原来的DatabaseOption和DatabaseManager总是报空指针异常，是因为上下文为Application时无法通过SQLiteOpenHelper的方法getWritableDatabase获取可读写的数据库。

在menifest文件中初始化后可以解决该问题。即在application标签下添加name属性，并在name属性对应的包名下新建一个类继承Application。

public class RailSetApplication extends Application {    private static Application mInstance;    @Override    public void onCreate() {        super.onCreate();        mInstance = this;    }    public static Context getInstance()    {        if(null == mInstance){            mInstance = new RailSetApplication();        }        Log.e("RailSetApplication", "is null "+(null == mInstance));//        return mInstance.getApplicationContext();        return mInstance;    }}