Why AndroidStudio shows warning "Namespace declaration is never used"?
android, android-layout, xml, xml-namespaces
Solution
This is because you don't have anything with `tools` namespace actually declared in your xml.
Look at the `android` namespace, you have 3 elements with that namespace, but none for `tools`.
The namespace `tools` (http://schemas.android.com/tools) is used for the GUI designer and is not used for running apps on Android devices so you can safely remove it.
Problem
This is my layout: ``` <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal" > </LinearLayout> ``` Taked from the android official training In the second line, AndroidStudio shows this warning: ``` Namespace declaration is never used ``` Why this happens? Thank you.