Question

数据库名称：＆＃34;事件＆＃34;。我想添加属于＆＃34; name＆＃34;，＆＃34; status＆＃34;，＆＃34; number＆＃34;的所有行的数据。表事件的属性分别为不同的列表tmp1，tmp2，tmp3。我有以下代码

public class OneFragment extends Fragment {

FrameLayout frame;
RecyclerView recList;
TextView BlankDB;
private SQLiteDatabase datab;
public ArrayList<String> array = new ArrayList<String>();


public OneFragment() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View v = inflater.inflate(R.layout.fragment_one, container, false);
    frame = (FrameLayout)v.findViewById(R.id.frame);

    if(checkDataBase()) {
        recList = new RecyclerView(getActivity());
        recList.setHasFixedSize(true);
        LinearLayoutManager llm = new LinearLayoutManager(getContext());
        llm.setOrientation(LinearLayoutManager.VERTICAL);
        recList.setLayoutManager(llm);

        //Getting the elements from DB
        ArrayList<String> tmp1 = getListofevents("events", "name");
        ArrayList<String> tmp2 = getListofstatus("events","status");
        ArrayList<String> tmp3 = getListofmembers("events", "numbers");
        for(int i=0;i<tmp3.size();i++){
            Log.e("The length of tmp1 is: ", String.valueOf(tmp1.get(i)));
            Log.e("The length of tmp2 is: ", String.valueOf(tmp2.get(i)));
            Log.e("The length of tmp3 is: ", String.valueOf(tmp3.get(i)));


        }

      //  String[] array4 = tmp4.toArray(new String[tmp4.size()]);
        Log.e("The length of tmp1 is: ", String.valueOf(tmp1.size()));

        ContactAdapter ca = new ContactAdapter(tmp1);
        recList.setAdapter(ca);
        frame.addView(recList);
    }

    else{
        BlankDB = new TextView(getActivity());
        BlankDB.setText("There is no event to display");
        BlankDB.setTextSize(40);
        frame.addView(BlankDB);
    }
    return v;
}

private boolean checkDataBase() {
    SQLiteDatabase checkDB = null;
    try {
        checkDB = SQLiteDatabase.openDatabase(getActivity().getDatabasePath("events").toString(), null,
                SQLiteDatabase.OPEN_READONLY);
        checkDB.close();
    } catch (SQLiteException e) {
        // database doesn't exist yet.
    }
    return checkDB != null;
}


public ArrayList<String> getListofevents(String evName,String attribute) {

    datab = getActivity().openOrCreateDatabase(evName, Context.MODE_PRIVATE, null);

    Cursor crs = datab.rawQuery("SELECT * FROM event", null);

    while(crs.moveToNext()){
        String uname = crs.getString(crs.getColumnIndex(attribute));
        Log.e("The string is : ", uname);
        array.add(uname);
    }
    crs.close();
    datab.close();
    return array;
}

public ArrayList<String> getListofstatus(String evName,String attribute) {

    datab = getActivity().openOrCreateDatabase(evName, Context.MODE_PRIVATE, null);

    Cursor crs = datab.rawQuery("SELECT * FROM event", null);

    while(crs.moveToNext()){
        String uname = crs.getString(crs.getColumnIndex(attribute));
        Log.e("The string is : ", uname);
        array.add(uname);
    }
    crs.close();
    datab.close();
    return array;
}

public ArrayList<String> getListofmembers(String evName,String attribute) {

    datab = getActivity().openOrCreateDatabase(evName, Context.MODE_PRIVATE, null);

    Cursor crs = datab.rawQuery("SELECT * FROM event", null);

    while(crs.moveToNext()){
        String uname = crs.getString(crs.getColumnIndex(attribute));
        Log.e("The string is : ", uname);
        array.add(uname);
    }
    crs.close();
    datab.close();
    return array;
}

}

但问题是所有列表都获取了所有查询选择的所有数据。表事件具有以下数据

＆＃34;名称＆＃34; ：晚餐，abcd

＆＃34;状态＆＃34; ：是的，是的

＆＃34;数＆＃34; ：1,1

但是编译结果生成的日志显示

04-06 23:33:59.023 2302-2302/? E/The string is :: dinner
04-06 23:33:59.023 2302-2302/? E/The string is :: abcd
04-06 23:33:59.024 2302-2302/? E/The string is :: Yes
04-06 23:33:59.024 2302-2302/? E/The string is :: Yes
04-06 23:33:59.024 2302-2302/? E/The string is :: 1
04-06 23:33:59.024 2302-2302/? E/The string is :: 1
04-06 23:33:59.029 2302-2302/? E/The length of tmp1 is:: dinner
04-06 23:33:59.029 2302-2302/? E/The length of tmp2 is:: dinner
04-06 23:33:59.029 2302-2302/? E/The length of tmp3 is:: dinner
04-06 23:33:59.029 2302-2302/? E/The length of tmp1 is:: abcd
04-06 23:33:59.029 2302-2302/? E/The length of tmp2 is:: abcd
04-06 23:33:59.029 2302-2302/? E/The length of tmp3 is:: abcd
04-06 23:33:59.029 2302-2302/? E/The length of tmp1 is:: Yes
04-06 23:33:59.029 2302-2302/? E/The length of tmp2 is:: Yes
04-06 23:33:59.029 2302-2302/? E/The length of tmp3 is:: Yes
04-06 23:33:59.029 2302-2302/? E/The length of tmp1 is:: Yes
04-06 23:33:59.029 2302-2302/? E/The length of tmp2 is:: Yes
04-06 23:33:59.029 2302-2302/? E/The length of tmp3 is:: Yes
04-06 23:33:59.029 2302-2302/? E/The length of tmp1 is:: 1
04-06 23:33:59.029 2302-2302/? E/The length of tmp2 is:: 1
04-06 23:33:59.029 2302-2302/? E/The length of tmp3 is:: 1
04-06 23:33:59.029 2302-2302/? E/The length of tmp1 is:: 1
04-06 23:33:59.029 2302-2302/? E/The length of tmp2 is:: 1
04-06 23:33:59.029 2302-2302/? E/The length of tmp3 is:: 1
04-06 23:33:59.029 2302-2302/? E/The length of tmp1 is:: 6

我是android新手。任何帮助将不胜感激。

Answer 1

您正在使用相同的实例'array'来处理所有选择。这会导致“临时实例”（1,2,3）保存数组所具有的所有数据，因为它们使用相同的引用。

示例：

public ArrayList<String> getListofevents(String evName,String attribute) {

    ArrayList<String> arrAux = new ArrayList<String>();

    datab = getActivity().openOrCreateDatabase(evName, Context.MODE_PRIVATE, null);

    Cursor crs = datab.rawQuery("SELECT * FROM event", null);

    while(crs.moveToNext()){
                String uname = crs.getString(crs.getColumnIndex(attribute));
          Log.e("The string is : ", uname);
          arrAux.add(uname);
     }
     crs.close();
     datab.close();


    return arrAux;
}

错误。数据库查询同时添加到多个列表

1 个答案: