Android - 侦听器/回调，当View子项数量改变时 [英] Android - Listener/Callback for when number of View children changes
问题描述
在Android中，当给定视图的子项数动态变化时，是否可以使用/实现一个监听器来触发回调？例如，一个视图有3个直接的孩子，一个通过代码删除，我需要一个事件来说，直接孩子的数量已经改变。
In Android can one use/implement a listener that fires a callback when the number of children for a given View changes dynamically? Say for example a View has 3 immediate children, and one is removed through code, I need an event to fire to say that the number of immediate children has changed.
澄清，我不需要在View树上执行深度遍历来计数孩子，我只是想计算给定视图第一层的孩子数量。
To clarify, I don't need to perform a depth traversal on the View tree to count children, I'm just interested in counting the number of children at the first layer of a given View.
非常感谢
推荐答案
我相信你想使用 OnHierarchyChangeListener ：
当此视图中的层次结构更改时将调用的回调。每当子视图添加到此视图或从视图中删除时，层次结构都会更改。
Interface definition for a callback to be invoked when the hierarchy within this view changed. The hierarchy changes whenever a child is added to or removed from this view.
它有两个回调：
- onChildViewAdded()
- onChildViewRemoved()
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