[英]android textView.setText() gives me null pointer exception
我创建了一个自定义适配器,将图像放在listView中,但是在textView.setText(text)中给了我一个空指针异常。
这是我的适配器异常时的部分:
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(rowResourceId, parent, false);
ImageView imageView = (ImageView) rowView.findViewById(R.id.imageFileView);
TextView textView = (TextView) rowView.findViewById(R.id.fileName);
int pos = position+4;
String name = Names[pos];
String extFile = Names[pos].substring(Names[pos].lastIndexOf(".")+1);
String uri = "drawable/"+extFile+".png";
textView.setText(name);
Uri imgUri=Uri.parse(uri);
imageView.setImageURI(imgUri);
return rowView;
}
这是我有异常的时候我的LogCat:
06-14 12:15:04.616: E/AndroidRuntime(678): FATAL EXCEPTION: main
06-14 12:15:04.616: E/AndroidRuntime(678): java.lang.NullPointerException
06-14 12:15:04.616: E/AndroidRuntime(678): at com.example.poc_cubbyhole.ItemAdapter.getView(ItemAdapter.java:59)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:220)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.AbsListView.obtainView(AbsListView.java:1430)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.ListView.makeAndAddView(ListView.java:1745)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.ListView.fillSpecific(ListView.java:1290)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.ListView.layoutChildren(ListView.java:1588)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.AbsListView.onLayout(AbsListView.java:1260)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.view.View.layout(View.java:7175)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.RelativeLayout.onLayout(RelativeLayout.java:912)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.view.View.layout(View.java:7175)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.view.View.layout(View.java:7175)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1254)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1130)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.LinearLayout.onLayout(LinearLayout.java:1047)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.view.View.layout(View.java:7175)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.widget.FrameLayout.onLayout(FrameLayout.java:338)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.view.View.layout(View.java:7175)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.view.ViewRoot.performTraversals(ViewRoot.java:1140)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.os.Handler.dispatchMessage(Handler.java:99)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.os.Looper.loop(Looper.java:123)
06-14 12:15:04.616: E/AndroidRuntime(678): at android.app.ActivityThread.main(ActivityThread.java:3683)
06-14 12:15:04.616: E/AndroidRuntime(678): at java.lang.reflect.Method.invokeNative(Native Method)
06-14 12:15:04.616: E/AndroidRuntime(678): at java.lang.reflect.Method.invoke(Method.java:507)
06-14 12:15:04.616: E/AndroidRuntime(678): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
06-14 12:15:04.616: E/AndroidRuntime(678): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
06-14 12:15:04.616: E/AndroidRuntime(678): at dalvik.system.NativeStart.main(Native Method)
这是在我的listView中创建项目的xml文件:
<ImageView
android:id="@+id/imageFileView"
android:layout_width="32dp"
android:layout_height="32dp"
android:layout_alignParentLeft="true"
android:layout_marginLeft="9dp"
android:layout_alignParentTop="true"/>
<TextView
android:layout_alignBottom="@+id/fileName"
android:layout_width="97dp"
android:layout_height="32dp"
android:id="@+id/textView"
android:layout_alignParentLeft="true"
android:layout_marginLeft="66dp"
android:layout_alignParentRight="true"
android:gravity="center_vertical"/>
这是我的listView:
<com.example.poc_cubbyhole.widgets.PullToRefreshListView
android:id="@+id/list_files"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_above="@+id/button_upload"
android:layout_alignParentTop="true"
/>
我使用一个小部件来更改添加拉并刷新到我的listView
改变这个
TextView textView = (TextView) rowView.findViewById(R.id.fileName);
至
TextView textView = (TextView) rowView.findViewById(R.id.textView);
在您的getView
方法中,因为您的TextView
ID是textView
而不是fileName
您可能会从此处的数组位置获取空值:
int pos = position+4;
String name = Names[pos];
对于中间解决方案,您可以添加以下内容:
int pos = position+4;
String name = ""+Names[pos];
所以你没有空值,也没有空指针。
现在,如果您想要获取nul值的正确解决方案,则调试应用程序,并在每次执行时检查数组和名称的值 。 祝好运..
即使我的View ID是正确的,我也面临着一个问题。 但是最后我更改了id并清理了项目,然后构建了一次。 它工作正常。
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