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En provenance du cours de CentraleSupélec

Build Your First Android App (Project-Centered Course)

599 notes

CentraleSupélec

Build Your First Android App (Project-Centered Course)

599 notes

What you’ll achieve: In this project-centered course*, you’ll design, build, and distribute your own unique application for the Android mobile platform. We’ll provide you with a set of customizable building blocks that you can assemble to create many different types of apps, and that will help you become familiar with many important specificities of Android development. When you complete the project, in addition to having a personalized app that you can use and share, you’ll have the skills and background you need to move on to more advanced coursework in Android development. What you’ll need to get started: This project-centered course is designed for learners who have some prior experience programming in Java, such as an introductory college course or Coursera’s Java Programming Specialization (https://www.coursera.org/specializations/java-programming). You will need a computer with a stable Internet connection, but you will not need an Android phone - we’ll use free software that you can use to emulate a phone on your computer. We'll use Android Studio as IDE; it is compatible with most computer and operating systems. You can find detailed system requirements here: https://developer.android.com/sdk/index.html#Requirements. *About Project-Centered Courses: Project-centered courses are designed to help you complete a personally meaningful real-world project, with your instructor and a community of learners with similar goals providing guidance and suggestions along the way. By actively applying new concepts as you learn, you’ll master the course content more efficiently; you’ll also get a head start on using the skills you gain to make positive changes in your life and career. When you complete the course, you’ll have a finished project that you’ll be proud to use and share. Time: 10 hours of study, 10 hours of active project work

À partir de la leçon

Create the Storyboard for Your Application

In this module you will design your personalized app from a user's perspective. We will show you elements you can combine in your design, and how to document it to get feedback from prospective users or to organize your thoughts. If you get stuck on the quiz or peer-reviewed assignment, you should post on the Discussion Forum to ask for help. And if you finish early, we hope you'll go there to help your fellow classmates as well. To get started, please jump into the first lesson below!

Some components of the graphical user interface3:55

Layout: organize the views on your screens5:24

Add actions5:24

Rencontrer les enseignants

Dr. Virginie Galtier
Associate Professor
Computer Science
Michel Ianotto
Associate Professor
Computer Science

In the second part of the presentation you've learned that views are organized

on the screen according to a layout.

Layouts are views themselves, which allows them to be nested within another layout.

It's possible to position views in relation to one another,

provided that each view is given a unique identifier.

So this allows for a nice graphical user interface, but it lacks interactivity.

And what about interactivity?

We need to do something about that.

So we're going to work on that right away.

The other side of the activity board is black, because the user will not see this side.

But on this side, we're going to stick another set of magnets

to control the white side, the displayed screen.

There is quite a range of actions, that we can specify for

when the OK button is clicked, for instance.

And there are multiple events we can react to

in addition to the click on the OK button.

So, let's see some of these controls.

First, I can change the appearance of the button.

Like its background color, for instance.

When the event 'button_OK is clicked' appears,

then I'll do the following action:

I'll set the background color of this view to the value 'blue'.

So the button is clicked, and, it turns blue.

Or I can make it invisible. The event is still the same, the OK button is

clicked, but now the action is to change the visibility of the OK button.

Knowing the ID of an editText can also allow me to retrieve

the text typed in into it by the user.

So for instance here, when this button is clicked, my first action

is to retrieve the text stored in the view EditText_op1.

That is this view.

So here let's say that the user entered 3, I retrieve this value and

I store it into the variable called nb1.

Next my second action is to retrieve the text typed in the second EditText,

EditText_op2.

Let's say the user enters 4, so now the variable nb2 = 4,

and my last action is to set the text displayed in this TextView here,

TextView_result, to be the value nb1 + nb2.

So here I'll display the String "7".

So we already have a very simple functional calculator,

but maybe you have something more ambitious in mind,

something which would be more natural to achieve using multiple activities.

Well Android enables you to define as many activities and

screens as you like for an application.

And just as for views, each activity or screen is given a unique identifier.

But at a given time of the execution of your application,

only one activity is fully active.

And this activity presents a screen to the user,

and the user cannot interact with any other activity.

So of course,

an action associated with this interface can be to change the activity.

Like here, when the OK button is clicked, my action is to change

activity to start a new activity, an activity named act_items.

So the user clicks, and here I have my new activity.

The screen associated with the new activity comes into the foreground,

and the user no longer interacts with the first activity, which is stopped.

If the user clicks the back button on the phone, the current activity is destroyed,

and the screen of the previous activity, which was stopped,

is brought to the foreground again.

When you move from one activity to the next, you can pass some information along.

For instance, in the first activity I retrieve the age of the user,

and I start the second activity, named activity act_howTo.

And I can provide the value of the variable 'age' to this new activity.

And open starting, the other activity can retrieve this value,

and put it into a variable and then use it afterward.

For instance here you can display a customized message.

You can design plenty of Android applications as sets of activities and

associated graphical user interfaces.

In the next series of readings you will discover additional widgets,

actions and events.

And then you will be able to imagine something fun or

useful to make our user happy.

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