Java 非空ListView给出无效索引0的错误,大小为0
我有一个ListView片段,我在其中注册了上下文菜单的ListView:Java 非空ListView给出无效索引0的错误,大小为0,java,android,listview,android-listview,Java,Android,Listview,Android Listview,我有一个ListView片段,我在其中注册了上下文菜单的ListView: CourseArrayAdapter adapter = new CourseArrayAdapter(getActivity(), register.getCourseListByGrade(grade)); setListAdapter(adapter); getListView().setLongClickable(true); registerForContextMenu(getListV
CourseArrayAdapter adapter = new CourseArrayAdapter(getActivity(), register.getCourseListByGrade(grade));
setListAdapter(adapter);
getListView().setLongClickable(true);
registerForContextMenu(getListView());
我确信我的适配器包含一个非空列表,因为它在ListView中填充了我的自定义视图
上下文菜单相关方法:
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
MenuInflater inflater = getActivity().getMenuInflater();
inflater.inflate(R.menu.menu_course_context, menu);
AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo)menuInfo;
menu.setHeaderTitle(((CourseArrayAdapter)getListAdapter()).getItem(info.position).getCourseName());
}
@Override
public boolean onContextItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.action_remove:
register.removeCourse(((CourseArrayAdapter) getListAdapter()).getItem(((AdapterView.AdapterContextMenuInfo) item.getMenuInfo()).position).getId());
return true;
case R.id.action_edit:
register.editCourse(((CourseArrayAdapter) getListAdapter()).getItem(((AdapterView.AdapterContextMenuInfo) item.getMenuInfo()).position).getId());
return true;
}
return super.onContextItemSelected(item);
}
在onCreatedContextMenu
中调用getListAdapter().getItem(info.position)
不会出错,并显示正确的菜单标题。但是,单击选项后,将显示以下错误:
08-14 16:02:46.964 1923-1923/com.andhruv.schoolapp E/MessageQueue JNI﹕ java.lang.IndexOutOfBoundsException:索引0无效,大小为0
位于java.util.ArrayList.ThrowindexOutfBoundsException(ArrayList.java:255)
获取(ArrayList.java:308)
位于android.widget.ArrayAdapter.getItem(ArrayAdapter.java:337)
在com.andhruv.schoolapp.CourseListFragment.onContextItemSelected上(CourseListFragment.java:62)
在android.support.v4.app.Fragment.performContextItemSelected(Fragment.java:1912)
java:62是行
register.editCourse(((CourseArrayAdapter) getListAdapter()).getItem(((AdapterView.AdapterContextMenuInfo) item.getMenuInfo()).position).getId());
课程简介:
class CourseArrayAdapter extends ArrayAdapter<Course> {
private Gpa gpaCalculator;
public CourseArrayAdapter(Context context, List<Course> values) {
super(context, 0,values);
gpaCalculator = new Gpa();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.item_course,parent,false);
TextView textViewCourseName = (TextView)rowView.findViewById(R.id.textViewCourseName);
TextView textViewGpa = (TextView)rowView.findViewById(R.id.textViewGpa);
TextView textViewGrade = (TextView)rowView.findViewById(R.id.textViewGrade);
TextView textViewType = (TextView)rowView.findViewById(R.id.textViewType);
TextView textViewCategory = (TextView)rowView.findViewById(R.id.textViewCategory);
textViewCourseName.setText(getItem(position).getCourseName());
textViewGpa.setText(String.valueOf(gpaCalculator.calcCourseVal(getItem(position).getLetterGrade(),getItem(position).getCourseLevel(),true)));
textViewType.setText(String.valueOf(getItem(position).getCourseLevel()));
textViewCategory.setText(String.valueOf(getItem(position).getCategory()).replace('_',' '));
textViewGrade.setText(String.valueOf(getItem(position).getLetterGrade()));
textViewCourseName.setTag(getItem(position).getId());
return rowView;
}
class CourserLayaAdapter扩展了ArrayAdapter{
私人Gpa计算程序;
公共课程arrayadapter(上下文、列表值){
super(上下文,0,值);
gpaCalculator=新的Gpa();
}
@凌驾
公共视图getView(int位置、视图转换视图、视图组父视图){
LayoutInflater充气器=(LayoutInflater)getContext().getSystemService(Context.LAYOUT\u充气器\u SERVICE);
视图行视图=充气机。充气(右布局。项目\路线,父项,false);
TextView textViewCourseName=(TextView)rowView.findViewById(R.id.textViewCourseName);
TextView textViewGpa=(TextView)rowView.findViewById(R.id.textViewGpa);
TextView textViewGrade=(TextView)rowView.findViewById(R.id.textViewGrade);
TextView textViewType=(TextView)rowView.findViewById(R.id.textViewType);
TextView textViewCategory=(TextView)rowView.findViewById(R.id.textViewCategory);
textViewCourseName.setText(getItem(position.getCourseName());
textViewGpa.setText(String.valueOf(gpacalCalculator.calcCourseVal(getItem(position).getLetterGrade(),getItem(position).getCourseLevel(),true));
textViewType.setText(String.valueOf(getItem(position).getCourseLevel());
textViewCategory.setText(String.valueOf(getItem(position).getCategory()).replace(“”,“”));
textViewGrade.setText(String.valueOf(getItem(position).getLetterGrade());
textViewCourseName.setTag(getItem(position.getId());
返回行视图;
}
}
为什么调用
((CourseArrayAdapter)getListAdapter()).getItem(info.position)
在onCreateContextMenu中工作,但在onContextItemSelected中不工作?我怀疑您在以下代码中没有正确修改适配器:
register.removeCourse(((CourseArrayAdapter) getListAdapter()).getItem(((AdapterView.AdapterContextMenuInfo) item.getMenuInfo()).position).getId());
或
对于我来说,很难提出一个完整的代码修复方案,因为您的代码不适合我的编码风格,当然我也不太了解您的代码。但是,我提供了示例代码来从适配器中删除项。基本上,如果要从列表的集合中添加、删除或编辑数据,需要通知适配器。
示例代码:
adapter = getListAdapter();
adapter.remove(adapter.getItem(position));
adapter.notifyDataSetChanged();
我希望这足够清楚,让您有一个好的开始。显示课程代码适应程序。您可能没有正确地将代码添加到getItem()或getCount()。@TheOriginalAndroid okay我针对完全相同的问题进行了更新。你解决了吗?
adapter = getListAdapter();
adapter.remove(adapter.getItem(position));
adapter.notifyDataSetChanged();