17.11 Tools Visibility Toggles

When reviewing the content of an Android Studio XML layout file in Code mode you will notice that many of the attributes that define how a view is to appear and behave begin with the android: prefix. This indicates that the attributes are set within the android namespace and will take effect when the app is run. The following excerpt from a layout file, for example, sets a variety of attributes on a Button view:

<Button

    android:id="@+id/button"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"

    android:text="Button"

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In addition to the android namespace, Android Studio also provides a tools namespace. When attributes are set within this namespace, they only take effect within the layout editor preview. While designing a layout you might, for example, find it helpful...