android 项目问题 求大神指导一下 ?报错

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences com.edu.buu.oplayer.OPlayerApplication.getSharedPreferences(java.lang.String, int)' on a null object reference

public class OPreference {
private static final String PREFERENCE_NAME = "preference.db";
private SharedPreferences mPreference;
public OPreference() {
mPreference = OPlayerApplication.getApplication().
getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE); //这句话报错
}
public class OPlayerApplication extends Application {


private static OPlayerApplication mApplication;


/** OPlayer SD卡缓存路 */
public static final String OPLAYER_CACHE_BASE = Environment.getExternalStorageDirectory() + "/oplayer";
/** 视频截图缓冲路径 */
public static final String OPLAYER_VIDEO_THUMB = OPLAYER_CACHE_BASE + "/thumb/";
/** 首次扫描 */
public static final String PREF_KEY_FIRST = "application_first";


@Override
public void onCreate() {
super.onCreate();
mApplication = this;
init();
}


private void init() {
//创建缓存目录
FileUtils.createIfNoExists(OPLAYER_CACHE_BASE);
FileUtils.createIfNoExists(OPLAYER_VIDEO_THUMB);
}


public static OPlayerApplication getApplication() {
return mApplication;
}


public void destory() {
mApplication = null;
}
}