ExpandableTextView.java 文件源码

@TargetApi(Build.VERSION_CODES.HONEYCOMB)
private static void applyAlphaAnimation(View view, float alpha) {
    if (isPostHoneycomb()) {
        view.setAlpha(alpha);
    } else {
        AlphaAnimation alphaAnimation = new AlphaAnimation(alpha, alpha);
        // make it instant
        alphaAnimation.setDuration(0);
        alphaAnimation.setFillAfter(true);
        view.startAnimation(alphaAnimation);
    }
}