How to use StateListAnimator?

Question

From the docs:

The new StateListAnimator class lets you define animators that run when the state of a view changes. The following example shows how to define an StateListAnimator as an XML resource:

<!-- animate the translationZ property of a view when pressed --> <selector xmlns:android="http://schemas.android.com/apk/res/android">  
  <item android:state_pressed="true">
    <set>
      <objectAnimator android:propertyName="translationZ"
        android:duration="100"
        android:valueTo="2"
        android:valueType="floatType"/>
        <!-- you could have other objectAnimator elements
             here for "x" and "y", or other properties -->
    </set>   
  </item>   
  <item android:state_enabled="true"
    android:state_pressed="false"
    android:state_focused="true">
    <set>
      <objectAnimator android:propertyName="translationZ"
        android:duration="100"
        android:valueTo="2"
        android:valueType="floatType"/>
    </set> 
  </item> 
</selector>

However, it says nothing about how to actually use this xml file. There seems to be no method on the Resources class to get a StateListAnimator, and the StateListAnimator class does not provide any info either.

How can we use this?

Answer 1

In Android L a new xml attribute has been added for View :

android:stateListAnimator   : Sets the state-based animator for the View.

Additionally for instantiating StateListAnimator object programmatically a new method :

loadStateListAnimator(Context context, int id)

has been added to AnimatorInflater .

These can be found on Android L developer preview documentation package.

Answer 2

I use this code in java and works fine

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {
            crd.setStateListAnimator(AnimatorInflater.loadStateListAnimator(ctx,
                    R.drawable.card_smooth_shadow));
}

And my animator/card_smooth_shadow.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_pressed="true">
    <set>
        <objectAnimator android:propertyName="translationZ"
            android:duration="@android:integer/config_shortAnimTime"
            android:valueTo="10dp"
            android:valueType="floatType"/>
    </set>
</item>
<item
    android:state_pressed="false">
    <set>
        <objectAnimator android:propertyName="translationZ"
            android:duration="100"
            android:valueTo="2dp"
            android:valueType="floatType"/>
    </set>
</item>

RESULT