Bugfix: prevent NPE as handler should not be executed anymore.

Fixes #1035.

src/main/java/de/dennisguse/opentracks/ControllerFragment.java

@@ -17,6 +17,7 @@
 package de.dennisguse.opentracks;
 
 import android.annotation.SuppressLint;
+import android.content.Context;
 import android.graphics.drawable.TransitionDrawable;
 import android.os.Bundle;
 import android.os.Handler;
@@ -97,7 +98,10 @@ public class ControllerFragment extends Fragment implements View.OnTouchListener
                 return;
             }
 
-            getCallback().recordStart();
+            Callback callback = (Callback) getContext();
+            if (callback != null) {
+                callback.recordStart();
+            }
         });
 
         viewBinding.controllerStop.setOnTouchListener(this);
@@ -114,6 +118,12 @@ public class ControllerFragment extends Fragment implements View.OnTouchListener
         trackRecordingServiceConnection.startConnection(getContext());
     }
 
+    @Override
+    public void onPause() {
+        super.onPause();
+        handlerUpdateTotalTime.removeCallbacksAndMessages(null);
+    }
+
     @Override
     public void onStop() {
         super.onStop();
@@ -175,7 +185,10 @@ public class ControllerFragment extends Fragment implements View.OnTouchListener
             buttonDelay = () -> {
                 view.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
                 view.performClick();
-                getCallback().recordPause();
+                Callback callback = (Callback) getContext();
+                if (callback != null) {
+                    callback.recordPause();
+                }
 
                 transition.resetTransition();
 
@@ -198,8 +211,12 @@ public class ControllerFragment extends Fragment implements View.OnTouchListener
 
             buttonDelay = () -> {
                 view.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);
-                getCallback().recordStop();
+                Context context = getContext();
-                ActivityUtils.vibrate(getContext(), 1000);
+                Callback callback = (Callback) context;
+                if (callback != null) {
+                    callback.recordStop();
+                    ActivityUtils.vibrate(context, 1000);
+                }
 
                 transition.resetTransition();
             };
@@ -222,10 +239,6 @@ public class ControllerFragment extends Fragment implements View.OnTouchListener
         viewBinding.controllerStatus.setText(recordingStatus.isPaused() ? R.string.generic_paused : R.string.generic_recording);
     }
 
-    private Callback getCallback() {
-        return (Callback) getActivity();
-    }
-
     public interface Callback {
         void recordStart();
 

src/main/java/de/dennisguse/opentracks/util/ActivityUtils.java

@@ -1,5 +1,7 @@
 package de.dennisguse.opentracks.util;
 
+import static android.content.Context.VIBRATOR_SERVICE;
+
 import android.app.Activity;
 import android.app.SearchManager;
 import android.content.Context;
@@ -14,6 +16,7 @@ import android.view.MenuItem;
 import android.widget.AbsListView;
 import android.widget.ListView;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.widget.SearchView;
 
 import java.util.ArrayList;
@@ -21,8 +24,6 @@ import java.util.ArrayList;
 import de.dennisguse.opentracks.ContextualActionModeCallback;
 import de.dennisguse.opentracks.R;
 
-import static android.content.Context.VIBRATOR_SERVICE;
-
 public class ActivityUtils {
 
     private static final String TAG = ActivityUtils.class.getSimpleName();
@@ -97,7 +98,7 @@ public class ActivityUtils {
         return searchView;
     }
 
-    public static void vibrate(Context context, int milliseconds) {
+    public static void vibrate(@NonNull Context context, int milliseconds) {
         final Vibrator vibrator = (Vibrator) context.getSystemService(VIBRATOR_SERVICE);
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             vibrator.vibrate(VibrationEffect.createOneShot(milliseconds, VibrationEffect.DEFAULT_AMPLITUDE));