所以，我有一个ListView我在TodayFragment上显示。有TodayTaskAdapter，可以自定义此列表。当加载actvity时，由于列表需要花费很多时间。并减慢应用程序。问题是：
getView()方法中进行操作
化背景; 我还没完成它。需要帮助。
public class TodayFragment extends AbstractTabFragment
{
public static final String TODAY_PAGE = "TODAY_PAGE";
private static final int LAYOUT = R.layout.fragment_today;
private ListView task_list;
private TodayTaskAdapter today_task_adapter;
private Event event;
private Event event1;
private Event event3;
private Event event4;
private Event event5;
private Event event6;
private Event event7;
private Event event8;
private Event event9;
public static TodayFragment newInstance(int page, Context context)
{
Bundle args = new Bundle();
args.putInt(TODAY_PAGE, page);
TodayFragment fragment = new TodayFragment();
fragment.setArguments(args);
fragment.setContext(context);
fragment.setTitle(context.getString(R.string.tab_today_name));
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
view = inflater.inflate(LAYOUT, container, false);
task_list = (ListView) view.findViewById(R.id.tasks_list);
today_task_adapter = new TodayTaskAdapter(getActivity(), R.layout.today_list_item);
eventCreation();
today_task_adapter.add(new EventTypeSection("Schedule"));
today_task_adapter.add(event);
today_task_adapter.add(event1);
today_task_adapter.add(event3);
today_task_adapter.add(new EventTypeSection("ToDo"));
today_task_adapter.add(event4);
today_task_adapter.add(event5);
today_task_adapter.add(new EventTypeSection("Work Task"));
today_task_adapter.add(event6);
today_task_adapter.add(event7);
today_task_adapter.add(new EventTypeSection("Birthday"));
today_task_adapter.add(event8);
today_task_adapter.add(event9);
task_list.setAdapter(today_task_adapter);
return view;
}
private void eventCreation()
{
event = new Schedule(1,"Algorythm Theory", ScheduleType.LESSON, "10:20 AM", "11:55 AM", "07.01.2017", EventType.SCHEDULE, "Waiting", 79);
event1 = new Schedule(2,"Object-oriented programming", ScheduleType.LABORATORY_WORK, "12:00 AM", "01:30 PM", "07.01.2017", EventType.SCHEDULE, "Waiting", 63);
event3 = new Schedule(2,"Aplied Math", ScheduleType.EXAM, "01:50 PM", "03:35 PM", "07.01.2017", EventType.SCHEDULE, "Waiting", 17);
event4 = new ToDo(5,"Clean house", "09:30 AM", "03:35 PM", "07.01.2017", EventType.TODO, "Waiting", 91);
event5 = new ToDo(7,"Buy grocery and other things", "01:30 AM", "02:25 PM", "07.01.2017", EventType.TODO, "Waiting", 23);
event6 = new WorkTask(5,"Refactoring", "09:30 AM", "01:35 PM", "07.01.2017", EventType.WORKTASK, "Waiting", 81);
event7 = new WorkTask(7,"Build database", "04:30 PM", "05:25 PM", "07.01.2017", EventType.WORKTASK, "Waiting", 33);
event8 = new Birthday(8,"Taras's birthday", "09:30 AM", "01:35 PM", "07.01.2017", EventType.BIRTHDAY, "Waiting", 71, new Location(1, 2, "Roksolany", "Lviv", "Ukraine"));
event9 = new Birthday(9,"John's birthday", "04:30 PM", "05:25 PM", "07.01.2017", EventType.BIRTHDAY, "Waiting", 53, new Location(1, 2, "Roksolany", "Lviv", "Ukraine"));
}
}
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.content.ContextCompat;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import com.example.twinkle94.dealwithit.R;
import com.example.twinkle94.dealwithit.events.Event;
import com.example.twinkle94.dealwithit.events.task_types.Schedule;
import com.example.twinkle94.dealwithit.events.type_enums.EventType;
import java.util.ArrayList;
import java.util.List;
public class TodayTaskAdapter extends ArrayAdapter
{
private final String NAME = TodayTaskAdapter.class.getSimpleName();
private static final int TYPE_HEADER = 0;
private static final int TYPE_LIST = 1;
private List<Item> list_of_tasks = new ArrayList<>();
public TodayTaskAdapter(Context context, int resource)
{
super(context, resource);
}
public void add(Item event)
{
list_of_tasks.add(event);
}
@Override
public int getCount()
{
return list_of_tasks.size();
}
@Nullable
@Override
public Item getItem(int position)
{
return list_of_tasks.get(position);
}
@Override
public int getItemViewType(int position)
{
return getItem(position).getType() == EventType.NO_TYPE ?
RowType.HEADER_ITEM.ordinal()
:
RowType.LIST_ITEM.ordinal();
}
@Override
public int getViewTypeCount()
{
return RowType.values().length;
}
@NonNull
@Override
public View getView(int position, View convertView, @NonNull ViewGroup parent)
{
EventViewHolder eventViewHolder;
// Get the data item type for this position
int type = getItemViewType(position);
if(convertView == null)
{
eventViewHolder = new EventViewHolder();
// Inflate XML layout based on the type
convertView = getInflatedLayoutForType(type, parent);
switch (type)
{
case TYPE_HEADER:
initHeader(convertView, eventViewHolder);
break;
case TYPE_LIST:
initViews(convertView, eventViewHolder);
break;
}
convertView.setTag(eventViewHolder);
}
else
{
eventViewHolder = (EventViewHolder) convertView.getTag();
}
//set all views with values from list
setViewValues(position, eventViewHolder);
return convertView;
}
private void setViewValues(int position, EventViewHolder eventViewHolder)
{
Item event = getItem(position);
int type_color;
String task_title;
String from_time;
String to_time;
String importance;
String interest;
if (event != null)
{
switch (event.getType())
{
case SCHEDULE:
type_color = ContextCompat.getColor(getContext(), R.color.colorTypeSchedule);
task_title = ((Event)(event)).getTitle();
String schedule_type = ((Schedule)(event)).getScheduleType().toString();
int schedule_type_image = getSchedule_type_image(event);
from_time = ((Event)(event)).getTime_start();
to_time = ((Event)(event)).getTime_end();
importance = Integer.toString(((Event)(event)).getImportance()) + "%";
interest = Integer.toString(((Event)(event)).getImportance() + 9) + "%";
eventViewValues(eventViewHolder, type_color, task_title, schedule_type_image, schedule_type, from_time, to_time, importance, interest, View.VISIBLE, View.VISIBLE);
break;
case TODO:
type_color = ContextCompat.getColor(getContext(), R.color.colorTypeToDo);
task_title = ((Event)(event)).getTitle();
from_time = ((Event)(event)).getTime_start();
to_time = ((Event)(event)).getTime_end();
importance = Integer.toString(((Event)(event)).getImportance()) + "%";
interest = Integer.toString(((Event)(event)).getImportance() + 9) + "%";
eventViewValues(eventViewHolder, type_color, task_title, 0, "", from_time, to_time, importance, interest, View.GONE, View.GONE);
break;
case WORKTASK:
type_color = ContextCompat.getColor(getContext(), R.color.colorTypeWorkTasks);
task_title = ((Event)(event)).getTitle();
from_time = ((Event)(event)).getTime_start();
to_time = ((Event)(event)).getTime_end();
importance = Integer.toString(((Event)(event)).getImportance()) + "%";
interest = Integer.toString(((Event)(event)).getImportance() + 9) + "%";
eventViewValues(eventViewHolder, type_color, task_title, 0, "", from_time, to_time, importance, interest, View.GONE, View.GONE);
break;
case BIRTHDAY:
type_color = ContextCompat.getColor(getContext(), R.color.colorTypeBirthday);
task_title = ((Event)(event)).getTitle();
from_time = ((Event)(event)).getTime_start();
to_time = ((Event)(event)).getTime_end();
importance = Integer.toString(((Event)(event)).getImportance()) + "%";
interest = Integer.toString(((Event)(event)).getImportance() + 9) + "%";
eventViewValues(eventViewHolder, type_color, task_title, 0, "", from_time, to_time, importance, interest, View.GONE, View.GONE);
break;
case NO_TYPE:
String type = ((EventTypeSection) getItem(position)).getTitle();
eventViewHolder.headerText.setText(type);
switch(type)
{
case "Schedule":
eventViewHolder.headerText.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.colorTypeSchedule));
break;
case "ToDo":
eventViewHolder.headerText.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.colorTypeToDo));
break;
case "Work Task":
eventViewHolder.headerText.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.colorTypeWorkTasks));
break;
case "Birthday":
eventViewHolder.headerText.setBackgroundColor(ContextCompat.getColor(getContext(), R.color.colorTypeBirthday));
break;
}
break;
//TODO: add default, when task have no type.
}
}
}
private int getSchedule_type_image(Item event)
{
int schedule_type_image = R.drawable.ic_lesson_type;
switch(((Schedule)(event)).getScheduleType())
{
case LESSON:
schedule_type_image = R.drawable.ic_lesson_type;
break;
case EXAM:
schedule_type_image = R.drawable.ic_exam_schedule_type;
break;
case LABORATORY_WORK:
schedule_type_image = R.drawable.ic_lab_work_schedule_type;
break;
}
return schedule_type_image;
}
//TODO: overload method with less parameters for different types of tasks.
private void eventViewValues(EventViewHolder eventViewHolder, int type_color, String task_title, int scheduleTypeImage, String schedule_type,
String from_time, String to_time, String importance, String interest,
int task_type_visibility, int task_type_image_visibility)
{
eventViewHolder.type_color.setBackgroundColor(type_color);
eventViewHolder.task_title.setText(task_title);
eventViewHolder.task_type.setText(schedule_type);
eventViewHolder.task_type_image.setImageResource(scheduleTypeImage);
eventViewHolder.task_type.setVisibility(task_type_visibility);
eventViewHolder.task_type_image.setVisibility(task_type_image_visibility);
eventViewHolder.from_title.setText("From");
eventViewHolder.from_time.setText(from_time);
eventViewHolder.from_image.setImageResource(R.drawable.ic_from_time);
eventViewHolder.to_title.setText("To");
eventViewHolder.to_time.setText(to_time);
eventViewHolder.to_image.setImageResource(R.drawable.ic_to_time);
eventViewHolder.importance.setText(importance);
eventViewHolder.importance_image.setImageResource(R.drawable.ic_importance_icon);
eventViewHolder.interest.setText(interest);
eventViewHolder.interest_image.setImageResource(R.drawable.ic_interest_today_page);
}
private View getInflatedLayoutForType(int type, ViewGroup parent)
{
LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View inflated_view = null;
switch(type)
{
case TYPE_HEADER:
inflated_view = layoutInflater.inflate(R.layout.today_list_header, parent, false);
break;
case TYPE_LIST:
inflated_view = layoutInflater.inflate(R.layout.today_list_item, parent, false);
break;
}
return inflated_view;
}
private void initHeader(View row, EventViewHolder eventViewHolder)
{
eventViewHolder.headerText = (TextView) row.findViewById(R.id.tasks_title);
}
private void initViews(View row, EventViewHolder eventViewHolder)
{
eventViewHolder.type_color = row.findViewById(R.id.type_color);
eventViewHolder.task_title = (TextView) row.findViewById(R.id.task_title);
eventViewHolder.task_type = (TextView) row.findViewById(R.id.task_type);
eventViewHolder.task_type_image = (ImageView) row.findViewById(R.id.lesson_type);
eventViewHolder.from_title = (TextView) row.findViewById(R.id.from_title);
eventViewHolder.from_time = (TextView) row.findViewById(R.id.from_time);
eventViewHolder.from_image = (ImageView) row.findViewById(R.id.from_time_icon);
eventViewHolder.to_title = (TextView) row.findViewById(R.id.to_title);
eventViewHolder.to_time = (TextView) row.findViewById(R.id.to_time);
eventViewHolder.to_image = (ImageView) row.findViewById(R.id.to_time_icon);
eventViewHolder.importance = (TextView) row.findViewById(R.id.importance_percent);
eventViewHolder.importance_image = (ImageView) row.findViewById(R.id.importance_icon);
eventViewHolder.interest = (TextView) row.findViewById(R.id.interest_percent);
eventViewHolder.interest_image = (ImageView) row.findViewById(R.id.interest_icon);
}
private static class EventViewHolder
{
View type_color;
TextView task_title;
TextView task_type;
ImageView task_type_image;
TextView from_title;
TextView from_time;
ImageView from_image;
TextView to_title;
TextView to_time;
ImageView to_image;
TextView importance;
ImageView importance_image;
TextView interest;
ImageView interest_image;
//Header text
TextView headerText;
}
private enum RowType
{
HEADER_ITEM, LIST_ITEM
}
}
答案 0 :(得分：1)
由于各种原因，列表可能需要很长时间才能加载：数据大小，与后端服务器的连接速度慢，计算需求高等等。通常这些耗时的任务只需要一些时间而且没有任何内容我们可以做到这一点，除了尽量减少对用户的影响。
使用AsyncTask，Loader等进行后台处理的目标是花费一个耗时的任务并将其从运行用户界面的线程（UI线程）移开尽可能重叠处理，以便应用程序看起来不会挂起。＆＃34;所以，请尽快启动AsyncTask。根据您的应用程序，可以在用户需要查看结果数据时完成处理。如果没有，那么你可能不得不抛出一个ProgressBar让他们知道他们需要等一下。 onPreExecute()的{{1}}，onProgressUpdate()和onPostExecute()方法将帮助您与用户（在UI线程上）沟通您的应用在获取数据方面取得的进展。请参阅documentation。
另请查看this example。在设置AsyncTask适配器后立即调用AsyncTask。这是一个常见的地方。这将在你的片段中。 （ListView不是正确的地方。）
getView()如果您要显示大量数据，那么您可能需要实现一些逻辑来进行无限滚动，您可以在获取更多数据之前显示一两页数据。只需搜索＆＃34; listView无休止的滚动＆＃34;有关这方面的更多信息。
我希望这会有所帮助。