我收到了NullPointerException - 我正试图在ListView内对Fragment进行充气。
Exception的堆栈跟踪是
03-16 22:46:41.721: W/dalvikvm(1571): threadid=1: thread exiting with uncaught exception (group=0x400207d8)
03-16 22:46:41.840: E/AndroidRuntime(1571): FATAL EXCEPTION: main
03-16 22:46:41.840: E/AndroidRuntime(1571): java.lang.NullPointerException
03-16 22:46:41.840: E/AndroidRuntime(1571): at net.justanotherblog.swipeview.CustomListAdapter.getView(CustomListAdapter.java:49)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.AbsListView.obtainView(AbsListView.java:1315)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.ListView.makeAndAddView(ListView.java:1727)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.ListView.fillDown(ListView.java:652)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.ListView.fillFromTop(ListView.java:709)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.ListView.layoutChildren(ListView.java:1580)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.AbsListView.onLayout(AbsListView.java:1147)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.View.layout(View.java:7035)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1249)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1125)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.LinearLayout.onLayout(LinearLayout.java:1042)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.View.layout(View.java:7035)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.View.layout(View.java:7035)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1528)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.View.layout(View.java:7035)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.View.layout(View.java:7035)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1249)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1125)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.LinearLayout.onLayout(LinearLayout.java:1042)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.View.layout(View.java:7035)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.View.layout(View.java:7035)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.ViewRoot.performTraversals(ViewRoot.java:1045)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.view.ViewRoot.handleMessage(ViewRoot.java:1727)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.os.Handler.dispatchMessage(Handler.java:99)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.os.Looper.loop(Looper.java:123)
03-16 22:46:41.840: E/AndroidRuntime(1571): at android.app.ActivityThread.main(ActivityThread.java:4627)
03-16 22:46:41.840: E/AndroidRuntime(1571): at java.lang.reflect.Method.invokeNative(Native Method)
03-16 22:46:41.840: E/AndroidRuntime(1571): at java.lang.reflect.Method.invoke(Method.java:521)
03-16 22:46:41.840: E/AndroidRuntime(1571): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:876)
03-16 22:46:41.840: E/AndroidRuntime(1571): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)
03-16 22:46:41.840: E/AndroidRuntime(1571): at dalvik.system.NativeStart.main(Native Method)
班级代码
public static class Songs_Fragment extends Fragment {
public Songs_Fragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.songs_fragment, container, false);
ListView lv1 = (ListView) rootView.findViewById(R.id.songs_list);
ArrayList<NewsItem> image_details = getListData();
CustomListAdapter C_Adapter = new CustomListAdapter(getActivity(),image_details);
lv1.setAdapter(C_Adapter);
return rootView;
}
customadapter的GetView方法
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
View row = convertView;
if (row == null) {
LayoutInflater inflater = LayoutInflater.from(this.context);
row = inflater.inflate(R.layout.listview_movies, parent, false);
holder = new ViewHolder();
holder.headlineView = (TextView) convertView.findViewById(R.id.title);
holder.reporterNameView = (TextView) convertView.findViewById(R.id.reporter);
holder.reportedDateView = (TextView) convertView.findViewById(R.id.date);
holder.imageView = (ImageView) convertView.findViewById(R.id.thumbImage);
row.setTag(holder);
} else {
holder = (ViewHolder) row.getTag();
}
NewsItem newsItem = (NewsItem) listData.get(position);
holder.headlineView.setText(newsItem.getHeadline());
holder.reporterNameView.setText("By, " + newsItem.getReporterName());
holder.reportedDateView.setText(newsItem.getDate());
if (holder.imageView != null) {
new ImageDownloaderTask(holder.imageView).execute(newsItem.getUrl());
}
return row;
}
static class ViewHolder {
TextView headlineView;
TextView reporterNameView;
TextView reportedDateView;
ImageView imageView;
}
追踪中的第49行是holder.headlineView = (TextView) convertView.findViewById(R.id.title);
最后这里是listview_movies.xml
<?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="wrap_content"
android:minHeight="50dp"
android:orientation="horizontal" >
<ImageView
android:id="@+id/thumbImage"
android:layout_width="70dp"
android:layout_height="70dp"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:background="@drawable/list_placeholder" />
<TextView
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@id/thumbImage"
android:paddingLeft="5dp"
android:paddingTop="5dp"
android:text=""
android:textColor="@drawable/list_item_text_selector"
android:textStyle="bold"
android:typeface="sans" />
<TextView
android:id="@+id/reporter"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/title"
android:layout_marginTop="5dip"
android:layout_toRightOf="@id/thumbImage"
android:paddingLeft="5dp"
android:text=""
android:textColor="@drawable/list_item_text_selector"
android:textSize="12sp" />
<TextView
android:id="@+id/date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/reporter"
android:layout_alignBottom="@+id/reporter"
android:layout_alignParentRight="true"
android:paddingRight="5dp"
android:text=""
android:textColor="@drawable/list_item_text_selector"
android:textSize="12sp" />
答案 0 :(得分：3)
更改此
holder.headlineView = (TextView) convertView.findViewById(R.id.title);
到
holder.headlineView = (TextView) row.findViewById(R.id.title);
同样适用于其他观点
holder.reporterNameView = (TextView) row.findViewById(R.id.reporter);
holder.reportedDateView = (TextView) row.findViewById(R.id.date);
holder.imageView = (ImageView)row.findViewById(R.id.thumbImage);
因为你有
View row = convertView;
和
row = inflater.inflate(R.layout.listview_movies, parent, false); // layout inflated
findViewById在当前膨胀的布局中查找id为id的视图。因此，您需要使用View对象row来初始化视图。
OR
编辑：
黑带建议你也可以避免
View row = convertView;
保留相同的代码，仅将return row;更改为return convertView;