Android basics

Android Programming

Workshop in University College Ghent
Ismo Harjunmaa

Content of the Workshop:
1. How android programming differs from plain
Java programming
2. Tools for developers
3. Making Hello World
4. Making simple game
5. Deploying application to Android device
6. Publishing application in Adnroid Marketplace

2
Ismo Harjunmaa – Workshop Gent 9.2.2012

Folder structure of Android project
 .java Source files are in src-folder
 R.java resource class in gen-folder
 Fonts etc. in assets-folder
 Project specific resources res-folder
 Graphic files in drawable-folders
 Vertical UI layout in layout-folder
 User-interface texts, tables, styles
and colors in values-folder
3

Activity-class
 The core of your application
 All the event handlers are implemented in this
class (these classes)

4

UI layout in XML-file
 By default main.xml file is created in folder
res/layout
 All the User Interface elements are described in
XML-file
 Root element is the layout and there is eight
different ones to pick from

5

Designing UI layout
 UI is designed in
Eclipse either in
graphical layout
view or writing
elements with
attributes to
main.xml
 Elements are placed
by dragging them
from library
6

Description file AndroidManifest.xml
 The most important description file
AndroidManifest.xml is created in the root
folder of your project
 In this file you can specify level of the API,
screen resolution support, testing methods,
permissions etc.
 Eclipse shows the attributes of the file either in
plain text or selection fields

7

Java programming

8

DDMS (Dalvik Debug Monitor Server)
 Perspective in Eclipse that shows all running
emulators or device
 Inside this perspective is a view where you can
emulate incoming call, SMS or GPS-signal
 In this perspective you can browse the folder
structure of the emulator or device

9

Android-SDK command-line tools
 All of the tools that Eclipse uses are actually in
the Android-SDK as command-line tools
 One command-line tool is NOT in Eclipse: adb
(Android Debug Bridge)
 With adb you can list processes, connect to
SQLite databases etc.

10

Tools for developers: LogCat
 Developer needs to know bit more what is the
state of the application
 Under folder android-sdk/platform-tools is the
adb command
 Adb logcat shows the logs that device has output

11

Tools for developers: LogCat
 In the code you use logs like this:

import android.util.Log;

private static final String TAG =
HelloWorldActivity.class.getSimpleName();
Log.d(TAG, ”This is DEBUG level msg”);
Log.e(TAG, ”This is ERROR level msg”);
12

Tools for developers: traceview
 Writes full log from all events into SD-card
 Remember to choose SD-card size when creating
the AVD
 Application needs permission to write external
file
 Permissions are given in the applications
AndroidManifest.xml -file
 After the trace file is commited traceview is the
tool to analyze the trace file
13

Tools for developers: draw9patch
 Application windows have frames which consists
nine pieces: upper-left corner, top... etc.
 So called patch dividing tool is installed with
Android SDK
 Before using the tool you have to draw button,
window or frame in drawing tool like photoshop
 Go to Androidsdk/tools folder and open
draw9patch

14

Tools for developers: zipalign
 If you are NOT using Eclipses ADT Plug-in, you
have to run zipalign tool which compacts the
APK-package

15

Tools for developers: sqlite3
 In the android-SDK package there is SQLite3
database ready-to-use
public class DatabaseHelper extends SQLiteOpenHelper {
private static String DATABASE_NAME = "SensorGame";
private static int DATABASE_VERSION = 3;

public DatabaseHelper(Context context, String name,
CursorFactory factory,int version) {
super(context, DATABASE_NAME, null,
DATABASE_VERSION);
}
...
16

Java programming

17

Making Hello World
 Open Eclipse
 Choose from menu:
File > New... > Android Project
 Choose Build Target from option list:
Android 3.X Android Open Source Project
 Open main.xml from folder res/layout
 While on Graphical Layout view drag
TextView-element on the layout and set text
18

Media player
 Found in package android.media
 Can play music or video
 Played resources are positioned in res/raw folder
 Common methods are available
playing: play()
pausing: pause()
stopping: stop()

19

Sensors in Android Device
 From version 1.6: Light, Proximity, Temperature,
Pressure, Gyroscope, Accelerometer, Magnetic
field, Orientation
 From version 2.3: Gravity, Linear acceleration,
Rotation vector, Near Field Communication
 Not all of them are in your device
 SensorManager is the class which controls the
sensors

20

Making simple game
 Create another Android project:
File > New... > Android Project
 Drag three textViews and three seekBars onto
the main.xml
 Give names for views and bars like XView, XBar,
YView, YBar... so you can reference them


21

Making simple game
 In this example we are using Acceleration sensor
 Use the SensorManager to create the
acceleration sensor
 For using sensor you have to first register the
sensor and on leave unregister

22

References
 Komatinemi, MacLean & Hashimi: Pro Android 3

Android basics

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