How to create a floating action button (FAB) in android, using AppCompat v21?

Question

I would like to create a floating action button (to add items to a listview), like google calendar, maintaining compatibility with pre-lollipop Android versions (before 5.0)

Answer 1

There is no longer a need for creating your own FAB nor using a third party library, it was included in AppCompat 22.

https://developer.android.com/reference/android/support/design/widget/FloatingActionButton.html

Just add the new support library called design in in your gradle-file:

compile 'com.android.support:design:22.2.0'

...and you are good to go:

<android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:layout_margin="16dp"
        android:clickable="true"
        android:src="@drawable/ic_happy_image" />