Finishing touches

As I said last time, I reckon there are two things left to do before I have a module that is worth testing.

First - I want to notify the user when a date is entered successfully. Now, this is not essential in the grand scheme of things, because when the whole app is complete, closing SSA will lead the user to a screen which shows the date (among other things). Whether or not I decide to retain it then, I want to have it now, just so that I know it's working when I test it!

The easiest way to do that is with what is called Toast - I imagine because when it is ready, it pops up! Toast is a kind of message that appears in a little box floating on the screen for a set duration.
Toast has three key components (or 'arguments', in this instance). The Context, being the current state of the application; the Text, being what you want your Toast to display; and the Duration, being how long to display it for.

As usual with Android's imaginative variable names, we get something like this:

Context context = getApplicationContext();

        CharSequence text = "You are getting married on " + WedDate + "!";

        int duration = Toast.LENGTH_LONG;

        Toast toast = Toast.makeText(context, text, duration);

        toast.show();

As you can see, here we will tell people "You are getting married on []!", for a duration of Toast.LENGTH_LONG. I don't know exactly how long that is, but it's a few seconds; certainly long enough to read this message.

Alright, so on to the second thing I wanted to add - and this is probably entirely temporary: a message on WLA to confirm that the app knows the user's wedding date.
I've put exactly the same Toast, just replacing "You are getting married on " with "Your wedding date is ", so that if I close SSA and get back to WLA at the same time as a Toast appears, I will know which Activity is responsible for it.

In both these cases, I already had the import statement - import android.widget.Toast - otherwise I would have to add it before Eclipse would be happy.

Now, bearing in mind that 1) This is one small corner of the planned app, and 2) That it may not even begin to work when tested - it's time to start testing this thing, and see what breaks!

Android Theory

I've been delving around in Android and Java help materials - tutorials, guides and forums - to help me put together this part of the app.

So, here's the first thing that I've found out, from the official guide to developing for Android here:

An activity represents a single screen with a user interface.

That means I don't want WeddingLogisticsActivity to be a big thing - I want to deal with something called, I don't know, SplashScreenActivity (now referred to as SSA) which is aimed purely at this initial screen of the app.
[Note for future reference - I will probably want a test so that SSA only runs the first time you open the app. Easiest thing that occurs to me is to check whether the variable WeddingDate is empty; if it is, run SSA, otherwise don't. That should avoid problems.]

Looking in more detail at this page, I think the way to proceed is to tell WLA to start an activity called SSA, in the terms

Intent intent = new Intent(this, SignInActivity.class);
startActivity(intent);

Or in my case:

        Intent intent = new Intent(this, SplashScreenActivity.class); 

        startActivity(intent);

Then I set up the beginnings of the new Activity for SSA in the same way; only to realise that I need to put SSA in its own file, called (logically enough) SplashScreenActivity.java as otherwise the app would get confused.
Now, I'm still seeing an error in WLA on the line Intent intent etc, as the app doesn't seem to recognise it; so I tried adding an import statement as below:

import android.content.Intent;

which solved the problem.
Import statements are my friend.

Right, in the classic way of things, it is past time to post this, and I still haven't solved the original problem. Tomorrow, I promise!

Code: Import, Activity, Extend

This next bit is focussed in the source-code folder (src), in a section named WeddingLogisticActivity.java

Eclipse has automatically added in what you see on the left here.

First of all we have the name of the package, which will eventually uniquely identify Wedding Logistics on Google Play.

Then we have the import statements. One analogy for these is academic references - if you write an essay which doesn't show the sources for your statements of fact then your readers will think you're making it up. Well, think of your app as a very sceptical reader - unless every statement is ultimately backed up in a reference [unless every method is in an imported library], it won't believe you [won't be able to execute that method].

The import statements I have already just cover me for the basic operation of the Android Operating System, and for the initial Activity that I'll get to in a moment, so I'll be adding a few, to deal with the Context (the situation on your Android), the View (what's on screen), an OnClickListener (to notice when, say, the user clicks on a button), deal with Buttons, Toast (messages that appear temporarily on screen. So called because they pop-up, I think), and a DatePicker, &c.

I've got the outline of my list from the excellent hackaday.com Android Tutorial and then added one for the DatePicker. Eclipse helpfully highlights all of the import statements I'm not using at the moment

(see the little row of symbols on the left?) so I can remove any unnecessary imports once the code is finished. Equally, as I expand the app, I'm likely to need to add more imports to cover new features.

Then we declare a public class called WeddingLogisticsActivity (henceforth abbreviated to WLA), and that it extends the core Activity.

Just to unpack that a bit - public means that other processes can refer to WLA; class - well, for a full definition of that I'll give you the wikipedia article, but the short version is that it means I could have several examples of WLA, based on the definition of it given here.

As to the bit about extending Activity, well, the Activity is a core Android class which handles some basic stuff for me - saying WLA extends Activity is a way of telling the system I want WLA to start with all the attributes of Activity, and then I want to give it some more.

At present, all WLA does which is apparent to the user is load the screen from last time; however, if the user attempts to enter the date, nothing will happen. If they click Done, nothing will happen. Unfortunately, I'm out of time, so I'll get to rectifying that next time!