Creating a 3D flip animation in Android using XML

Here is the answer, though it only works with 3.0 and above.

1) Create a new resources folder called "animator".

2) Create a new .xml file which I will call "flipping". Use the following xml code:

<?xml version="1.0" encoding="utf-8"?>
<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
    android:valueFrom="0" android:valueTo="360" android:propertyName="rotationY" >
</objectAnimator>

No, the objectAnimator tags do not start with an uppercase "O".

3) Start the animation with the following code:

ObjectAnimator anim = (ObjectAnimator) AnimatorInflater.loadAnimator(mContext, R.animator.flipping); 
anim.setTarget(A View Object reference goes here i.e. ImageView);
anim.setDuration(3000);
anim.start();

I got all this from here.

Since the answers to this question are fairly dated, here is a more modern solution relying on ValueAnimators. This solution implements a true, visually appealing 3D-flip, because it not just flips the view, but also scales it while it is flipping (this is how Apple does it).

First we set up the ValueAnimator:

mFlipAnimator = ValueAnimator.ofFloat(0f, 1f);
mFlipAnimator.addUpdateListener(new FlipListener(frontView, backView));

And the corresponding update listener:

public class FlipListener implements ValueAnimator.AnimatorUpdateListener {

    private final View mFrontView;
    private final View mBackView;
    private boolean mFlipped;

    public FlipListener(final View front, final View back) {
        this.mFrontView = front;
        this.mBackView = back;
        this.mBackView.setVisibility(View.GONE);
    }

    @Override
    public void onAnimationUpdate(final ValueAnimator animation) {
        final float value = animation.getAnimatedFraction();
        final float scaleValue = 0.625f + (1.5f * (value - 0.5f) * (value - 0.5f));

        if(value <= 0.5f){
            this.mFrontView.setRotationY(180 * value);
            this.mFrontView.setScaleX(scaleValue);
            this.mFrontView.setScaleY(scaleValue);
            if(mFlipped){
                setStateFlipped(false);
            }
        } else {
            this.mBackView.setRotationY(-180 * (1f- value));
            this.mBackView.setScaleX(scaleValue);
            this.mBackView.setScaleY(scaleValue);
            if(!mFlipped){
                setStateFlipped(true);
            }
        }
    }

    private void setStateFlipped(boolean flipped) {
        mFlipped = flipped;
        this.mFrontView.setVisibility(flipped ? View.GONE : View.VISIBLE);
        this.mBackView.setVisibility(flipped ? View.VISIBLE : View.GONE);
    }
}

That's it!

After this setup you can flip the views by calling

mFlipAnimator.start();

and reverse the flip by calling

mFlipAnimator.reverse();

If you want to check if the view is flipped, implement and call this function:

private boolean isFlipped() {
    return mFlipAnimator.getAnimatedFraction() == 1;
}

You can also check if the view is currently flipping by implementing this method:

private boolean isFlipping() {
    final float currentValue = mFlipAnimator.getAnimatedFraction();
    return (currentValue < 1 && currentValue > 0);
}

You can combine the above functions to implement a nice function to toggle the flip, depending on if it is flipped or not:

private void toggleFlip() {
    if(isFlipped()){
        mFlipAnimator.reverse();
    } else {
        mFlipAnimator.start();
    }
}

That's it! Simple and easy. Enjoy!