what is main "?" "@" ":" symbol in android xml - Stack Overflow

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I can't find any documentation or something like that about "?" "@" ":" symbol in android xml. It often using in themes and styles in android development. What is symbols exactly means can't understand.

Please give some docs?

I can't find any documentation or something like that about "?" "@" ":" symbol in android xml. It often using in themes and styles in android development. What is symbols exactly means can't understand.

Please give some docs?

• android
• xml

Share Improve this question Follow edited Mar 10 at 15:05 TylerH 21.1k7979 gold badges7979 silver badges114114 bronze badges asked Mar 10 at 7:34 AbbosAbbos 1 1

• 1 Documentation – tomerpacific Commented Mar 10 at 7:49

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2 Answers 2

Sorted by: Reset to default 1

These are pretty simple actually.

1. The "@" is the symbol which is used for resources or while declaring id, like @string/hello , @+id/button, or @drawable/my_drawable .

2. The "?" is refers to a theme attribute or styleable content, like if you want to define any theme attribute in styles like color etc, you would use this. eg ?attr/colorPrimary .

3.And the last ":" is commonly used in namespaces in XML, it is used to seperate the prefix in the namespace. for eg. android:layout_width="match_parent" . Hence you would know that android is the prefix in the namespace declared.

Those links may help you,plz check.

https://developer.android/guide/topics/resources/providing-resources#ResourcesFromXml

https://developer.android/studio/write/vector-asset-studio#referring

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