fix #3756: NPE when changing map source

3 files changed, 12 insertions, 6 deletions

diff --git a/main/src/cgeo/geocaching/maps/CGeoMap.java b/main/src/cgeo/geocaching/maps/CGeoMap.java
index f06a42f..9f2f89e 100644
--- a/main/src/cgeo/geocaching/maps/CGeoMap.java
+++ b/main/src/cgeo/geocaching/maps/CGeoMap.java
@@ -42,6 +42,7 @@ import cgeo.geocaching.utils.Log;
 import org.apache.commons.collections4.CollectionUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.lang3.builder.HashCodeBuilder;
+import org.eclipse.jdt.annotation.NonNull;
 import rx.Scheduler;
 import rx.Subscription;
 import rx.functions.Action1;
@@ -785,15 +786,16 @@ public class CGeoMap extends AbstractMap implements OnMapDragListener, ViewFacto
     /**
      * Restart the current activity if the map provider has changed, or change the map source if needed.
      *
-     * @param mapSource
+     * @param newSource
      *            the new map source, which can be the same as the current one
      * @return true if a restart is needed, false otherwise
      */
-    private boolean changeMapSource(final MapSource mapSource) {
-        final boolean restartRequired = !MapProviderFactory.isSameActivity(MapProviderFactory.getMapSource(currentSourceId), mapSource);
+    private boolean changeMapSource(@NonNull final MapSource newSource) {
+        final MapSource oldSource = MapProviderFactory.getMapSource(currentSourceId);
+        final boolean restartRequired = oldSource == null || !MapProviderFactory.isSameActivity(oldSource, newSource);
 
-        Settings.setMapSource(mapSource);
-        currentSourceId = mapSource.getNumericalId();
+        Settings.setMapSource(newSource);
+        currentSourceId = newSource.getNumericalId();
 
         if (restartRequired) {
             mapRestart();
diff --git a/main/src/cgeo/geocaching/maps/MapProviderFactory.java b/main/src/cgeo/geocaching/maps/MapProviderFactory.java
index b928a1e..890274d 100644
--- a/main/src/cgeo/geocaching/maps/MapProviderFactory.java
+++ b/main/src/cgeo/geocaching/maps/MapProviderFactory.java
@@ -10,6 +10,8 @@ import cgeo.geocaching.settings.Settings;
 import cgeo.geocaching.utils.Log;
 
 import org.apache.commons.lang3.StringUtils;
+import org.eclipse.jdt.annotation.NonNull;
+import org.eclipse.jdt.annotation.Nullable;
 
 import android.view.Menu;
 import android.view.SubMenu;
@@ -51,7 +53,7 @@ public class MapProviderFactory {
         return mapSources;
     }
 
-    public static boolean isSameActivity(final MapSource source1, final MapSource source2) {
+    public static boolean isSameActivity(@NonNull final MapSource source1, @NonNull final MapSource source2) {
         final MapProvider provider1 = source1.getMapProvider();
         final MapProvider provider2 = source2.getMapProvider();
         return provider1 == provider2 && provider1.isSameActivity(source1, source2);
@@ -75,6 +77,7 @@ public class MapProviderFactory {
      * @param id the map source id
      * @return the map source, or <tt>null</tt> if <tt>id</tt> does not correspond to a registered map source
      */
+    @Nullable
     public static MapSource getMapSource(int id) {
         for (MapSource mapSource : mapSources) {
             if (mapSource.getNumericalId() == id) {
diff --git a/main/src/cgeo/geocaching/settings/Settings.java b/main/src/cgeo/geocaching/settings/Settings.java
index 59140ba..7a4dfdd 100644
--- a/main/src/cgeo/geocaching/settings/Settings.java
+++ b/main/src/cgeo/geocaching/settings/Settings.java
@@ -599,6 +599,7 @@ public class Settings {
         putInt(R.string.pref_lastmaplon, mapViewCenter.getLongitudeE6());
     }
 
+    @NonNull
     public static synchronized MapSource getMapSource() {
         if (mapSource != null) {
             return mapSource;