android session-1-sajib
DESCRIPTION
TRANSCRIPT
Android Training
Session - 1
Presented By: A.T.M. Hassan Uzzaman
Agendas
• Introduction to Android• Application Structure• Layouts & Drawable Resources• Activities and Activity lifecycle• First sample Application• Launching emulator
Introduction A Linux based Operating System designed primarily for
touch screen mobile devices Initially developed by Android Inc and later purchased by Google in 2005 The first Android powered device was sold in Oct 2008 Android is Open Source and Google releases code under
Apache2 license Google Play Store
Brief History – Android
2009
SDK 1.5 (Cupcake) New soft keyboard with “autocomplete” feature
SDK 1.6 (Donut) Support Wide VGA
SDK 2.0/2.0.1/2.1 (Eclair) Revamped UI, browser
2010
SDK 2.2 (Froyo) Flash support, tethering
SDK 2.3 (Gingerbread) UI update, system-wide copy-paste
5
2011– SDK 3.0/3.1/3.2 (Honeycomb) for tablets onlyNew UI for tablets, support multi-core processors– SDK 4.0/4.0.1/4.0.2/4.0.3 (Ice Cream Sandwich)Changes to the UI, Voice input, NFC
2012 SDK 4.1/4.1.1/4.2(Jelly Bean) Performance optimization, refined UI
HoneycombAndroid 3.0-3.2
Ice cream SandwichAndroid 4.0+
Jelly Bean 4.1+
6
API Level
Platform Version API Level Version Name
Android 4.2 17 Jelly bean
Android 4.1, 4.1.1 16 Jelly bean
Android 4.0.3, 4.0.4 15 Ice cream sandwich
Android 4.0, 4.0.1, 4.0.2 14 Ice cream sandwich
Android 3.2 13 Honey Comb
Android 3.1.x 12 Honey Comb
Android 3.0.x 11 Honey Comb
Android 2.3.4Android 2.3.3
10 Gingerbread
7
API Level
Platform Version API Level Version Name
Android 2.3.2Android 2.3.1Android 2.3
9 Gingerbread
Android 2.2.x 8 Froyo
Android 2.1.x 7 Eclair
Android 2.0.1 6 Eclair
Android 2.0 5 Eclair
Android 1.6 4 Donut
Android 1.5 3 Cupcake
Levels
Activity BackStack
• Main activity calls activity2
Activity 2Push Operation(Last in)
Activity 2 is visible on screenMain activity goes in background
backstack
main
Activity BackStack
• From activity2, user presses back button
Activity 2
Main activity is visible on screen and activity 2 is destroyed
backstack
main
Pop operation (First Out)
Java Source Code
Java Byte Code
JVM
Java Byte Code
Dalvik Byte Code
Java Compiler
DexCompiler
Dalvik Executable
DVM
Dalvik Virtual Machine
Vs Java Virtual
Machine
Differences between DVM and JVM
Machine
Property
DVM JVM
Architecture base
Register Stack
No of operations
fewer more
File format .dex .class
JVM - Stack Based
POP 20 POP 7 ADD 20, 7, result PUSH result
DVM - Register Based
Add R3,R1,R2
15
Android Java Consists of
Android Java =
Java SE - AWT/Swing+
Android API
APK file format: Application package file Zip package format based on JAR file format Apk holds
Code(.dex file) Resources Assets Certificates Manifest file
Once .apk is installed on a device: Own security sandbox A unique Linux UserID Own Virtual Machine Own Linux process
Application Fundamentals
Android Application Components
• Activities: An Activity is an application component that provides a screen with which users can interact in order to do something.
• Services: A Service is an application component that can perform long-running operations in the background and does not provide a user interface.
• Content Providers: A content provider manages a shared set of application data.
• Broadcast Receivers: A broadcast receiver is a component that responds to system-wide broadcast announcements.
Activity Lifecycle
Configuring Android Development
Environment
Requirements
JDK 6 (Java Development Kit ) and above– (JRE alone is not sufficient)– http://www.oracle.com/technetwork/java/javase/downloads/index.html
Eclipse IDE– Eclipse + ADT plugin– Android SDK Tools– Android Platform-tools– The latest Android platform– The latest Android system image for the emulator
• http://developer.android.com/sdk/index.html
Other development environments• Apache Ant 1.8 or later ( http://ant.apache.org/ )• Not compatible with Gnu Compiler for Java (gcj)
Note: Some Linux distributions may Include JDK 1.4 or Gnu Compiler for Java, both of which are not supported for Android development.
Adding Platforms
and Packages
Figure . The Android SDK Manager shows the SDK packages that are available, already installed, or for which an update is available.
Sample Application
Understanding Android Project Structure
• AndroidManifest.xml– The manifest file describes the fundamental characteristics of the app and
defines each of its components.
• src/– Directory for your app's main source files. By default, it includes an Activity
class that runs when your app is launched using the app icon.
• res/– Contains several sub-directories for app resources. Here are just a few:
– drawable-hdpi/• Directory for drawable objects (such as bitmaps) that are designed for high-
density (hdpi) screens. Other drawable directories contain assets designed for other screen densities.
– layout/• Directory for files that define your app's user interface.
– values/• Directory for other various XML files that contain a collection of resources, such as string and color definitions.
AndroidManifest.xml file
• Every application must have an AndroidManifest.xml file.
• The manifest presents essential information about the application to the Android system.
• The manifest does the following– It names the Java package for the application. The package
name serves as a unique identifier for the application.– It describes the components of the application: The activities,
services, broadcast receivers, and content providers.– It determines which processes will host application components.– It also declares the permissions that others are required to
have, in order to interact with the components of the application
– It declares the minimum level of the Android API, that the application requires.
The file R.java is an auto-generated file, that is added to your application, by the Android plug-in.
This file contains pointers into the drawable, layout, and values directories.
You should never modify this file directly. You will be only referencing R.java in most of your applications.
R.Java
package testPackage.HelloWorldText;
public final class R {public static final class attr {}
public static final class drawable{public static final int icon=0x7f020000;
}public static final class layout {
public static final int main=0x7f030000;}public static final class string {
public static final int app_name=0x7f040000;}
}
R.Java: Content
Resources
Almost all Android applications will have some sort of resources in them; at a minimum they often have the user interface layouts in the form of XML files.
• Android offers one more directory where you can keep files which also will be included is package. This directory called /assets.
•The difference between /res and /assets is that, Android does not generate IDs of assets content.
•You need to specify relative path and name, for files inside /assets.
InputStream is = getAssets().open("text.txt");
Code to Access Assets :
References
www.developer.android.com
www.developer.android.com/sdk/index.html
Questions ?
Thank You.