Android development basicsIntroduction,Structure,Development

Boncho Valkov.Net Developer

Table of Contents

1. About Android and why to use it2. What knowledge do you need to start

Basics of programming,OOP,Databases

3. What software (IDEs) do you need Android Studio/Eclipse Emulator – Genymotion or other

4. Structure of Android app5. Main components – Intent,Activity,Service,Content

Provider,Broadcast Receiver6. Activities lifecycle 2

Table of Contents

7. Debugging and logging8. Intents, passing data between activities9. Views. Layout Management10.Listviews and Adapters11.Notifications12.HTTP Networking. AsyncTasks and Callbacks13.Local Storage – SQLLite and SharedPrefs. Content Provider.

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About Android and why to use it

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Android is a mobile operating system (OS) based on the Linux kernel and currently developed by Google.

Started back in 2008, today is the most popular mobile OS with 1.5 million daily activations, 1 billion devices in total (as of April 2013).

About Android

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About Android - Architecture

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The most popular mobile OS Large community Extremely well documented APIs Reuse existing knowledge in Java development Uses MVC

Why android

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Basics of programming in some object oriented language like C#, Java or other

OOP principals Databases – SQL/MYSQL or other XML

What do you have to know to start

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1. For programming Android studio – for a couple of months there is

official version Eclipse plus SDK tools

2. Emulator Genymotion Integrated emulator in android studio Test on actual device

What software (IDEs) do you need

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Select API Level Using Packages like JAVA Java folder Res folder Android Manifest file Gradle

Structure of Android project

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Main components

Activity Intent Service Content Provider -------------------- Broadcast Receivers Fragments Views

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Represents a single screen with an user interface plus code that runs behind it

If we have multiple activities – one must be selected as the app’s main activity.

The main activity is similar to the main() function in Java and C#

Activity

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Objects carrying messages from one component to another (within the application or outside it).

Two types of intents: • Explicit intents – tell exactly what do

you want to start to get some result• Implicit intents – tell that you what

some result, without specifying how

Intent

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Runs in the background to perform long- running operations. Doesn’t need to interact with the user.

Service

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Supplies data from one application to others on request.

- Can use different ways to store data (database, files, over a network).

Content Providers

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Respond to broadcast messages from other applications or from the system itself (called events or intents).

Applications can also initiate broadcasts to let other applications know that some data has been downloaded or processed.

Broadcast Receivers

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Kind of sub-activity Can be placed in an Activity to achieve more modular design.

-You can add or remove fragments in an activity while the activity is running.

Fragments

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Layouts Widgets

Menu Drawer Tabs

Can be created via: -XML files Programmatically

Views

Activity Lifecycle

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onCreate onStart onResume – application is running onPause onStop onDestroy

Activity Lifecycle

Demo

Debugging and logging

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F8 – step forward F9 – go next breakpoint Log.v() -VERBOSE Log.d() -DEBUG Log.i() -INFO Log.w() -WARN Log.e() -ERROR

Debugging and logging

Demo

Intents, passing data between activities

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Intents

What is an intent messages you can pass between your app components

can also send them to components in other apps, and execute a task like playing music, sending email and taking pictures.

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With an Intent you can Start activities Start services Deliver broadcasts Pass data

Intents

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Types of intents Implicit

have not specified a component they must include enough information for the system to determine

which of the available components is best to run for that intent.

Intents

Intent intent = new Intent (Intent.ACTION_VIEW, Uri.parse("http://www.softuni.bg ")); startActivity(intent);

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Intents

Implicit

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Types of intents Explicit

have specified a component, which provides the exact class to be run

usually is used for starting internal activities

Intents

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

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Put the data in the intent

Retrieve the data from the intent from the component that has been started, usually in onCreate method

Serializable objects can be passed

Passing data between activities

Intent intent = getIntent();String passedData = intent.getExtra(“data”);

Intent intent = new Intent (this,SecondActivity.class);intent.putExtra("data","i have been passed"); startActivity(intent);

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We use the intent filters to deny or allow intents to reach our app’s components.

Restrict access

Intent Filters

<activity android:exported = false>

<action android:name="android.intent.action.SEND"/> <data android:mimeType="text/plain"/> <category android:name="android.intent.category.DEFAULT"/>

Demo

Views. Layout Management

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Views. Layout Management Mandatory view props

android:layout_width android:layout_height

Match parent Fill parent Wrap Content

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Single direction, vertically or horizontally Specified by the android:orientation attribute All children are stacked one after another Can use gravity

Linear Layout

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Displays child views in relative positions The position of each view can be specified as relative to sibling

elements Can align two elements by right border

Relative Layout

Demo

List Views and Adapters

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Parts of the ListView: Rows Adapter -bridge between a

view and the underlying data for that view. Provides access to the data items.

Fast Scrolling Section Index

List Views and Adapters

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List Views and Adapters

Types of list views and adapters

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Simple List View<ListView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:id="@+id/listView"

android:layout_alignParentTop="true"

android:layout_centerHorizontal="true" />

Create ArrayAdapter

Set Adapter to the listView

Set OnClickListener

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Most of the time we need something specific

Create custom row Create Custom Adapter that extents

BaseAdapter Implement required methods

Custom List View Adapter

convertView = LayoutInflater.from(context)

.inflate(R.layout.university_row,parent,false);

Demo

Notifications

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Three required components Icon Content title Content text

Optional components Action attached to notification, usually an Activity, it’s done by

Pending Intent, by calling set Content Intent

Notifications Components

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Notification sample

NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this)

.setSmallIcon(R.drawable.notification_icon)

.setContentTitle("My notification")

.setContentText("Hello World!");

If want to add action to Notification Create Intent Create PendingIntent, by PendingIntent.getActivity Use setContentIntent to attach the pending Intent

DemoAlong with the live demo

HTTP Networking. AsyncTasks and Callbacks

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Http

Hypertext Transfer Protocol (HTTP) HTTP is the foundation of data

communication for the World Wide Web.

Needs permmitions

HttpClient defaultHttpClient = new DefaultHttpClient(new BasicHttpParams());

HttpPost httpPost = new HttpPost(path);

HttpResponse response = defaultHttpClient.execute(httpPost);

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Class that that is being executed on a different thread Prevent using the Main thread (UI) for time taking operations Extend class with AsyncTask<String,Void,String>

AsyncTask

Demo

Local Storage – SQLLite and SharedPrefs. Content Provider.

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Manage access to a structured set of data Encapsulate the data, and provide mechanisms for defining data

security The standard interface that connects data in one process with

code running in another process.

Content Providers

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Software library that implements a self-contained, zero-configuration, transactional SQL database engine.

The most widely deployed SQL database engine in the world.

Useful tools and queries: - DB Browser for SQLite Create, Select,

Delete, Update

SQLite

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Shared Preferences Store private primitive data in key-value pairs.

Local storage

SharedPreferences sp = getSharedPreferences(PREFS, Context.MODE_PRIVATE);

Editor editor = sp.edit();

editor.putString("key", "value");

editor.commit();

if (sp.contains(Name))

name.setText(sp.getString(Name, ""));

Demo

Questions?