自定义列表视图scrollin不顺畅 [英] Custom listview scrollin isn't smooth

问题描述

我创建这是一个事实，即列表不会平滑滚动伟大的工作，除了自定义列表视图。它的震荡和缓慢的。

I've created a custom listview which is working great apart from the fact that the list doesn't smooth scroll. Its choppy and slow.

这里的code，我填充的ListView：

Here's the code where I populate the listview:

@Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View v = convertView;
            if (v == null) {
                LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = vi.inflate(R.layout.listitem, null);
        }

        FilmRecord film = films.get(position);
        if (film != null) {
            TextView filmTitle = (TextView) v.findViewById(R.id.filmtitle);
            TextView filmShowingDate = (TextView) v.findViewById(R.id.filmshowingtime);
            TextView filmAdded = (TextView) v.findViewById(R.id.filmadded);
            TextView filmLocations = (TextView) v.findViewById(R.id.filmlocations);
            TextView filmDescription = (TextView) v.findViewById(R.id.filmdescription);
            TextView filmProvider = (TextView) v.findViewById(R.id.filmprovider);
            TextView filmTicketUrl = (TextView) v.findViewById(R.id.filmticketurl);


            if (filmTitle != null) {
                filmTitle.setText(film.filmTitle);
            }

            if(filmDescription != null) {
                filmDescription.setText(film.filmDescription );
            }

            if(filmLocations != null) {
                filmLocations.setText(film.filmLocations );
            }

            if(filmShowingDate != null) {
                filmShowingDate.setText("Showing: " + film.filmShowingDate );
            }

            if(filmAdded != null) {
                filmAdded.setText("Added on: " + film.filmAdded );
            }

            if(filmProvider != null) {
                filmProvider.setText(film.filmProvider );
            }

            if(filmTicketUrl != null) {
                filmTicketUrl.setText(film.filmTicketUrl );
            }
        }

        //Check who the provider is and set the imageview to provider logo
        ImageView imageView = (ImageView) v.findViewById(R.id.providerImage);
        if(film.filmProvider.equals("Cineworld")) {
            Log.d("Provider", "Provider is Cineworld");
            imageView.setImageResource(R.drawable.cineworld);
        }
        else if(film.filmProvider.equals("Show Film Fist")){
            Log.d("Provider", "Provider is Show Film Fist");
            imageView.setImageResource(R.drawable.show_film_first);
        }

        return v;
    }

有没有人创建自定义列表视图时，也有类似的问题？任何帮助一如既往将是非常美联社preciated：）

Has anyone had similar issues when creating a custom listview? Any help as always would be much appreciated :)

推荐答案

您需要使用 ViewHolder 办法。

因为ID找到View还需要时间来执行。

because finding the View by id also takes time to execute.

使用 ViewHolder 办法，你将能够最大限度地减少通过缓存的意见发现通过ID查看过程中产生的负荷：）

by using ViewHolder approach you will be able to minimize the load created during finding View by id by caching the views :)

这里是很好的教程如何做到这一点。

Here is nice tutorial how to do that.

什么ViewHolder办法做的是：

假设你有你的的ListView 在一个时间4可见项。你必须充气查看 4的时间和 findViewById（）只有4次，即使你滚动到第1000个项目的ListView 。

Say you have 4 visible items in your ListView at a time. You have to inflate the View 4 time and findViewById() 4 times only even if you scroll to 1000th item in ListView.

但是，如果你不使用 ViewHolder ，你已经把

But if you don't use ViewHolder and you have put

if (v == null) {
   LayoutInflater vi = ...;
}else{
   //... other implementation 
}

您已经吹大查看只有4次，但 findViewById（）将被称为每时间在 getView（）被称为（通常当的ListView 滚动）。

You have to inflate the View 4 time only, but findViewById() will be called every time when the getView() is called (usually when ListView is scrolled).

编程快乐！

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