而充气列表视图空指针异常 [英] Null Pointer Exception while inflating listview
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问题描述
我得到一个 NullPointerException异常 - 我想夸大一个的ListView 在片段。
I am getting a NullPointerException - I am trying to inflate a ListView inside a Fragment.
在例外的堆栈跟踪是
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)
类code
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
GetView method of customadapter
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;
}
在跟踪的第49行是 holder.headlineView =（TextView中）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" />
推荐答案
更改此
holder.headlineView = (TextView) convertView.findViewById(R.id.title);
到
holder.headlineView = (TextView) row.findViewById(R.id.title);
同样，对于其他视图
Similarly for other views
holder.reporterNameView = (TextView) row.findViewById(R.id.reporter);
holder.reportedDateView = (TextView) row.findViewById(R.id.date);
holder.imageView = (ImageView)row.findViewById(R.id.thumbImage);
既然你有
View row = convertView;
和
row = inflater.inflate(R.layout.listview_movies, parent, false); // layout inflated
findViewById 查找在当前膨胀的布局id的视图。所以，你需要使用View对象行初始化意见。
findViewById looks for a view with the id in the current inflated layout. So you need to use the View object row to initialize views.
OR
编辑：
黑带作为建议你也可避免
As blackbelt suggested you can also avoid
View row = convertView;
保持相同的code和只更改返回行; 到返回convertView ;
这篇关于而充气列表视图空指针异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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