fix #2317: NPE while backuping data

The previous fix for #2317 was incomplete, as the dependency of the
CentralBackupAgent onto Settings caused a NPE because Settings static
initializations require that an application has been created, which is
apparently not the case when a backup is launched by the OS.

The preference name has been isolated into a no-dependency package so
that the CentralBackupAgent does not depend on an application existing
anymore.

1 files changed, 24 insertions, 0 deletions

diff --git a/main/src/cgeo/geocaching/utils/ApplicationSettings.java b/main/src/cgeo/geocaching/utils/ApplicationSettings.java
new file mode 100644
index 0000000..99d3142
--- /dev/null
+++ b/main/src/cgeo/geocaching/utils/ApplicationSettings.java
@@ -0,0 +1,24 @@
+package cgeo.geocaching.utils;
+
+/**
+ * This utility class contains static settings that do not require a context or
+ * an application. It may not depend or use any other package from c:geo.
+ * <br/>
+ * It is used, for example, to get some settings for the BackupAgent. In this case,
+ * no application is instantiated by the OS.
+ */
+
+public class ApplicationSettings {
+
+    /**
+     * Get the name of the preferences file.
+     *
+     * @return the name of the shared preferences file without the extension
+     */
+    public static String getPreferencesName() {
+        // There is currently no Android API to get the file name of the shared preferences. Let's hardcode
+        // it without needing a cgeoapplication instance.
+        return "cgeo.geocaching_preferences";
+    }
+
+}