什么是@android之间的区别：和android？ [英] What's the difference between @android: and ?android:

问题描述

什么

android:color="@android:color/black"

和

style="?android:attr/borderlessButtonStyle" 

有什么之间的差异 @ 和？？

这是这些问题是ungoogleable一个，或 ogooglebar 。

This is one of those questions which is ungoogleable, or ogooglebar.

推荐答案

（从这个回答和评论）

prefixing带问号的标识表明您要访问的是在一个风格的主题定义的样式属性，而不是硬编码的属性，如<一个解释href="http://developer.android.com/guide/topics/resources/accessing-resources.html#ReferencesToThemeAttributes"相对=nofollow>引用样式属性。

Prefixing the ID with a question mark indicates that you want to access a style attribute that's defined in a style theme, rather than hard-coding the attribute, as explained in Referencing Style Attributes.

更具体地说，？意味着间接额外的水平。把它看成是解引用主题属性来获取它所指向的资源，而不是指属性本身。你看这与Android：ATTR /富

More specifically, the ? implies an extra level of indirection. Think of it as dereferencing a theme attribute to fetch the resource it points to rather than referring to the attribute itself. You see this with ?android:attr/foo

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