How to load animator xml file on Android programatically?

Question

According to the Android developer site, we can load AnimatorSet class programatically from xml file located on the path like this: res/animator/filename.xml. So I have created a sample project and tried to see if it actually works, and it doesn't; nothing happens. It would be very nice if I can understand what is missing and/or what I have done wrong. Thanks in advance! Below is my animator xml file and Java code to load the xml:

res/animator/sample.xml:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:ordering="sequentially"
    >
  <set>
    <objectAnimator
        android:propertyName="x"
        android:duration="500"
        android:valueTo="400"
        android:valueType="intType"
        />
    <objectAnimator
        android:propertyName="y"
        android:duration="500"
        android:valueTo="300"
        android:valueType="intType"
        />
  </set>
  <objectAnimator
      android:propertyName="alpha"
      android:duration="500"
      android:valueTo="1f"
      />
</set>

And here is my Java codes to load the xml file above:

FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
  @Override public void onClick(View view) {
    // Load and start Animaton
    AnimatorSet animSet =
        (AnimatorSet) AnimatorInflater.loadAnimator(view.getContext(), R.animator.sample);
    animSet.setTarget(view);
    animSet.start();
  }
});

score 31 · Answer 1 · answered Aug 01 '16 at 12:35

You set contains another Set res/animator/sample.xml. Simplify it

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:ordering="sequentially"
    >

  <objectAnimator
      android:propertyName="alpha"
      android:duration="500"
      android:valueTo="1f"
      />
</set>

You inflate the AnimatorSet like this

AnimatorSet set = (AnimatorSet) AnimatorInflater.loadAnimator(getActivity(), R.animator.sample);
set.setTarget(fab); // set the view you want to animate
set.start();

So far, I haven't found a way to inflate objectAnimator from xml to Java. I have to wrap it inside a Set

to avoid casting, you can use Animator instead of AnimatorSet. — Mahdi Moqadasi, Nov 13 '18 at 21:07

score 4 · Accepted Answer · answered Mar 08 '18 at 07:09

This is an error in the example given in the documentation.

Try changing the android:valueType="intType" to android:valueType="floatType".

It works in case of @RaymondChenon as he is not explicitly changing the android:valueType to int so system is taking the default one float

The problem here is you are giving android:valueType="intType" in your animator which is supposed to be android:valueType="floatType" for the property android:propertyName="x" you are animating.

At runtime system look for setter for the property, you want to animate. Like in your case it will look for setX(), but as you are defining argument type of type int it causes a mismatch as there is no such method, I don't know why it doesn't lead to a crash.

Look at the properties of View class there is a method setX(float)

For further understanding, you can refer StackOverflow Question

How to load animator xml file on Android programatically?

2 Answers2