Animation fade in and out

Using this code I only have a fade in, I'm looking for how to add a fade out as well. I've added another xml called "fadeout" but I can't integrate it in my code.

ImageView imageView = (ImageView)findViewById(R.id.imageView);
Animation fadeInAnimation = AnimationUtils.loadAnimation(this, R.anim.fadein);
imageView.startAnimation(fadeInAnimation);

button1.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
        imageView.startAnimation(fadeInAnimation);
    }
}

fadein.xml

<?xml version="1.0" encoding="UTF-8"?>
  <set xmlns:android="http://schemas.android.com/apk/res/android">
    <alpha android:fromAlpha="0.0" android:toAlpha="1.0" 
     android:interpolator="@android:anim/accelerate_interpolator" 
   android:duration="Your Duration(in milisecond)"
    android:repeatCount="infinite"/>
 </set>