每当我尝试加入这一行崩溃我的应用程序。我不能把它在正确的位置？

Whenever I try to add this line it crashes my app. Am I not putting it in the right spot?

    preferences.registerOnSharedPreferenceChangeListener(myActivity.this);

下面是我的课

class Simulation extends View {

    // I declare my program variables here
    public Simulation(Context context) {
        super(context);
        // get the preferences
        SharedPreferences preferences = PreferenceManager
                .getDefaultSharedPreferences(context);
        preferences
                .registerOnSharedPreferenceChangeListener(myActivity.this);
        String storedPreference = preferences.getString("nPref", "0");
    }

    public void onSharedPreferenceChanged(
            SharedPreferences sharedPreferences, String key) {
        Log.i(TAG, "preferences changed!");
    }
}

谢谢！

推荐答案

做这样

SharedPreferences.OnSharedPreferenceChangeListener prefListener = 
        new SharedPreferences.OnSharedPreferenceChangeListener() {
    public void onSharedPreferenceChanged(SharedPreferences prefs,
            String key) {
        if (key.equals("date")) {
        }
    }
};

和

preferences.registerOnSharedPreferenceChangeListener(prefListener);