我如何选择convertview重用? [英] how do i choose convertview to reuse?

问题描述

上下文
我想要一个列表项具有3种明显不同的布局的列表项，因此我根据要显示的项的类型来创建适配器，以创建适当的视图.
例如我想列出一些图像，文本和数字，每个都有一些标题. 我知道在
public View getView(int position, View convertView, ViewGroup parent)
convertView表示重复使用不再可见的listItems视图.

Context
I want to have a list with 3 significantly different layouts for list items so I make my adapter that based on type of item to display creates appropriate view.
e.g. i want to list some images, texts and numbers, each with some title. I know that in
public View getView(int position, View convertView, ViewGroup parent)
the convertView stands for reusing no longer visible listItems views.

问题
如何选择convertView或如何控制进入那里的东西?

Question
How can I choose the convertView or how can i control what i get in there?

问题来自于不同的listItems视图，假设我的列表以图像listItem开头，然后出现很多文本listItems和数字listItems，而后面有100个listItems是第二个图像. 我假设向下滚动列表(在getView(...)调用中)不为null的第一个convertView是带有图像的图像，并且由于我需要显示文本listItem或数字listItem的视图，因此无法使用它.然后我想在每个下一个getView(...)调用中，convertView都是与先前调用中相同的图像listItem，因为我以前没有使用过它.

The problem comes with different listItems views, assume I have my list starting with an image listItem, then comes a lot of text listItems and number listItems and 100 listItems later comes second image. I assume that while scrolling down the list, (in getView(...) calls) the first convertView that is not null is the one with image, and since i need a view to display text listItem or number listItem I cannot use it. Then i guess that in every next getView(...) call the convertView is that same image listItem as in previous calls because i didn't use it before.

未使用的文本listItems和数字listItems卡住了，滚动列表时，我需要继续创建新视图，这是我要防止的事情.

The unused text listItems and number listItems stuck up and when scrolling the list I need to keep creating new views, this is what i want to prevent.

推荐答案

您需要让适配器的视图回收器知道不止一种布局，以及如何区分每一行的两种布局.只需覆盖以下方法:

You need to let the adapter's view recycler know that there is more than one layout and how to distinguish between the two for each row. Simply override these methods:

我在这里说了2种不同的布局.如果您还有更多，请使用枚举来区分它们.

Here i have said for 2 different layouts. If you have more use an enum to distinguish them.

@Override
public int getItemViewType(int position) {
    // Define a way to determine which layout to use, here it's just evens and odds.
    return position % 2;
}

@Override
public int getViewTypeCount() {
    return 2; // Count of different layouts (Change according to your requirment)
}

将getItemViewType()合并到getView()中，如下所示:

Incorporate getItemViewType() inside getView(), like this:

if (convertView == null) {
    // You can move this line into your constructor, the inflater service won't change.
    mInflater = (LayoutInflater) mContext.getSystemService(LAYOUT_INFLATER_SERVICE);
    if(getItemViewType(position) == 0)
        convertView = mInflater.inflate(R.layout.listview_item_product_1, parent,false);
    else
        convertView = mInflater.inflate(R.layout.listview_item_product_2,parent,false);
    // etc, etc...

在Google Talks上观看Android的Romain Guy讨论查看回收站.

Watch Android's Romain Guy discuss the view recycler at Google Talks.

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