Activity启动退出效果

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<scale
android:duration="400"
android:fromXScale="2.0"
android:fromYScale="2.0"
android:pivotX="50%p"
android:pivotY="50%p"
android:toXScale="1.0"
android:toYScale="1.0" />
<alpha
android:duration="400"
android:fromAlpha="0"
android:toAlpha="1.0" />
</set>

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android">
<scale
android:duration="400"
android:fromXScale="1.0"
android:fromYScale="1.0"
android:pivotX="50%p"
android:pivotY="50%p"
android:toXScale="0.5"
android:toYScale="0.5" />
<alpha
android:duration="400"
android:fromAlpha="1.0"
android:toAlpha="0" />
</set>

private void toMainActivity() {
if (isIn) {
return;
}
Intent intent = new Intent(this, MainActivity.class);
startActivity(intent);
overridePendingTransition(R.anim.screen_zoom_in, R.anim.screen_zoom_out);
finish();
isIn = true;
}