Android的<merge>的目的是什么?XML 布局中的标记? [英] What is the purpose of Android's <merge> tag in XML layouts?

问题描述

我在 Romain Guy 的帖子上阅读了<merge/> 标签，但我还是不明白它有什么用处.它是 <Frame/> 标签的替代品，还是像这样使用:

I've read Romain Guy's post on the <merge /> tag, but I still don't understand how it's useful. Is it a sort-of replacement of the <Frame /> tag, or is it used like so:

<merge xmlns:android="....">
<LinearLayout ...>
    .
    .
    .
</LinearLayout>
</merge>

然后 另一个文件中的代码?

then <include /> the code in another file?

推荐答案

<merge/> 很有用，因为它可以摆脱不需要的 ViewGroups，即简单地用于包装其他观点并且本身没有任何意义.

<merge/> is useful because it can get rid of unneeded ViewGroups, i.e. layouts that are simply used to wrap other views and serve no purpose themselves.

例如，如果您要 另一个文件中的布局而不使用合并，则这两个文件可能如下所示:

For example, if you were to <include/> a layout from another file without using merge, the two files might look something like this:

layout1.xml:

layout1.xml:

<FrameLayout>
   <include layout="@layout/layout2"/>
</FrameLayout>

layout2.xml:

layout2.xml:

<FrameLayout>
   <TextView />
   <TextView />
</FrameLayout>

在功能上等同于这个单一布局:

which is functionally equivalent to this single layout:

<FrameLayout>
   <FrameLayout>
      <TextView />
      <TextView />
   </FrameLayout>
</FrameLayout>

layout2.xml 中的 FrameLayout 可能没有用. 有助于摆脱它.下面是使用合并的样子(layout1.xml 不会改变):

That FrameLayout in layout2.xml may not be useful. <merge/> helps get rid of it. Here's what it looks like using merge (layout1.xml doesn't change):

layout2.xml:

layout2.xml:

<merge>
   <TextView />
   <TextView />
</merge>

这在功能上等同于这个布局:

This is functionally equivalent to this layout:

<FrameLayout>
   <TextView />
   <TextView />
</FrameLayout>

但是由于您使用的是 <include/>，您可以在其他地方重用布局.它不必仅用于替换 FrameLayouts - 您可以使用它来替换任何对视图外观/行为方式没有帮助的布局.

but since you are using <include/> you can reuse the layout elsewhere. It doesn't have to be used to replace only FrameLayouts - you can use it to replace any layout that isn't adding something useful to the way your view looks/behaves.

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