Prasham Trivedi

Supercharge your Android Application-1(The List).

November 17, 2014

4 minutes to read.

Developing android applications are lot easy if you exactly know which platform you are developing for. But for either one or other reasons we don’t have time to leverage functionalities of our platforms to make our life easy. And as far as I can acknowledge it happens frequently with android. Breaking habits of traditional development (of web and of iOS) android has lot more bells and whistles that many of us don’t know. Here, with this series, I am not talking about animations or anything fancy. I am talking about some bricks and mortar which should be applied properly at the foundations.

The apps many of us develop are having either some complex functionalities, or having some iOS functionalities which have easy replacements, but they are generally not acceptable because they do not belong to iOS. And above all the people who decide the timeline always overestimate our power (feel free to imagine angry lord vader here). Thus we are always in rush, without having time or knowledge of some awesome things that can make our life easy. Some of us who regularly see some top android developers’ blog and/or Google+ profiles may be familiar with some or all of the tricks. But some are still learning and looking to solve their problems. If you are in the former, and have some new tricks, please share it with us. If you are later and looking for help, these are the droids you are looking for.

Before I start let me tell you one last thing, When I was building Wish ‘N U as a demo of what I have been learning, I didn’t know many of the tricks I am going to share with you, and as a result the app released on November 2013 was a laggy, slow and bit of unreliable. Fast forward to a year and I have managed to release the same app being fast, more (~70%) reliable and somehow looking beautiful. Having applied many of the tricks during development you will face many of the examples and codes related to the app.

Not talking too much let’s start with our first trick.

1.When list is used, always use ListFragment.

Fragments are awesome things to use. Learning and mastering it is bit tricky, but when you get the mastery, you will feel proud. And one of the fragment I always tend to use is ListFragment. And I recommend you to choose ListFragment over normal ListViews, because it comes with a unique functionality: Untill you set an adapter to it, it will always show default progressbar. Thus you don’t have to care about showing ProgressBar or ProgressDialog everytime you are loading a list.

It helps in numerous cases, when you are getting some data from remote server, loading local contacts or doing complex calculation before showing it on list. It takes time, and in normal case, either we show a progress dialog with Please wait or we use framelayout to show an inline progressbar with manually hide and unhide progressbars and list as per our needs.

If you use ListFragment instead of normal list view, you don’t have to manage progressbars on your own, List fragment does it for you.

	AsyncTask<Params, Progress, Result> task = new AsyncTask<Params, Progress, Result>() {
		@Override
		protected Result doInBackground(Params... params) {
			//DO YOUR BACKGROUND WORK HERE
		}

		@Override
		protected void onPostExecute(Result model) {
			super.onPostExecute(models);
			adapter = new Adapter();
			setListAdapter(adapter);
		}
}

That saves your time and thinking about showing progress because it’s handled automatically. But there are two problems we need to solve before we completely trust this approach.

The first problem we face is that we can not show numerical progress with this approach. Many of us are asked to show the actual progress of how much data (in percentage or in numbers) is downloaded, either by numbers or by progressbar. If this is strictly your requirement, this approach won’t work for you. On the other hand, showing loading indicator is only thing we needed, we should go with this approach.

Other Problem with this approach is that ListFragments only handle textual empty states. And for fanciness we are used to inflate a layout with a ListView and a view with id @android:id/empty so we can load our fancy emptyviews there. Or We do have some more controls on our layout that operates on the list. Like Spinner or SearchView for filtering the list.

It’s recommended to use ActionItems or Menus for such operations. If your list does not have action in empty view, you can easily solve this problem with help of spannables. If your list view is empty, you can show a message, and an image with it. And this message can ask your users to perform an action. Like in my case I am showing an empty message with image, which asks my users to perform refresh action which is always present in ActionBar. Here is the code to generate the spannable String.

public static SpannableString getEmptyMessage(Resources resources, String message, int color) {
	String string = new StringBuilder().append(" ").append("\n").append("\n").append(message).toString();
	SpannableString ss = new SpannableString(string);
	Drawable icon = resources.getDrawable(R.drawable.ic_launcher);
	icon.setBounds(0, 0, icon.getIntrinsicWidth(), icon.getIntrinsicHeight());

	ImageSpan span = new ImageSpan(icon, DynamicDrawableSpan.ALIGN_BOTTOM);

	ForegroundColorSpan colorSPan = new ForegroundColorSpan(color);

	ss.setSpan(span, 0, 1, Spanned.SPAN_INCLUSIVE_EXCLUSIVE);

	ss.setSpan(colorSPan, 0, string.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

	AbsoluteSizeSpan sizeSpan = new AbsoluteSizeSpan(18,true);

	ss.setSpan(sizeSpan, 0, string.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

	return ss;
}

And this return values can be easily applied by following code.

	SpannableString ss = getEmptyMessage(getResources(), message, color);
	setEmptyText(ss);

We have one more trick regarding to listview, which will be covered in next part of the series. Where we will discuss more about fragments.

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