Question

我是Android开发的新手。我面临的问题是我想从停止名称获取stop_id。我有一个数据库，它包含所有必需的数据。当我直接在数据库中运行查询，所以它给了我正确的答案，但它在android中不起作用。如果我使用getString（0）函数，它会给我null 如果使用getInt（0）函数给我0，请帮帮我..

这是我的代码：

public class Bus_Schedule_tab3 extends Fragment {

DataBase_Class db;
Button btn_go;
EditText source_txt;
EditText destination_txt;
int source_id ;
int destination_id ;
String Source_Destination_querry;

String sourceTxt , destinationTxt;

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.bus_schedule_tab3, container, false);

    btn_go = (Button) rootView.findViewById(R.id.btn_go);
    db = new DataBase_Class(getActivity());
    source_txt = (EditText) rootView.findViewById(R.id.edtxt_source);
    destination_txt = (EditText) rootView.findViewById(R.id.edtxt_destination);

    getOnlySource();
    return rootView;
}

public void getOnlySource() {
    btn_go.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            StringBuffer buffer = new StringBuffer();
            Cursor c_sourse_id = db.GetOnlySource("select stop_id from stops_table where stop_name  = '"+source_txt.getText().toString()+"'");
            Cursor  c_destination_id = db.GetOnlySource("select stop_id from stops_table where stop_name  = '"+destination_txt.getText().toString()+"'");

            while (c_sourse_id.moveToNext()) {
                source_id =  c_sourse_id.getInt(0);}
            while (c_destination_id.moveToNext()) {
                destination_id = c_destination_id.getInt(0);}



            buffer.append(source_id +"  "+ destination_id);

             showMessage("Data",buffer.toString());
          }
       });
       }

public void showMessage(String title,String Message){
    AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
    builder.setCancelable(true);
    builder.setTitle(title);
    builder.setMessage(Message);
    builder.show();
   }
}

Answer 1

使用它：

cursor.getInt(cursor.getColumnIndex(USER_ID))

其中USER_ID是列的名称

Answer 2

检查你的db对象是否为null，因为你没有将非null对象作为getOnlySource（）方法中的参数传递。

Android中sqlite数据库的数据检索问题

2 个答案: