查询到sqlite数据库出错了

Question

i have a query that writes to the sqlitedatabase on my android device

everytime I call the query i get an nullpointerexception,

here my query:

Cursor c =  onzedatabase.query(databasetabel, allekolommen, 
                                       waar, null, null, null, null, null);

after some research i found out that onzedatabase = null although i use all the correct methods as needed (=>onzedatabase works for all the other queries on the same database)

in my opinion a solution is given in the following stackoverflow question: nullpointerexception fault

but how do i implement this solution on my android device, i don't uderstand anything of the answer

thanks for helping me in advance

edit:

here my initialazing of onzedatabase

private dbhulp onzehelper;
    private final Context onzecontext;
    private SQLiteDatabase onzedatabase;


    public static class dbhulp extends SQLiteOpenHelper
    {

        public dbhulp(Context context) {
            super(context, ADbAdapter.databasenaam, null, ADbAdapter.databaseversie);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        }



    }
    public ABezurAdapter(Context c) {
        onzecontext = c;
    }

    public ABezurAdapter open() throws SQLException{
        onzehelper = new dbhulp(onzecontext);
        onzedatabase = onzehelper.getWritableDatabase();
        return this;
    }

Answer 1

当onzedatabase为null ，很可能之前没有调用open() 。