE = PREFIX + ".action.find_device";
-    static final String ACTION_SET_ALARMS = PREFIX + ".action.set_alarms";
-    static final String ACTION_ENABLE_REALTIME_STEPS = PREFIX + ".action.enable_realtime_steps";
-    static final String ACTION_REALTIME_STEPS = PREFIX + ".action.realtime_steps";
+    String ACTION_START = PREFIX + ".action.start";
+    String ACTION_CONNECT = PREFIX + ".action.connect";
+    String ACTION_NOTIFICATION = PREFIX + ".action.notification";
+    String ACTION_NOTIFICATION_SMS = PREFIX + ".action.notification_sms";
+    String ACTION_CALLSTATE = PREFIX + ".action.callstate";
+    String ACTION_SETTIME = PREFIX + ".action.settime";
+    String ACTION_SETMUSICINFO = PREFIX + ".action.setmusicinfo";
+    String ACTION_REQUEST_DEVICEINFO = PREFIX + ".action.request_deviceinfo";
+    String ACTION_REQUEST_APPINFO = PREFIX + ".action.request_appinfo";
+    String ACTION_REQUEST_SCREENSHOT = PREFIX + ".action.request_screenshot";
+    String ACTION_STARTAPP = PREFIX + ".action.startapp";
+    String ACTION_DELETEAPP = PREFIX + ".action.deleteapp";
+    String ACTION_INSTALL = PREFIX + ".action.install";
+    String ACTION_REBOOT = PREFIX + ".action.reboot";
+    String ACTION_FETCH_ACTIVITY_DATA = PREFIX + ".action.fetch_activity_data";
+    String ACTION_DISCONNECT = PREFIX + ".action.disconnect";
+    String ACTION_FIND_DEVICE = PREFIX + ".action.find_device";
+    String ACTION_SET_ALARMS = PREFIX + ".action.set_alarms";
+    String ACTION_ENABLE_REALTIME_STEPS = PREFIX + ".action.enable_realtime_steps";
+    String ACTION_REALTIME_STEPS = PREFIX + ".action.realtime_steps";
 
-    static final String EXTRA_DEVICE_ADDRESS = "device_address";
-    static final String EXTRA_NOTIFICATION_BODY = "notification_body";
-    static final String EXTRA_NOTIFICATION_ID = "notification_id";
-    static final String EXTRA_NOTIFICATION_PHONENUMBER = "notification_phonenumber";
-    static final String EXTRA_NOTIFICATION_SENDER = "notification_sender";
-    static final String EXTRA_NOTIFICATION_SOURCENAME = "notification_sourcename";
-    static final String EXTRA_NOTIFICATION_SUBJECT = "notification_subject";
-    static final String EXTRA_NOTIFICATION_TITLE = "notification_title";
-    static final String EXTRA_NOTIFICATION_TYPE = "notification_type";
-    static final String EXTRA_FIND_START = "find_start";
-    static final String EXTRA_CALL_COMMAND = "call_command";
-    static final String EXTRA_CALL_PHONENUMBER = "call_phonenumber";
-    static final String EXTRA_MUSIC_ARTIST = "music_artist";
-    static final String EXTRA_MUSIC_ALBUM = "music_album";
-    static final String EXTRA_MUSIC_TRACK = "music_track";
-    static final String EXTRA_APP_UUID = "app_uuid";
-    static final String EXTRA_APP_START = "app_start";
-    static final String EXTRA_URI = "uri";
-    static final String EXTRA_ALARMS = "alarms";
-    static final String EXTRA_PERFORM_PAIR = "perform_pair";
-    static final String EXTRA_ENABLE_REALTIME_STEPS = "enable_realtime_steps";
-    static final String EXTRA_REALTIME_STEPS = "realtime_steps";
-    static final String EXTRA_TIMESTAMP = "timestamp";
+    String EXTRA_DEVICE_ADDRESS = "device_address";
+    String EXTRA_NOTIFICATION_BODY = "notification_body";
+    String EXTRA_NOTIFICATION_ID = "notification_id";
+    String EXTRA_NOTIFICATION_PHONENUMBER = "notification_phonenumber";
+    String EXTRA_NOTIFICATION_SENDER = "notification_sender";
+    String EXTRA_NOTIFICATION_SOURCENAME = "notification_sourcename";
+    String EXTRA_NOTIFICATION_SUBJECT = "notification_subject";
+    String EXTRA_NOTIFICATION_TITLE = "notification_title";
+    String EXTRA_NOTIFICATION_TYPE = "notification_type";
+    String EXTRA_FIND_START = "find_start";
+    String EXTRA_CALL_COMMAND = "call_command";
+    String EXTRA_CALL_PHONENUMBER = "call_phonenumber";
+    String EXTRA_MUSIC_ARTIST = "music_artist";
+    String EXTRA_MUSIC_ALBUM = "music_album";
+    String EXTRA_MUSIC_TRACK = "music_track";
+    String EXTRA_APP_UUID = "app_uuid";
+    String EXTRA_APP_START = "app_start";
+    String EXTRA_URI = "uri";
+    String EXTRA_ALARMS = "alarms";
+    String EXTRA_PERFORM_PAIR = "perform_pair";
+    String EXTRA_ENABLE_REALTIME_STEPS = "enable_realtime_steps";
+    String EXTRA_REALTIME_STEPS = "realtime_steps";
+    String EXTRA_TIMESTAMP = "timestamp";
 
     void start();
 
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/SummaryOfDay.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/SummaryOfDay.java
index e656c382..009b94f1 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/SummaryOfDay.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/model/SummaryOfDay.java
@@ -1,12 +1,12 @@
 package nodomain.freeyourgadget.gadgetbridge.model;
 
 public interface SummaryOfDay {
-    public byte getProvider();
+    byte getProvider();
 
-    public int getSteps();
+    int getSteps();
 
-    public int getDayStartWakeupTime();
+    int getDayStartWakeupTime();
 
-    public int getDayEndFallAsleepTime();
+    int getDayEndFallAsleepTime();
 
 }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/AbstractDeviceSupport.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/AbstractDeviceSupport.java
index ec2b8f20..f1d7f7b9 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/AbstractDeviceSupport.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/AbstractDeviceSupport.java
@@ -248,7 +248,7 @@ public abstract class AbstractDeviceSupport implements DeviceSupport {
             GB.updateBatteryNotification(context.getString(R.string.notif_battery_low_percent, gbDevice.getName(), deviceEvent.level),
                     deviceEvent.extendedInfoAvailable() ?
                             context.getString(R.string.notif_battery_low_percent, gbDevice.getName(), deviceEvent.level) + "\n" +
-                                    context.getString(R.string.notif_battery_low_bigtext_last_charge_time, DateFormat.getDateTimeInstance().format(deviceEvent.lastChargeTime.getTime()).toString()) +
+                                    context.getString(R.string.notif_battery_low_bigtext_last_charge_time, DateFormat.getDateTimeInstance().format(deviceEvent.lastChargeTime.getTime())) +
                                     context.getString(R.string.notif_battery_low_bigtext_number_of_charges, deviceEvent.numCharges)
                             : ""
                     , context);
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/ServiceDeviceSupport.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/ServiceDeviceSupport.java
index cd9718b4..b75b1c59 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/ServiceDeviceSupport.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/ServiceDeviceSupport.java
@@ -21,7 +21,7 @@ import nodomain.freeyourgadget.gadgetbridge.model.ServiceCommand;
  */
 public class ServiceDeviceSupport implements DeviceSupport {
 
-    static enum Flags {
+    enum Flags {
         THROTTLING,
         BUSY_CHECKING,
     }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BTLEOperation.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BTLEOperation.java
index f1c57d3d..03d1f923 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BTLEOperation.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BTLEOperation.java
@@ -3,5 +3,5 @@ package nodomain.freeyourgadget.gadgetbridge.service.btle;
 import java.io.IOException;
 
 public interface BTLEOperation {
-    public void perform() throws IOException;
+    void perform() throws IOException;
 }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BtLEQueue.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BtLEQueue.java
index 4c9ac90c..d97ac8c8 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BtLEQueue.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/BtLEQueue.java
@@ -30,7 +30,7 @@ import nodomain.freeyourgadget.gadgetbridge.service.DeviceSupport;
 public final class BtLEQueue {
     private static final Logger LOG = LoggerFactory.getLogger(BtLEQueue.class);
 
-    private Object mGattMonitor = new Object();
+    private final Object mGattMonitor = new Object();
     private GBDevice mGbDevice;
     private BluetoothAdapter mBluetoothAdapter;
     private BluetoothGatt mBluetoothGatt;
@@ -41,7 +41,7 @@ public final class BtLEQueue {
 
     private static final long MIN_MILLIS_BEFORE_RECONNECT = 1000 * 60 * 5; // 5 minutes
 
-    private volatile BlockingQueue<Transaction> mTransactions = new LinkedBlockingQueue<Transaction>();
+    private volatile BlockingQueue<Transaction> mTransactions = new LinkedBlockingQueue<>();
     private volatile boolean mDisposed;
     private volatile boolean mCrashed;
     private volatile boolean mAbortTransaction;
@@ -460,7 +460,7 @@ public final class BtLEQueue {
                 }
             } else {
                 if (BtLEQueue.this.mWaitCharacteristic != null) {
-                    LOG.error("checkWaitingCharacteristic: mismatched characteristic received: " + characteristic != null ? characteristic.getUuid().toString() : "(null)");
+                    LOG.error("checkWaitingCharacteristic: mismatched characteristic received: " + ((characteristic != null && characteristic.getUuid() != null) ? characteristic.getUuid().toString() : "(null)"));
                 }
             }
         }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/GattCallback.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/GattCallback.java
index f5105b06..ec5afed5 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/GattCallback.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/GattCallback.java
@@ -73,7 +73,7 @@ public interface GattCallback {
      * @param status
      * @see BluetoothGattCallback#onDescriptorRead(BluetoothGatt, BluetoothGattDescriptor, int)
      */
-    public void onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor,
+    void onDescriptorRead(BluetoothGatt gatt, BluetoothGattDescriptor descriptor,
                                  int status);
 
     /**
@@ -82,7 +82,7 @@ public interface GattCallback {
      * @param status
      * @see BluetoothGattCallback#onDescriptorWrite(BluetoothGatt, BluetoothGattDescriptor, int)
      */
-    public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor,
+    void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor,
                                   int status);
 //
 //    /**
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/actions/NotifyAction.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/actions/NotifyAction.java
index 61543bb3..79773031 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/actions/NotifyAction.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/btle/actions/NotifyAction.java
@@ -4,7 +4,6 @@ import android.bluetooth.BluetoothGatt;
 import android.bluetooth.BluetoothGattCallback;
 import android.bluetooth.BluetoothGattCharacteristic;
 import android.bluetooth.BluetoothGattDescriptor;
-import android.bluetooth.BluetoothGattService;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/DeviceInfo.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/DeviceInfo.java
index 67d0845c..0b3e8c0e 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/DeviceInfo.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/DeviceInfo.java
@@ -4,8 +4,6 @@ import nodomain.freeyourgadget.gadgetbridge.GBApplication;
 import nodomain.freeyourgadget.gadgetbridge.R;
 import nodomain.freeyourgadget.gadgetbridge.util.CheckSums;
 
-import java.util.Locale;
-
 public class DeviceInfo extends AbstractInfo {
     public final String deviceId;
     public final int profileVersion;
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/MiBandSupport.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/MiBandSupport.java
index 00ec89a9..832957fd 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/MiBandSupport.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/MiBandSupport.java
@@ -9,8 +9,6 @@ import android.preference.PreferenceManager;
 import android.support.v4.content.LocalBroadcastManager;
 import android.widget.Toast;
 
-import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandFWHelper;
-import nodomain.freeyourgadget.gadgetbridge.service.btle.actions.WriteAction;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -28,6 +26,7 @@ import nodomain.freeyourgadget.gadgetbridge.deviceevents.GBDeviceEventVersionInf
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandConst;
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandCoordinator;
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandDateConverter;
+import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandFWHelper;
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandService;
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.VibrationProfile;
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice.State;
@@ -35,7 +34,6 @@ import nodomain.freeyourgadget.gadgetbridge.model.Alarm;
 import nodomain.freeyourgadget.gadgetbridge.model.DeviceService;
 import nodomain.freeyourgadget.gadgetbridge.model.NotificationSpec;
 import nodomain.freeyourgadget.gadgetbridge.model.ServiceCommand;
-import nodomain.freeyourgadget.gadgetbridge.service.DeviceSupport;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.AbstractBTLEDeviceSupport;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.BtLEAction;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.GattCharacteristic;
@@ -43,6 +41,7 @@ import nodomain.freeyourgadget.gadgetbridge.service.btle.GattService;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.TransactionBuilder;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.actions.AbortTransactionAction;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.actions.SetDeviceStateAction;
+import nodomain.freeyourgadget.gadgetbridge.service.btle.actions.WriteAction;
 import nodomain.freeyourgadget.gadgetbridge.service.devices.miband.operations.FetchActivityOperation;
 import nodomain.freeyourgadget.gadgetbridge.service.devices.miband.operations.UpdateFirmwareOperation;
 import nodomain.freeyourgadget.gadgetbridge.util.DateTimeUtils;
@@ -712,7 +711,7 @@ public class MiBandSupport extends AbstractBTLEDeviceSupport {
         byte[] alarmCalBytes = MiBandDateConverter.calendarToRawBytes(alarm.getAlarmCal());
 
         byte[] alarmMessage = new byte[]{
-                (byte) MiBandService.COMMAND_SET_TIMER,
+                MiBandService.COMMAND_SET_TIMER,
                 (byte) alarm.getIndex(),
                 (byte) (alarm.isEnabled() ? 1 : 0),
                 alarmCalBytes[0],
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/NotificationStrategy.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/NotificationStrategy.java
index 34e538fb..1007f7ce 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/NotificationStrategy.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/miband/NotificationStrategy.java
@@ -1,15 +1,11 @@
 package nodomain.freeyourgadget.gadgetbridge.service.devices.miband;
 
-import android.bluetooth.BluetoothGattCharacteristic;
-
-import nodomain.freeyourgadget.gadgetbridge.devices.miband.MiBandService;
 import nodomain.freeyourgadget.gadgetbridge.devices.miband.VibrationProfile;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.BtLEAction;
-import nodomain.freeyourgadget.gadgetbridge.service.btle.GattCharacteristic;
 import nodomain.freeyourgadget.gadgetbridge.service.btle.TransactionBuilder;
 
 public interface NotificationStrategy {
-    public void sendDefaultNotification(TransactionBuilder builder, BtLEAction extraAction);
+    void sendDefaultNotification(TransactionBuilder builder, BtLEAction extraAction);
 
     /**
      * Adds a custom notification to the given transaction builder
@@ -22,5 +18,5 @@ public interface NotificationStrategy {
      * @param extraAction      an extra action to be executed after every vibration and flash sequence. Allows to abort the repetition, for example.
      * @param builder
      */
-    public void sendCustomNotification(VibrationProfile vibrationProfile, int flashTimes, int flashColour, int originalColour, long flashDuration, BtLEAction extraAction, TransactionBuilder builder);
+    void sendCustomNotification(VibrationProfile vibrationProfile, int flashTimes, int flashColour, int originalColour, long flashDuration, BtLEAction extraAction, TransactionBuilder builder);
 }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/pebble/PebbleProtocol.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/pebble/PebbleProtocol.java
index 2f33b66c..2c1a2a40 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/pebble/PebbleProtocol.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/pebble/PebbleProtocol.java
@@ -1178,7 +1178,7 @@ public class PebbleProtocol extends GBDeviceProtocol {
     }
 
     private ArrayList<Pair<Integer, Object>> decodeDict(ByteBuffer buf) {
-        ArrayList<Pair<Integer, Object>> dict = new ArrayList<Pair<Integer, Object>>();
+        ArrayList<Pair<Integer, Object>> dict = new ArrayList<>();
         buf.order(ByteOrder.LITTLE_ENDIAN);
         byte dictSize = buf.get();
         while (dictSize-- > 0) {
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/receivers/GBMusicControlReceiver.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/receivers/GBMusicControlReceiver.java
index 8a521679..fce01765 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/receivers/GBMusicControlReceiver.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/receivers/GBMusicControlReceiver.java
@@ -69,9 +69,7 @@ public class GBMusicControlReceiver extends BroadcastReceiver {
             Intent upIntent = new Intent(Intent.ACTION_MEDIA_BUTTON, null);
             KeyEvent upEvent = new KeyEvent(eventtime, eventtime, KeyEvent.ACTION_UP, keyCode, 0);
             upIntent.putExtra(Intent.EXTRA_KEY_EVENT, upEvent);
-            if (audioPlayer != null) {
-                upIntent.setPackage(audioPlayer);
-            }
+            upIntent.setPackage(audioPlayer);
             context.sendOrderedBroadcast(upIntent, null);
         }
     }
diff --git a/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/DeviceCommunicationServiceTestCase.java b/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/DeviceCommunicationServiceTestCase.java
index f32f6f9b..394ff8ba 100644
--- a/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/DeviceCommunicationServiceTestCase.java
+++ b/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/DeviceCommunicationServiceTestCase.java
@@ -2,7 +2,6 @@ package nodomain.freeyourgadget.gadgetbridge.service;
 
 import android.content.Context;
 
-import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.InOrder;
diff --git a/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/TestDeviceSupport.java b/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/TestDeviceSupport.java
index 2538af60..208af61b 100644
--- a/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/TestDeviceSupport.java
+++ b/app/src/test/java/nodomain/freeyourgadget/gadgetbridge/service/TestDeviceSupport.java
@@ -11,10 +11,8 @@ import java.util.UUID;
 import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
 import nodomain.freeyourgadget.gadgetbridge.model.Alarm;
 import nodomain.freeyourgadget.gadgetbridge.model.DeviceType;
-import nodomain.freeyourgadget.gadgetbridge.model.ServiceCommand;
-import nodomain.freeyourgadget.gadgetbridge.model.NotificationType;
 import nodomain.freeyourgadget.gadgetbridge.model.NotificationSpec;
-import nodomain.freeyourgadget.gadgetbridge.service.AbstractDeviceSupport;
+import nodomain.freeyourgadget.gadgetbridge.model.ServiceCommand;
 
 public class TestDeviceSupport extends AbstractDeviceSupport {