Bugfix: TrackRecordingService must handle restarts while recording.

We now store the Track.Id in a sharedPreferences.

Functionality was removed in e09b04308c

Fixes #2333

src/main/java/de/dennisguse/opentracks/services/TrackIdStorage.java

@@ -0,0 +1,56 @@
+package de.dennisguse.opentracks.services;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import de.dennisguse.opentracks.data.models.Track;
+
+/**
+ * For handling restarts of TrackRecordingService: while recording, stores the {@link de.dennisguse.opentracks.data.models.Track.Id}.
+ */
+class TrackIdStorage {
+
+    private final static String SHARED_PREFERENCE_NAME = "TrackRecordingService_pref";
+
+    private final static String KEY = "trackId_key";
+
+    private static SharedPreferences sharedPreferences;
+
+    private static void init(Context context) {
+        if (sharedPreferences == null) {
+            sharedPreferences = context.getSharedPreferences(SHARED_PREFERENCE_NAME, Context.MODE_PRIVATE);
+        }
+    }
+
+    @Nullable
+    public static Track.Id get(Context context) {
+        TrackIdStorage.init(context);
+
+        long value = sharedPreferences.getLong(KEY, -1);
+        if (value < 0) {
+            return null;
+        }
+
+        return new Track.Id(value);
+    }
+
+    public static void set(Context context, @NonNull Track.Id trackId) {
+        TrackIdStorage.init(context);
+
+        SharedPreferences.Editor editor = sharedPreferences.edit();
+        editor.putLong(KEY, trackId.id());
+        editor.commit();
+    }
+
+    public static void unset(Context context) {
+        TrackIdStorage.init(context);
+
+        SharedPreferences.Editor editor = sharedPreferences.edit();
+        editor.remove(KEY);
+        editor.commit();
+    }
+
+}