Using android studio's tools attributes for quick design review

Do you know layout tools attributes? Android Studio supports a variety of XML attributes in the tools namespace that enable design-time features. We import it sometimes without really knowing what it is for.

xmlns:tools="http://schemas.android.com/tools"

Tools namespace is used to enable design-time and complie time features.When you build your app, the build tools remove these attributes so there is no effect on your APK size or runtime behavior. We use tools:text(Use it if not already, than hard coding text with android:text for design checks) with a plain text or with a label from strings.xml file. That's it. Do you know that actually tools attribute is very powerful and can be helpful while designing?

Show Time!!

Fragment

• tools:layout This attribute is used only by tags and informs editor about the layout that should be drawn by layout preview inside the fragment.

  ##TODO Images

  <fragment android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:id="@+id/fragment"
              tools:layout="@layout/fragment_layout"/>

RecyclerView

• tools:listitem This attribute allows us to replace the randoms lines of a “List Item” into a "Real Item" we have built for the actual application, directly shows inside the editor.
• | tools:listheader | tools:listfooter You can use these attributes to set header and footer layouts of a ListView.
• tools:itemCount You can adjust the size of the list item.

 <android.support.v7.widget.RecyclerView
           android:layout_width="match_parent"
           android:layout_height="0dp"
           app:layout_constraintTop_toTopOf="parent"
           app:layout_constraintStart_toStartOf="parent"
           app:layout_constraintEnd_toEndOf="parent"
           tools:listitem="@layout/sample_card_view_item"
           tools:itemCount="3"
           app:layout_constraintBottom_toBottomOf="parent"/>

"@tools:sample/" resources

These are the most useful resources to inject placeholder data or images into our views. Currently, Android Studio offers following types of predefined data that can be injected into our view elements.

Attribute value	Description of placeholder data
@tools:sample/full_names	Full names that are randomly generated from the combination of
@tools:sample/first_names	Common first names.
@tools:sample/last_names	Common last names.
@tools:sample/cities	Names of cities from across the world.
@tools:sample/us_zipcodes	Randomly generated US zipcodes.
@tools:sample/us_phones	Randomly generated phone numbers with the following format: (800) 555-xxxx.
@tools:sample/lorem	Placeholder text that is derived from Latin.
@tools:sample/date/day_of_week	Randomized dates and times for the specified format.
@tools:sample/date/ddmmyy
@tools:sample/date/mmddyy
@tools:sample/date/hhmm
@tools:sample/date/hhmmss
@tools:sample/avatars	Vector drawables that you can use as profile avatars.
@tools:sample/backgrounds/scenic	Images that you can use as backgrounds.