How to perform a fade animation on Activity transition?

Question

I am codifiying a transition effect between my logo activity and my Main activity, but I have the problem that before vanish the activity move to top:

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

    <alpha
        android:duration="2000"
        android:fromAlpha="0.0"
        android:toAlpha="1.0" >
    </alpha>

</set>

How could I improve this code to get only a vanish effect?

Answer 1

You could create your own .xml animation files to fade in a new Activity and fade out the current Activity:

fade_in.xml

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
           android:interpolator="@android:anim/accelerate_interpolator"
           android:fromAlpha="0.0" android:toAlpha="1.0"
           android:duration="500" />

fade_out.xml

<?xml version="1.0" encoding="utf-8"?>
<alpha xmlns:android="http://schemas.android.com/apk/res/android"
           android:interpolator="@android:anim/accelerate_interpolator"
           android:fromAlpha="1.0" android:toAlpha="0.0"
           android:fillAfter="true"
           android:duration="500" />

Use it in code like that: (Inside your Activity)

Intent i = new Intent(this, NewlyStartedActivity.class);
startActivity(i);
overridePendingTransition(R.anim.fade_in, R.anim.fade_out);

The above code will fade out the currently active Activity and fade in the newly started Activity resulting in a smooth transition.

UPDATE: @Dan J pointed out that using the built in Android animations improves performance, which I indeed found to be the case after doing some testing. If you prefer working with the built in animations, use:

overridePendingTransition(android.R.anim.fade_in, android.R.anim.fade_out);

Notice me referencing android.R instead of R to access the resource id.

UPDATE: It is now common practice to perform transitions using the Transition class introduced in API level 19.