Android Step by Step

8/3/2019 Android Step by Step

1/22

1

BuildingBuildingHelloWorldHelloWorld

Android ApplicationAndroid Application

Step by Step.Step by Step.

Sang ShinSang ShinMichle GarocheMichle Garoche

www.javapassion.comwww.javapassion.comLearn with Passion!Learn with Passion!


2/22

2

Disclaimer

Portions of this presentation are modificationsbased on work created and shared by theAndroid Open Source Project

> http://code.google.com/policies.html

They are used according to terms described inthe Creative Commons 2.5 Attribution License

> http://creativecommons.org/licenses/by/2.5/


3/22

3

Goals of This Presentation

Get you started with Android applicationdevelopment

Get you know the development environment

>

Will focus on Eclipse-based Android developmentenvironment (instead of command-line-basedone)

Get you be exposed to the basic building blocksof an Android application in a cursory manner

> The details will be covered in the rest of thecourse


4/22

4

Topics

Installation and configuration

Building blocks of Android application

> Activities

>

Layout resource files> AndroidManifest.xml

> Resource files - strings.xml

> R.java


5/22

5

Installation &Installation &

ConfigurationConfiguration


6/22

6

Software Needed

JDK (Java Development Kit)

> Android application is Java application

Eclipse IDE>

Editor, Debugger, profiler, deployment Android SDK

> Libraries, samples, documentation, handsetemulators, debugger, command line tools

Eclipse ADT (Android Development Tools) plug-in

> Give you a powerful, integrated develpmentenvironment


7/227

Creating Android Project using Eclipse

Automatic creationbuilding blocks of anAndroid application

> Starting Activity

class> Layout resource file

> AndroidManifest.xml

> strings.xml

> R.java> Android library


8/228

Building Blocks ofBuilding Blocks of

Android ApplicationAndroid Application


9/229

Building Blocks of Android Application

Activity classes

Layout resource files

Resource files>

strings.xml AndroidManifest.xml

R.java (automatically created from resourcefiles)

Android library (automatically configured)


10/2210

Building Blocks of Android Application


11/2211

Activity Class

Each Activity class typically represents a screen

> Like a JSP page in a Web application

The onCreate() method of Activity class getscalled by the Android system when yourActivity starts> You create your UI inside the onCreate() method

Every Activity has to be described in theAndroidManifest.xml file

An Activity is typically chosen as a starting oneof your application - like a class that has amain() method in Java

> Special configuration in AndroidManifest.xml


12/2212

Activity Class Example

package com.javapassion;

import android.app.Activity;import android.os.Bundle;

publicclass HelloWorldActivity extends Activity {

/** Called when the activity is first created. */ @Override publicvoid onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);

//Create UI using Layout resource filesetContentView(R.layout.main);

}}


13/22

13

Layout Resource Files

Every screen has a corresponding layoutresource file> Unless you create UI programmatically

Each activity class specifies which layoutresource file to use for each screen itrepresents

> Using setContentView(R.layout.main);

Are located under /res/layoutdirectory


14/22

14

Layout Resource File Example


15/22

15

Resource Files - strings.xml

Let you define the text strings of yourapplications in a well-known file> Rather than in Java code

> Rather than in Layout resource files

The strings are then referred to through thenames assigned to them

> The mapping is done through R.java

Located under /res/values directory


16/22


17/22

17

AndroidManifest.xml file

Every application must have a manifest filecalled AndroidManifest.xml file (with preciselythat name) in its root directory.

The manifest presents essential information

about the application to the Android system,information the system must have before it canrun any of the application's code.


18/22

18

Info. in AndroidManifest.xml file

Java package for the application.> The package name serves as a unique identifier for

the application.

Activities

> One activity is designated as a starting Activity


19/22

19

AndroidManifest.xml


20/22

20

R.java

Automatically created by Android system for allresources defined


21/22

21

R.java


22/22

22

Thank you!Thank you!

Sang ShinSang ShinMichle GarocheMichle Garoche

www.javapassion.comwww.javapassion.comLearn with Passion!Learn with Passion!

Android Step by Step

Documents

Transcript of Android Step by Step