Baffling recursive ClassCastExceptions when reading Android default shared preferences

Seems like I must be doing something basic very wrong, but the results are strange, and I'm having trouble tracking the problem down.

This is in my my Activity's onCreate()

PreferenceManager.setDefaultValues(this, R.xml.metronome_preferences, false);
mSharedPrefs=PreferenceManager.getDefaultSharedPreferences(this);

The following code lives in onStart().

Map<String,?> map = mSharedPrefs.getAll();
boolean t = mSharedPrefs.contains("tempo_list_pref");
Log.d(logID, "t= " +开发者_C百科 t + " preferences=" + map.toString());
mBPMOption = mSharedPrefs.getLong("tempo_list_pref", 100);

Log cat correctly shows:

02-05 11:14:27.605: DEBUG/Metronome(16147): t=true preferences={graphics_list_pref=1, conduct_list_pref=12.0f, tempo_list_pref=140, audio_list_pref=2, meter_list_pref=5}

mBPMOption is a long. The shared prefs object is apparently valid as I can both retrieve the preferences as a map, and test for the presence of a preferences, but the call to getLong() causes ClassCastExceptions to be recursively thrown. At least, that's how I'm interpreting what I'm seeing in the debugger. The error object e contains e.cause, e.cause.cause, ... .

I'm getting this same error in the emulator and on the Google ION dev phone.

Any thoughts on this would be appreciated.

it would help if you showed the stack trace, but...

private static final class SharedPreferencesImpl implements SharedPreferences {
    ...
    public long getLong(String key, long defValue) {
        synchronized (this) {
            Long v = (Long) mMap.get(key);
            return v != null ? v : defValue;
        }
    }

10p says your ClassCastException is being thrown there. when the documentation says getLong will throw ClassCastException isn't a Long, it really means it: an int won't do. are you sure you stored this as a long? adding this line to your code will tell you what you've got:

System.err.println(map.get("tempo_list_pref").getClass());