android - RelativeLayout check runtime if is removed or not

Question

In an activity I am changing one of the ViewGroup content runtime: buttons action, other events.

At a specific case I need to check if a child is in this layout or not ( in this case the child is another RelativeLayout, which hold other views)

How can I check runtime, programmatically if child_1_RelativeLayout is there or is already removed from view tree, his parent is parentRelativeLayout

The getParent() is usefully? - not much explanation how to use it, thanks.

Answer 1

如果您存储了视图，您可以使用getParent()检查视图是否是其他视图的直接子视图。删除视图后，其父字段将被清除。例如：

ViewGroup parent = ...;
View child = ...;

assert(child.getParent() == parent); // <-- true

parent.removeView(child);

assert(child.getParent() == parent); // <-- false

Answer 2

不太确定我是否正确理解了您的问题，但是：

• 添加相对布局时，请务必先给它一个 id（在您的 layout.xml 文件中或从代码中）
• 要检查 中是否存在相关布局ViewGroup，请使用 ViewGroup 的findViewById()方法（继承自View）并将您提供给相关布局的 id 传递给它
• 如果返回null，则相对布局不存在，否则findViewById()会找到

所以简而言之，findViewById()它不仅是为一个 Activity 定义的，而且你可以在任何你想用作搜索起点的视图上调用它。