将特定的ListView项滚动到视图中 [英] Scroll a particular ListView item into view

问题描述

在我的应用程序中，我有一个ListView.列表中每个项目的数据都是SomeItem类的实例.该列表具有一个自定义ArrayAdapter，该自定义ArrayAdapter具有一个自定义视图以显示每个项目的各个字段并覆盖getView()方法.用于初始化列表视图的骨架代码:

In my application, I have a ListView. The data for each item in the list is an instance of the SomeItem class. The list has a custom ArrayAdapter which has a custom view to display various fields of each items and overrides the getView() method. Skeleton code for the initialization of the list view:

ListView listView = (ListView) foo.getViewById(R.id.listView);

ArrayAdapter<SomeItem> adapter = new ArrayAdapter<SomeItem>(activity, R.layout.listItemView, R.id.textView) {
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Code to build the view with multiple child views
    }
}

现在假设我有一个SomeItem实例.它的关联视图可能在屏幕上显示的ListView部分中，也可能不在该部分中.如果不是，如何获取ListView将该特定项目滚动到视图中?

Now assume I have a SomeItem instance. Its associated view may or may not be in the portion of the ListView which is shown on screen. If it is not, how can I get the ListView to scroll this particular item into view?

我发现的唯一相关的方法是ListView#requestChildRectangleOnScreen()，它要求我提供我没有的子视图.我有用于适配器的物品.因此，我仍然不确定如何将其组合在一起.有指针吗?

The only somewhat related method I’ve found is ListView#requestChildRectangleOnScreen(), which requires me to provide a child view which I don’t have. I have the item for the adapter. So I’m still not sure how to piece this together. Any pointers?

推荐答案

您可以尝试以下操作:

1. 计算要显示的SomeItem项目的位置.您可以通过遍历传递给适配器的SomeItem列表来完成此操作.

1. Calculate the position of the SomeItem item you want to make visible. You can do this by iterating over the list of SomeItems that you pass to the adapter.

使用listView.getFirstVisiblePosition()，listView.getLastVisiblePosition()和计算出的位置来检查该项目在列表中是否可见.

Use listView.getFirstVisiblePosition(), listView.getLastVisiblePosition() and the calculated position to check if the item is visible on the list.

如果该项目不可见，请调用listView.smoothScrollToPosition(calculatedPosition)使listView滚动至该项目.

If the item is not visible, make listView scroll to it by calling listView.smoothScrollToPosition(calculatedPosition).

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