animation of TextView's text size

scale.xml

<?xml version="1.0" encoding="utf-8"?>
<set
    xmlns:android="http://schemas.android.com/apk/res/android">
    <scale
          android:fromXScale="1.0"
          android:fromYScale="1.0"
          android:toXScale="2.0"
          android:toYScale="2.0"
          android:duration="3000"></scale>
</set>

A function into an Activity:

private void RunAnimation() 
{
    Animation a = AnimationUtils.loadAnimation(this, R.anim.scale);
    a.reset();
    TextView tv = (TextView) findViewById(R.id.firstTextView);
    tv.clearAnimation();
    tv.startAnimation(a);
}

extracted and modified from here

Animation animation=new TranslateAnimation(0,480,0,0); 
animation.setDuration(5000);
animation.setRepeatMode(Animation.RESTART);
animation.setRepeatCount(Animation.INFINITE);
text.startAnimation(animation);
// applying animation to textview object..

If you are using button event to show animation then put the code inside onClick() otherwise use override method onWindowFocusChanged(boolean hasFocus) to start animation

Use ValueAnimator class in the android

final float startSize = o; // Size in pixels
    final float endSize = 30;
    final int animationDuration = 1000; // Animation duration in ms

    ValueAnimator animator = ValueAnimator.ofFloat(startSize, endSize);
    animator.setDuration(animationDuration);

    animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator valueAnimator) {
            float animatedValue = (float) valueAnimator.getAnimatedValue();
            tv.setTextSize(animatedValue);
        }
    });

    animator.start();

refer this link ValueAnimator

Another solution is that apply scale animation on Textview or its parent layout

ScaleAnimation scaleAnimation = new ScaleAnimation(0.7f, 1.1f, 0.7f, 1.1f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f,
                   ScaleAnimation.RELATIVE_TO_SELF, 0.5f);
scaleAnimation.setDuration(600);
viewZoom.startAnimation(scaleAnimation);