Applying ObjectAnimator with a Complete Example

The ObjectAnimator is a subclass of ValueAnimator and provides support for animating properties on target objects. Animators can be created from either code or resource files Some developers have negative concerns about using this class due to "reflection mechanism" of this approach.

The other issue is that you need a new ObjectAnimator for every view you want to modify since it doesn’t support simultaneous changes of several objects. However, starting from API 23, it is possible to use PropertyValuesHolder and Keyframe in resource files to create more complex animations. See here for more details.

Anyway, it worth to say that ObjectAnimator is widely used in AnimatedVectorDrawable to animate SVG due to its ability to animate a property of any type. In my opinion, in any other case, there are better solutions for animations.
Usage:

ObjectAnimator animatorX =
       ObjectAnimator.ofFloat(targetView, "property", property values);

Then we should send an instance of AnimatorUpdateListener to it.

ValueAnimator.AnimatorUpdateListener mListener;
animatorX.addUpdateListener(mListener);

The mListener should override onAnimationUpdate() function.

AnimatorUpdateListener anim2Listener = new AnimatorUpdateListener() {
      @Override
       public void onAnimationUpdate(ValueAnimator valueAnimator) {

           edtTxt.invalidate();
        }
     };

Lastly, the animation starts by the start() function of ObjectAnimator instance.

animatorX.start();

One other issue is that we can add a listener to this animation.

animatorX.addListener(new Animator.AnimatorListener() {
     @Override
     public void onAnimationStart(Animator animator) {

     }

     @Override
     public void onAnimationEnd(Animator animator) {
     Toast.makeText(activity, "End!", Toast.LENGTH_LONG).show();
     }

     @Override
     public void onAnimationCancel(Animator animator) {

     }

     @Override
     public void onAnimationRepeat(Animator animator) {

     }
   });

Lets see the topic in two examples.

Example 1: An EditText is subject to some animations. Please create a new Android Studio project and use Empty template. I create a new Java class Animator1. See below code.


Now in activity_main.xml file we add an EditText and a Button.


In MainActivity.java we should create an instance of Animator1 and an instance of AnimatorUpdateListener. This file can be completed like below.


Now it is ready to run the app and see how this animation works.

Example 2: Here we want to produce an animation like Example 2 of Animation class which is a circle animating from angle 0 to 360 degree.
Step 1- Create a new project in android studio and select Empty template. Step 2- Follow steps in Custom View in Android Apps to produce a custom view. The PieView class itself can be as follows.


Step 2- Modify the activity_main.xml file as below.


Step 3- Go to MainActivity.java and modify it like shown here.


Now its time to run the app. You probably see one animation like below!

ObjectAnimator is good for animating one or two properties simultaneously. But what if we should animate more than two properties at the same time? Please refer to ViewPropertyAnimator for a good answer!