Question

我有一个选项卡布局包含一个列表视图，该列表视图在每次选择一个选项卡时都会更新但是新项目将添加到列表中，并且在添加新项目之前不会清除列表

public class DemoObjectFragment extends Fragment {
ListView lv;
private String TAG = DemoObjectFragment.class.getSimpleName();
public static ArrayList<HashMap<String, String>> contList = new ArrayList<>();
android.widget.ListAdapter adapter;

@Override
public View onCreateView(LayoutInflater inflater,
                         ViewGroup container, Bundle savedInstanceState) {
    View vw = inflater.inflate(R.layout.coin, container, false);
    try {
        for (int i = 0; i < contactList.size(); i++) {
            Log.v(TAG, "Response: " + contactList.get(i));
            if (Integer.valueOf(contactList.get(i).get("asset_id")) == MainActivity.typeCurrency) {
                contList.add(contactList.get(i));
            }
        }
    }catch (Exception e){
        e.getMessage();
    }


    lv=vw.findViewById(R.id.exchangeList);
    lv.setAdapter(null);
    adapter = new SimpleAdapter(getActivity(), contList, R.layout.list_item, new String[]{"sourceName", "priceCurrency"},
            new int[]{R.id.sourceName, R.id.priceCurrency});
    lv.setAdapter(adapter);
    contactList=new ArrayList<>();
    return vw;
}

}

Answer 1

您需要清除项目，然后将新项目添加到列表中，

 contList.clear();

尝试添加clear（）方法。

 try {
    contList.clear();
    for (int i = 0; i < contactList.size(); i++) {
        Log.v(TAG, "Response: " + contactList.get(i));
        if (Integer.valueOf(contactList.get(i).get("asset_id")) == MainActivity.typeCurrency) {
            contList.add(contactList.get(i));
        }
    }
}catch (Exception e){
    e.getMessage();
}

Answer 2

public class DemoObjectFragment extends Fragment {
ListView lv;
private String TAG = DemoObjectFragment.class.getSimpleName();
public static ArrayList<HashMap<String, String>> contList;
android.widget.ListAdapter adapter;

@Override
public View onCreateView(LayoutInflater inflater,
                     ViewGroup container, Bundle savedInstanceState) {
View vw = inflater.inflate(R.layout.coin, container, false);
try {
    contList = new ArrayList<>();
    for (int i = 0; i < contactList.size(); i++) {
        Log.v(TAG, "Response: " + contactList.get(i));
        if (Integer.valueOf(contactList.get(i).get("asset_id")) == MainActivity.typeCurrency) {
            contList.add(contactList.get(i));
        }
    }
}catch (Exception e){
    e.getMessage();
}


lv=vw.findViewById(R.id.exchangeList);
lv.setAdapter(null);
adapter = new SimpleAdapter(getActivity(), contList, R.layout.list_item, new String[]{"sourceName", "priceCurrency"},
        new int[]{R.id.sourceName, R.id.priceCurrency});
lv.setAdapter(adapter);
contactList=new ArrayList<>();
return vw;
   }
}

那会很好;）

listview.setAdapter（null）似乎不起作用

2 个答案: