Android Listview - 自定义适配器不显示任何内容

Question

您好 StackOverflow 社区，

我遇到了一个问题（可能是愚蠢的问题），我无法弄清楚我的 ListView 出了什么问题。我有一个自定义适配器，我可以将数据传递给它，但它没有显示任何内容。这是我的代码：

LayoutInflater mInflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        View view = mInflater.inflate(R.layout.nutrition_main, null);
        listview = (ListView) view.findViewById(R.id.listView);
        // Pass the results into an ArrayAdapter
        ArrayAdapter adapter = new ArrayAdapter<>(getActivity(),
                R.layout.listviewtextview);

        for (ParseObject calories : ob) {
            Log.i("Calories", calories.get("Calories").toString());
            adapter.add(calories.get("Calories") + "");
        }

        ArrayList<String> kapow = new ArrayList<String>();
        for(int i = 0; i < adapter.getCount(); i++){
            String str = (String)adapter.getItem(i);
            kapow.add(str);
            Log.i("str", str);
        }
        SomeAdapter eh = new SomeAdapter(getActivity(), kapow);
        listview.setAdapter(eh);
        eh.notifyDataSetChanged();

这是我的 SomeAdapter 类代码：

public class SomeAdapter extends ArrayAdapter<String> {

private Context mContext;
private ArrayList<String> mItem;

public SomeAdapter(Context context, ArrayList<String> itemsArrayList) {
    super(context, R.layout.listviewtextview, itemsArrayList);
    this.mContext = context;
    this.mItem = itemsArrayList;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View v = inflater.inflate(R.layout.listviewtextview, parent, false);
    TextView mFoodName = (TextView) v.findViewById(R.id.food_name);v.findViewById(R.id.food_description);
    mFoodName.setText(mItem.get(position) + "");
    return v;
}
}

最后但同样重要的是，这是我的 listviewtextview.xml 文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:background="@drawable/row_activated"
android:layout_height="88dp">

<LinearLayout
    android:layout_height="88dp"
    android:layout_width="match_parent"
    android:layout_marginLeft="16dp"
    android:gravity="center_vertical"
    android:orientation="vertical">

    <TextView
        android:id="@+id/food_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:maxLines="1"
        android:textColor="@color/text_color"
        android:textSize="16sp"/>

    <TextView
        android:id="@+id/food_brand"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/food_name"
        android:singleLine="true"
        android:textColor="@color/text_color"
        android:textSize="14sp"/>

    <TextView
        android:id="@+id/food_description"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingRight="16dp"
        android:layout_below="@+id/label"
        android:singleLine="true"
        android:textColor="@color/text_color"
        android:textSize="12sp"/>
</LinearLayout>

Answer 1

您似乎对自定义列表视图及其适配器有某种误解，因为您将列表视图的适配器设置为eh，您甚至不需要该数组适配器，您不仅创建了数组适配器但是把数据往里面推，然后你从数组适配器里把数据一一拿到，放到kapow里面？你需要做的就是用数据和listview.setadapter(eh)初始化你的适配器eh

 View view = mInflater.inflate(R.layout.nutrition_main, null);
    listview = (ListView) view.findViewById(R.id.listView);

    // YOU DONT NEED THIS ADAPTER !
    // Pass the results into an ArrayAdapter
    // ArrayAdapter adapter = new ArrayAdapter<>(getActivity(),
    //        R.layout.listviewtextview);

    // just pass your calories string to the kapow list.                
    ArrayList<String> kapow = new ArrayList<String>();
    for (ParseObject calories : ob) {
        Log.i("Calories", calories.get("Calories").toString());
        kapow.add(calories.get("Calories") + "");
    }

    // You dont need this either
    /*for(int i = 0; i < adapter.getCount(); i++){
        String str = (String)adapter.getItem(i);
        kapow.add(str);
        Log.i("str", str);
    }*/

    SomeAdapter eh = new SomeAdapter(getActivity(), kapow);
    listview.setAdapter(eh);
    eh.notifyDataSetChanged();

编辑

您的带有视图的适配器

public class SomeAdapter extends ArrayAdapter<String> {

    private Context mContext;
    private ArrayList<String> mItem;

    public SomeAdapter(Context context, ArrayList<String> itemsArrayList) {
        super(context, R.layout.listviewtextview, itemsArrayList);
        this.mContext = context;
        this.mItem = itemsArrayList;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;
        if(convertView == null) {
            LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            convertView = inflater.inflate(R.layout.listviewtextview, parent, false);
            ViewHolder viewHolder = new ViewHolder();
            viewHolder.textView = (TextView) v.findViewById(R.id.food_name);v.findViewById(R.id.food_description);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convert.getTag();
        }
        viewHolder.textView.setText(mItem.get(position) + "");
        return convertView;
    }

    private static class ViewHolder {
        TextView textView;
    }
}

Answer 2

public class AFrag extends Fragment{
    private View view = null;
    public static final String TAG = "A";
    ListView listview;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        if (view == null) {
            view = inflater.inflate(R.layout.afrag, container, false);
            listview = (ListView) view.findViewById(R.id.listView);
            //Create your arraylist here no need to get it from adapter
            // For testing & sample here i took characters loop.
            ArrayList<String> kapow = new ArrayList<String>();
            for (char y = 'a'; y <= 'z'; y++) {
                kapow.add(String.valueOf(y));
            }
//            for (ParseObject calories : ob) {
//                Log.i("Calories", calories.get("Calories").toString());
//                ///Fill arraylist direct from the parseobject.
//                //no need to add to adapter & from adapter to arraylist
//                kapow.add(calories.get("Calories") + "");
//            }

            SomeAdapter eh = new SomeAdapter(getActivity(), kapow);
            listview.setAdapter(eh);
//            no need to call notifyDataSetChanged if you your data not changed after setting adapter
//            eh.notifyDataSetChanged();
        }
        return view;
    }

    public class SomeAdapter extends ArrayAdapter<String> {

        private Context mContext;
        private ArrayList<String> mItem;

        public SomeAdapter(Context context, ArrayList<String> itemsArrayList) {
            super(context, R.layout.listviewtextview, itemsArrayList);
            this.mContext = context;
            this.mItem = itemsArrayList;
        }

        public class ViewHolder {
            public TextView txtFoodName;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder v = null;
            if (convertView == null) {
                convertView = LayoutInflater.from(mContext).inflate(R.layout.listviewtextview, parent, false);
                v = new ViewHolder();
                v.txtFoodName = (TextView) convertView.findViewById(R.id.food_name);
                convertView.setTag(v);
            } else {
                v = (ViewHolder) convertView.getTag();
            }
            v.txtFoodName.setText(mItem.get(position) + "");
            return convertView;
        }
    }
}

ListView 项目布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"

    android:layout_height="88dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="88dp"
        android:layout_marginLeft="16dp"
        android:gravity="center_vertical"
        android:orientation="vertical">

        <TextView
            android:id="@+id/food_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:maxLines="1"
            android:textColor="#FF0000"
            android:textSize="16sp" />

        <TextView
            android:id="@+id/food_brand"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/food_name"
            android:singleLine="true"
            android:textColor="#FF0000"
            android:textSize="14sp" />

        <TextView
            android:id="@+id/food_description"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@+id/label"
            android:paddingRight="16dp"
            android:singleLine="true"
            android:textColor="#FF0000"
            android:textSize="12sp" />
    </LinearLayout>
</RelativeLayout>

片段主布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView android:id="@+id/txtCurrent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="A" />

    <Button
        android:id="@+id/btnClick"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="onBtnClick"
        android:text="Go to B" />
    <ListView android:id="@+id/listView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"></ListView>
</LinearLayout>

如果您使用的 Fragment 比上面的要多，我已经发布了代码并给出了相同的评论

建议请查看ViewHolder listview 模式

您还可以查看以下与 Listview 相关的答案 https://stackoverflow.com/a/28105884/1140237

https://stackoverflow.com/a/28104066/1140237