[英]NullPointException in ListView when getting button
我有一個奇怪的問題,似乎找不到導致它的原因。 我的ArrayAdapter中的每個視圖組件都位於getView方法中,但我的按鈕除外,這會導致NullPointerException。
適配器:
public class ItemAdapter extends ArrayAdapter<Item>{
private Context context;
private int resource;
private List<Item> list;
public ItemAdapter(Context context, int resource, List<Item> list)
{
super(context, resource, list);
this.context = context;
this.resource = resource;
this.list = list;
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
if (convertView == null)
convertView = LayoutInflater.from(context).inflate(resource, parent,false);
TextView name = (TextView) convertView.findViewById(R.id.itemName);
ImageView itemImg = (ImageView) convertView.findViewById(R.id.itemImg);
Button addToCart = (Button) convertView.findViewById(R.id.button1);
final Item item = list.get(position);
name.setText(item.getName());
UrlImageViewHelper.setUrlDrawable(itemImg, item.getPicture());
addToCart.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View view)
{
Toast.makeText(context, "Clicked", Toast.LENGTH_LONG).show();
}
});
return convertView;
}
}
具有listview的片段
@InjectView(R.id.itemList) private ListView listView;
@Inject private ItemDao dao;
private ArrayAdapter<Item> adapter;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
return inflater.inflate(R.layout.fragment_shop, container, false);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState)
{
super.onViewCreated(view, savedInstanceState);
dao.open();
List<Item> items = dao.findAll();
dao.close();
adapter = new ItemAdapter(getActivity(),R.layout.list_product_item, items);
listView.setAdapter(adapter);
}
list_product_item
<?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="horizontal"
android:paddingBottom="5dp"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:paddingTop="5dp" >
<ImageView
android:id="@+id/itemImg"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginRight="5dp"
android:scaleType="centerCrop" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/itemName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/itemStoreName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
<Button
android:id="@+id/button1"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</LinearLayout>
現在,對convertView.findViewById(R.id.button1)的調用返回一個空實例。 是什么原因造成的,我該如何解決。
你有正確的布局名稱嗎?
adapter = new GroceryItemAdapter(getActivity(), R.layout.list_textview ,items);
與
list_product_item
(我假設這是R.layout.list_product_item的文件名)
與其使用from方法獲取布局充氣器,不如嘗試在構造函數中初始化充氣器。
mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
在getView中
convertView = mInflater.inflate(your layout, null);
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