Useful tools for an effcient development of an Android App - The Android SDK

Transcription

1 RWTH Aachen University Chair of Data Management and Data Exploration Prof. Dr. T. Seidl Proseminar Useful tools for an effcient development of an Android App - The Android SDK Marco Moscher June 2012 Supervision: Dipl.-Ing. Marwan Hassani

2 Declaration of Originality The material in this paper has not previously been submitted for a degree in any University, and to the best of my knowledge contains no material previously published or written by another person except where due to acknowledgement is made in the paper itself. Aachen, June 26, 2012

3 Contents List of Figures 3 Abstract 5 1 Introduction to Android What is Android? The Android SDK Using the Android SDK Explaining the fundamental principles Design a layout Collaborate layout and functionallity Debugging an App using SDK features DDMS in chorus with LogCat Advantages of the Android SDK features 20 Bibliography 21 A Appendix 22 A.1 Behind the scenes (Dalvik VM) B List of Abbreviations 24 C Source code listings 26 C.1 Java source code C.2 XML (layout) source code

4 List of Figures 1.1 Global market share of different mobile OS ContactAndCameraExplorer screen shots SDK-Manager [8] GUI-Designer compared to XML-Editor startactivity() Intent-Object transmitting diagram startactivityforresult() Intent-Object transmitting diagram The Eclipse standard debug perspective The Eclipse DDMS perspective LogCat-View in Eclipse A.1 Android component stack [9]

5 Abstract The following article will introduce the Android-SDK for developing Apps for the Android-OS. It will shortly mention the Android-OS, describe how to integrate the SDK in the development environment and mainly focus on the features included by the ADT-Plugin for Eclipse. Especially it will give an introduction in using the Designer and Debugger. For example it will be illustrate how to use the LogCat-Class in chourse with the Debugger for gathering information about a running App. Furthermore the collaboration between layout and functionality will be explained shortly and a introduction in the fundamental programming principles for Android with using Java is given. 5

6 Chapter 1 Introduction to Android 1.1 What is Android? Android is an operating system (OS) for mobile and hand-held systems. The Android OS was founded in the year 2003 by Andy Rubin and acquired by Google in Until now the OS is developed by the Open Handset Alliance - with Google acting as the main driver [2]. The Android OS is based on the open-source Linux-Kernel and implemented in Java, so everybody is able to contribute to its future. As being licensed under GNU GPLv2 [2] Android SDK is free of charge. Figure 1.1: Global market share of different mobile OS As seen in Figure 1.1 today Android is the leading OS on global mobile device market with 56,1% followed by Apple with the iphone-os reaching 6

7 1.1. What is Android? 7 22,6% [4]. For that reason Apps for the Android OS could reach about 100% more users in contrast to an iphone App[1].

8 Chapter 2 The Android SDK The Android SDK will be introduced and demonstrated by two tools coming with it: - Graphical-User-Interface (GUI) Designer - Dalvik-Debug-Monitor-Server (DDMS) These tools along with other important features for implementing, designing and debugging an App, such as Activities, Intents, the ADB, Emulator and LogCat will be explained using the example of a simple App called ContactAndCamera- Explorer. Figure 2.1: ContactAndCameraExplorer screen shots As shown in the figure 2.1 the App is divided in four different App regions, called Activities. On its right the App shows the possibility of accessing the contacts and with tapping on an entry, the option to edit e.g., Names and Adresses. On the left it communicates with the built-in camera and handles the bitmap-data, committed by the camera itself, of a taken photo for displaying it as a thumbnail. 8

9 2.1. Using the Android SDK Using the Android SDK In order to enable users to participate with the SDK, which includes all API (Application-Programming-Interface) for the currently known Android-Platform versions (1.1 up to 4.0.x) and platform specified compiling/linking tools, Google rolls out the Android SDK Manager. This Manager (Figure 2.2) makes it possible to install and manage the necessary tools in a simple way. Furthermore a Java- Figure 2.2: SDK-Manager [8] Development-Kit (JDK) and maybe an Integrated-Development-Environment (IDE) are needed. Over the course of this article I will use the Eclipse IDE with the Android Development Tools - Plugin (ADT) designed by Google, especially for Eclipse [5]. This plugin extends the capabilities of the IDE by providing a designer to create a GUI and a debugger to debug an App within the IDE, e.g. by using the DDMS perspective.

10 2.2. Explaining the fundamental principles Explaining the fundamental principles A typical Android App consists of classes and layouts using each other. Classes are used to implement the program logic, and create the App basic functionality. These classes use the layout to display information on the screen and to react on user interactions. Usually every class implements one layout, e.g. the ContactAndCameraExplorer consists of four class files, where each one uses a different layout file. In this case a class is called Activity. For that reason Activity often means the collaboration between a class (extending the Activity class) and a layout file. Utilizing the SDK in chorus with the ADT plugin a developer does not have to take care of compiling and linking the created layouts. The SDK-Tool aapt (Android-Asset-Packing-Tool) will automatically create the needed Java code of the layout files and merge them into one class called R. For using a layout inside a class file the R class has to be imported in the header, as shown in listing 2.1, line 3. Listing 2.1: improting the R class - MainActivity.java (l. 1-3) 1 package mm.dev. contact ; 2 3 import mm.dev. contact.r; As a consequence a layout file is only used to describe the GUI and is written in the Extensible-Markup-Language (XML), listing Design a layout As mentioned before the GUI is described with XML which uses different tagnames to identify the type of an element and a couple of predefined attributes, beginning with the prefix android:, to set the different styles. These attributes are nearly the same as the ones used in Cascading Style Sheets (CSS) for styling a HTML-Site. Listing 2.2: Contact-Example Button - main.xml (l. 8-18) 1 < Button 2 android:id ="@+id/ contactbutton " 3 android: layout_ width =" wrap_ content " 4 android:layout_height =" wrap_content " 5 android:layout_marginbottom ="40 dip " 6 android: onclick =" onchoose " 7 android:text / bt_init_contact " 8 android:textsize ="14 pt" 9 android:padding ="10 dip "

11 2.2. Explaining the fundamental principles android:background =" # ED" 11 /> Listing 2.2 is an extract of the initial Activity layout and indicates the Contact- Exmaple -Button (compare Figure 2.1). This GUI element receives an ID contactbutton, to access its information in the further program logic. Additionally e.g., a background color, a padding and an event handler (onchoose() method) for the onclick-event are described. Futhermore the SDK provides others input events such as onlongclick(), on- FocusChange() and more [7]. As demonstrated in Listing 2.2 there is the possibility to create all App layouts directly in XML (Figure 2.3, right side). Even more it is practicable in another, easier, way by using the GUI-Designer with its What-You-See-Is-What-You-Get (WYSIWYG) Editor (Figure 2.3, left side). Sometimes it can be useful comparing both methods. First drag and drop all needed elements into the layout grid with the GUI-Designer and then finally define its detailed styles in the XML file. Therefore a switch between the designer and the texteditor is always possible. Figure 2.3: GUI-Designer compared to XML-Editor To obtain functionality and interactions within the GUI, the next part presents how to set a layout as the currently window design and how to interact with the mentioned events.

12 2.2. Explaining the fundamental principles Collaborate layout and functionallity As mentioned before a class file has the ability to access a layout by importing the R-class (cf. Section 2). This class includes all defined ID s, strings, arrays and other values created within the layout, separated by its category type. R.id.button_contact (category type "id") R.layout.main (category type "layout") Each class that extends the Activity class, can easily set its GUI by using the function setcontentview(), passing the layout as parameter by using the R class. Normally this function is placed in the oncreate() method and initiates the layout, as shown in Listing 2.3. Listing 2.3: setcontentview() - MainActivity.java (l ) 1 protected void oncreate ( Bundle savedinstancestate ) { setcontentview ( R. layout. main ); 5 } To interact and switch between different GUI s which is often associated with user interaction - such as a button onclick-event - the Activity class implements methods like startactivity() and startactivityforresult(). These methods are both initializing another Activity class. public class MainActivity extends Activity { public void onchoose( final View button ) { startacivity( new Intent( this, ContactExplorerActivity.class ) );.. }... } public class ContactExplorerActivity extends ListActivity {... public void oncreate( Bundle savedinstancestate ) { }... } Figure 2.4: startactivity() Intent-Object transmitting diagram Figure 2.4 shows the onchoose() method onclick-event for both buttons in the mainlayout (compare Listing 2.2) - calling the startactivity() method for initializing a new class (ContactExplorerActivity) and furthermore another GUI.

13 2.2. Explaining the fundamental principles 13 Both - startactivity() and startactivityforresult() - methods need an Intent- Object as parameter, so that every Activity is aware of its parent class and intention of call (Intent). Therewith and by adding parameters to the Intent-Object, the framework offers the possibility to transfer information between different classes. Listing 2.4: setting Intent parameters - ContactExplorerActivity.java (l ) 1 Intent contactinformations = new Intent ( this, ContactInformationActivity. class ); 2 contactinformations. putextra (" referenceid ", position ); 3 contactinformations. putextra (" vorname ", forename ); 4 contactinformations. putextra (" nachname ", surname ); 5 6 this. startactivityforresult ( contactinformations, EDIT_CONTACT_CALL ); The transmitted Intent-Object in Listing 2.4 which communicates between the ContactExplorerActivity and ContactInformationActivity classes includes three parameters, two string-values (vorname, nachname) and an integer-value (referenceid), to transfer needed information. Accessing these parameters in the child class (ContactInformationActivity) is very easy, as shown in Listing 2.5. Listing 2.5: accessing intent parameters - ContactInformationActivity.java (l ) 1 protected void oncreate ( Bundle savedinstancestate ) { // reading data committed by partent activty - through the intent. 5 final Bundle data = getintent (). getextras (); 6 7 this. referenceid = data. getint (" referenceid "); } In case an Activity class is called with startactivityforresult() - compare figure the affected class has to signal finishing its work flow by calling the finish() method to commit the result intent. Previously, it has to create this intent object, setting its values like in Listing 2.4, and combine this with a result-status-code in the setresult() method. So furthermore the child class can signal its parent class which type of result is transmitted, by setting a significant result-status-code. Thereby the parent class has the ability to interact in a conform way with the result values. To ensure that all these information get transmitted, to indicate the point of loosing information or to eliminate mistakes, the SDK combined with the ADT

14 2.2. Explaining the fundamental principles 14 public class ContactExplorerActivity extends ListActivity { protected void onlistitemclick( ListView l, View v, int position, long id) {... Intent contactinformations = new Intent(...); this.startactivityforresult( contactinformations, EDIT CONTACT CALL); } protected void onactivityresult(int requestcode, int resultcode, Intent data) {... if( requestcode == EDIT CONTACT CALL ){ if( resultcode == Activity.RESULT OK ) { //save new contact data, transmitted by data }else{.. } } }... } public class ContactExplorerActivity extends ListActivity {... public void oncreate( Bundle savedinstancestate ) { } public void saveandclose( final View view ) {... Intent changes = new Intent(); //putting data to the result intent changes.putextra( referenceid, this.referenceid);... setresult(result OK, changes); finish(); }... } Figure 2.5: startactivityforresult() Intent-Object transmitting diagram plugin for Eclipse brings tools for debugging an App and logging information.

15 2.3. Debugging an App using SDK features Debugging an App using SDK features The SDK offers two different types of options for debugging and observing a running App to the developer. Firstly the direct debugging on a mobile device running the Android-OS and secondly the Emulator for executing an App in an emulated OS using a desktop PC. For using a real device the USB debugging option (Settings Developer options USB debugging) and the privilege to install unsigned Apps (Settings Security Unknown sources) are necessary. Otherwise to use an emulator for simulating a running device a Android- Virtual-Device (AVD) image is needed. This image can be created with AVD- Manager (Windows AVD Manager), which comes simultaneously with the SDK-Manager (cf. Section 2.1). For debugging an App within the emulator the correct AVD has to be selected in the options dialog (Run Debug Configurations.. Targets Deployment Target Selection Mode Automatic). By default, if a mobile device is connected, the IDE will use this external device. With clicking on the Bug-Button in the IDE bar the debugger will start its routine. The App gets compiled, transferred and installed on the Android device automatically. At the same time the ADB connects to the debugging server running on the device and supplies information, e.g the log trace (cf. Section 2.3.1). By default Eclipse offers a Debug perspective (Figure 2.6) for the standard debugging options. (Window Open Perspective Debug)

16 2.3. Debugging an App using SDK features 16 Figure 2.6: The Eclipse standard debug perspective

17 2.3. Debugging an App using SDK features DDMS in chorus with LogCat An even more complex debugging perspective is the DDMS, Figure 2.7. It offers some more features than the debug perspective that typically comes with Eclipse. In addition it is possible to capture screen shots, gather heap or stack information, to emulate incoming calls, SMS and to fake the current geographic position (GPS). Figure 2.7: The Eclipse DDMS perspective In chorus with the DDMS it is handy to use the SDK Log class. The Log class offers the possibility to throw an error/warning combined with a message out of the running App. These can be separated by different error-levels verbose

18 2.3. Debugging an App using SDK features 18 (lowest priority) up to silent (highest) by using the right methods. In Figure 2.8 the App throws 18 errors at debug (d()-methode d = debug) and with warning level. The LogCat tool now dumps all thrown errors into a log trace which can be recovered via the LogCat-View (Windows Show View LogCat) docked into the DDMS perspective. Figure 2.8: LogCat-View in Eclipse In the example App the Log class is used to observe either entering or leaving a method and even more it logs values getting transmitted between different activities using the Intent-Object, compare the shown Listings below. Listing 2.6: logging method calls - MainActivity.java (l ) 1 protected void oncreate ( Bundle savedinstancestate ) { 2 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering oncreate ()"); } Listing 2.7: logging transmitted values - CameraActivty.java (l.37-54) 1 requestcode, int resultcode, Intent data ) { Log. d( MainActivity. MM_ INFORMATION, this. getclass (). getsimplename () + ": " + " Entering onactivityresult ()"); 2 Log.d( MainActivity. MM_INFORMATION, " requestcode : "+ requestcode + ", resultcode : " + resultcode + " "); }

19 2.3. Debugging an App using SDK features 19 Listing 2.8: throw warings - ContactExplorerActivity.java (l ) 1 protected void onlistitemclick ( ListView l, View v, int position, long id) { if( names. length >= 2 ) { } else { 6 Log.w( MainActivity. MM_WARNING, this. getclass (). getsimplename () + ": " + " Current contact [ "+ item + " ] has no surname, splitting and accessing the array would cause an Error! "); 7 } 8 9 }

20 Chapter 3 Advantages of the Android SDK features In conclusion the Android SDK is a very powerful conjunction of tools and functions for inventing and writing Android Apps. Beginning with a simple installation using the SDK-Manger (cf. Section 2.1) along with many new perspectives and functions coming with the ADT plugin in Eclipse (cf. Section 2.2) until at least the debugging suite (cf. Section 2.3), the SDK supplies many features for a better work flow. For example the programmer does not have to manage and organize the assets or the project internal linking of files. Furthermore it offers many ready-to-run Sample-Projects (File New Project Android Android Sample Project) to become acquainted with SDK and Framework. So even for the first basic program you do not have to have any knowledge about programming Java code or knowing the Android basics - easily create it and Try & Error the App. If you are not interested in developing in an IDE, Android also bids the option to use the command-line tools which are even more inefficient [6]. At least it should be mentioned that all features include by the Android SDK and even the Eclipse IDE are open-source tools and free of any charge. This is the, in my opinion, a major point for using Android. In contrast to the famous iphone there is no need for any budget to invent an App for Android. If you are even interested in developing an iphone OS App you need to have a Mac-Book, the X-Code IDE, and for sharing your App a developer-license for 99$ a year [1]. So as a result the Android SDK is a powerful development kit for costless and efficient developing Apps for the Android OS offered by Google. 20

21 Bibliography [1] Apple. Mac developer Program. May [2] W. Article. Android (operating system). May [3] A. Becker. Android 2 Grundlagen und Programmierung. dpunkt-verl, Heidelberg, [4] Gartner. Gartner Says Worldwide Sales of Mobile Phones Declined 2 Percent in First Quarter of 2012; Previous Year-over-Year Decline Occurred in Second Quarter of May [5] Google. ADT Plugin for Eclipse, Android Developers. May [6] Google. Building and Running from the Command Line. May [7] Google. Input Events. May [8] Google. sdk manager packages.png PNG-Grafik. May Direct link: packages.png. [9] Google. system-architecture.jpg JPEG-Grafik. May Direct link: system-architecture.jpg. [10] Google. Using DDMS, Android Developers. May [11] Google. What is Android?, Android Developers. May

22 Appendix A Appendix A.1 Behind the scenes (Dalvik VM) As already mentioned before in the article the Android OS uses the Linux-Kernel as the base competent of its OS in the component stack. (cf. Section 1) Figure A.1: Android component stack [9] Building up on this Linux-Kernel, which acts as an abstraction layer between 22

23 A.1. Behind the scenes (Dalvik VM) 23 the hardware and the rest of the software stack, there will be the Linux typically libraries and the Android-Runtime layer. The Android-Runtime layer implements the Dalvik Virtual Machine, which is used to execute and observed every Android App in the Android-OS. The Dalvik Virtual Machine (DVM) was especially developed and customized for the Android OS to replace the standard Java Virtual Machine - which is used to execute the Java bytecode of an Java application with a better VM bringing more performance and resource-efficiency on devices with low-memory and relatively slow microprocessors. In case of this performance increase, every App on the Android OS gets granted a single DVM-Instance. This increases the security enormously, because no App can access the registers/ram allocated to an other running App which prevents memory injections. Futhermore theandroid-runtime layer is followed by the Application Framework and Application Layer so that every Android App which is executed in the Dalvik VM (Runtime Layer) has the ability to access the core methods of the Application Framework. This Application Framework offers the ability to use standard methods, e.g. the Window-Manager, Location-Manager or Telephony-Manger. The ability to access these features in a programmatic simple way is provided by the Android Software Development Kit, which was explained in the article.

24 Appendix B List of Abbreviations ADB Android-Debug-Bridge ADT Android Development Tools AVD Android-Virtual-Device API Application-Programming-Iterface CSS Cascading-Style-Sheets DDMS Davlik-Debug-Monitor-Server DVM Dalvik-Virtual-Machine GNU GPL GNU general public license GUI Graphical-User-Iintrace GPS global positioning system HTML hypertext markup language ID identifier IDE integrated development environment JDK java development kit OS operating system SDK Software-Development-Kit SMS short message service USB universal serial bus 24

25 APPENDIX B. LIST OF ABBREVIATIONS 25 VM virtual machine WYSIWYG What-You-See-Is-What-You-Get XML Extensible-Markup-Language

26 Appendix C Source code listings C.1 Java source code Listing C.1: MainActivity.java 1 package mm.dev. contact ; 2 3 import mm.dev. contact.r; 4 import android. app. Activity ; 5 import android. content. Intent ; 6 import android.os. Bundle ; 7 import android. util. Log ; 8 import android. view. View ; 9 import android. view. Window ; public class MainActivity extends Activity { /* Debbuging TAGS */ 14 public static final String MM_ WARNING = " mm. dev. WARNINGS "; 15 public static final String MM_ INFORMATION = " mm. dev. INFORMATION "; Override 19 protected void oncreate ( Bundle savedinstancestate ) { 20 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering oncreate ()"); 21 super. oncreate ( savedinstancestate ); 22 // remove Widget - Titlebar 23 this. requestwindowfeature ( Window. FEATURE_ NO_ TITLE ); 24 setcontentview ( R. layout. main ); 25 } public void onchoose ( final View button ) { 26

27 C.1. Java source code Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering onchoose ()"); // switching between both possible buttons. 31 switch ( button. getid () ) { 32 case R.id. contactbutton : 33 // launche the contact - explorer activity 34 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Starting ContactExplorerActivity "); 35 startactivity ( new Intent ( this, ContactExplorerActivity. class ) ); 36 break ; case R.id. camerabutton : 39 // launche the camera activity 40 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Starting CameraActivity "); 41 startactivity ( new Intent ( this, CameraActivity. class ) ); 42 break ; default : 45 Log.w( MainActivity. MM_WARNING, this. getclass (). getsimplename () + ": " + " undefind Button - ID [ " + button. getid () + " ] was committed!"); 46 break ; 47 } } }

28 C.1. Java source code 28 Listing C.2: CameraActivity.java 1 package mm.dev. contact ; 2 3 import mm.dev. contact.r; 4 import android. app. Activity ; 5 import android. content. Intent ; 6 import android. graphics. Bitmap ; 7 import android.os. Bundle ; 8 import android. util. Log ; 9 import android. view. View ; 10 import android. view. Window ; 11 import android. widget. ImageView ; 12 import android. widget. TextView ; 13 import android. widget. Toast ; public class CameraActivity extends Activity { private static final int CAMERA_ ACTIVITY_ CALL = 1911; 18 Override 20 protected void oncreate ( Bundle savedinstancestate ) { 21 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering oncreate ()"); 22 // TODO Auto - generated method stub 23 super. oncreate ( savedinstancestate ); 24 // remove Widget - Titlebar 25 this. requestwindowfeature ( Window. FEATURE_ NO_ TITLE ); 26 setcontentview (R. layout. camera_view ); 27 } public void takepicture ( final View view ) { 30 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering takepicture ()"); 31 Intent cameraresponseintent = new Intent ( android. provider. MediaStore. ACTION_IMAGE_CAPTURE ); 32 startactivityforresult ( cameraresponseintent, CAMERA_ ACTIVITY_ CALL ); } 35 Override 37 protected void onactivityresult ( int requestcode, int resultcode, Intent data ) { 38 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering onactivityresult () "); 39 Log.d( MainActivity. MM_INFORMATION, " requestcode : "+ requestcode + ", resultcode : " + resultcode + " ");

29 C.1. Java source code if( requestcode == CAMERA_ ACTIVITY_ CALL ){ 42 if( resultcode == Activity. RESULT_ OK ) { 43 // get the transmitted bitmap data and load it into the image view 44 Bitmap createdimage = ( Bitmap ) data. getextras (). get (" data "); 45 ImageView activityimageview = ( ImageView ) findviewbyid (R.id. cameraimage ); 46 activityimageview. setimagebitmap ( createdimage ); 47 TextView label = ( TextView ) findviewbyid ( R. id. pictureheadline ); 48 label. settext ( R. string. tx_taken_picture ); 49 } else { 50 Log.w( MainActivity. MM_WARNING, this. getclass (). getsimplename () + ": " + " Unkown resultcode [ " + resultcode + " ] no Operation defined."); 51 Toast. maketext ( this, " Please take an new picture!", Toast. LENGTH_LONG ). show (); 52 } 53 } 54 } 55 }

30 C.1. Java source code 30 Listing C.3: ContactExplorerActivity.java 1 package mm.dev. contact ; 2 3 import java. util. ArrayList ; 4 import mm.dev. contact.r; 5 import android. app. Activity ; 6 import android. app. ListActivity ; 7 import android. content. ContentResolver ; 8 import android. content. Intent ; 9 import android. database. Cursor ; 10 import android. os. Bundle ; 11 import android. provider. ContactsContract ; 12 import android. util. Log ; 13 import android. view. View ; 14 import android. view. Window ; 15 import android. widget. ArrayAdapter ; 16 import android. widget. ListView ; 17 import android. widget. Toast ; public class ContactExplorerActivity extends ListActivity { private static final int EDIT_ CONTACT_ CALL = 2511; 22 private ArrayAdapter < String > contactadapter = null ; /** Called when the activity is first created. */ Override 26 public void oncreate ( Bundle savedinstancestate ) { 27 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering oncreate ()"); 28 super. oncreate ( savedinstancestate ); 29 // remove Widget - Titlebar 30 this. requestwindowfeature ( Window. FEATURE_ NO_ TITLE ); setcontentview (R. layout. contact_overview ); ArrayList < String > mycontacts = new ArrayList < String >() ; // Accessing the contacts and save them into the mycontacts - ArryList 37 ContentResolver cr = getcontentresolver (); 38 Cursor zeiger = cr. query ( ContactsContract. Contacts. CONTENT_URI, null, null, null, null ); if( zeiger. getcount () > 0 ) { 41 while ( zeiger. movetonext ()){ 42 String contactname = zeiger. getstring ( zeiger. getcolumnindex ( ContactsContract. Contacts.

31 C.1. Java source code 31 DISPLAY_NAME ) ); 43 if( contactname!= null &&! mycontacts. contains ( contactname )) { 44 mycontacts. add ( contactname ); 45 } 46 } 47 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Conacts successfull read "); 48 } contactadapter = new ArrayAdapter < String >( this, 51 android.r. layout. simple_ list_ item_ 1, 52 mycontacts 53 ); 54 // sorting the contacts 55 contactadapter. sort ( null ); 56 // Connect the ListeView - View to the Adapter 57 setlistadapter ( contactadapter ); 58 } 59 Override 61 protected void onlistitemclick ( ListView l, View v, int position, long id) { 62 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering onlistitemclick ()"); String item = ( String ) getlistadapter (). getitem ( position ); String [] names = item. split (" "); 67 String forename = names [ 0]; 68 String surname = ""; if( names. length >= 2 ) { 71 if( names. length > 2) for ( int i = 1; i < names. length ; i++ ) { 72 surname += names [i]; 73 if( i < names. length -1 ) surname += " "; 74 } 75 else surname = names [ 1]; 76 } else { 77 Log.w( MainActivity. MM_WARNING, this. getclass (). getsimplename () + ": " + " Current contact [ "+ item + " ] has no surname, splitting and accessing the array would cause an Error! "); 78 }

32 C.1. Java source code Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Starting ContactInformationActivity and commit contact information within the Intent "); Intent contactinformations = new Intent ( this, ContactInformationActivity. class ); 85 contactinformations. putextra (" referenceid ", position ); 86 contactinformations. putextra (" vorname ", forename ); 87 contactinformations. putextra (" nachname ", surname ); this. startactivityforresult ( contactinformations, EDIT_CONTACT_CALL ); } 94 Override 96 protected void onactivityresult ( int requestcode, int resultcode, Intent data ) { 97 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering onactivityresult ()"); 98 Log. d( MainActivity. MM_ INFORMATION, " requestcode : " + requestcode + ", resultcode : " + resultcode + " "); if( requestcode == EDIT_ CONTACT_ CALL ) { 101 // Contact was edited 102 if( resultcode == Activity. RESULT_ OK ) { 103 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Activity. RESULT_ OK - > saving changes "); 104 // prepare new name 105 String name = data. getstringextra (" vorname ") + " " + data. getstringextra (" nachname "); 106 int pos = data. getintextra (" referenceid ", -1); 107 if( pos > 0 && this. contactadapter!= null ) { 108 contactadapter. remove ( ( String ) getlistadapter (). getitem ( pos ) ); 109 contactadapter. insert (name, pos ); 110 contactadapter. sort ( null ); 111 } else { 112 Log.d( MainActivity. MM_WARNING, this. getclass (). getsimplename () + ": " + " referenceid was

33 C.1. Java source code } transmitted - contact couldn t be saved "); 116 Toast. maketext (this, " Contact saved ", Toast. LENGTH_LONG ). show (); 117 } 118 } // TODO Auto - generated method stub 121 super. onactivityresult ( requestcode, resultcode, data ); 122 } 123 Override 125 protected void onresume () { 126 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering onresume ()"); 127 // TODO Auto - generated method stub 128 super. onresume (); } }

34 C.1. Java source code 34 Listing C.4: ContactInformationActivity.java 1 package mm.dev. contact ; 2 3 import mm.dev. contact.r; 4 import android. app. Activity ; 5 import android. content. Intent ; 6 import android.os. Bundle ; 7 import android. util. Log ; 8 import android. view. View ; 9 import android. view. Window ; 10 import android. widget. EditText ; public class ContactInformationActivity extends Activity { private int referenceid = 0; 15 Override 17 protected void oncreate ( Bundle savedinstancestate ) { 18 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering oncreate ()"); 19 // TODO Auto - generated method stub 20 super. oncreate ( savedinstancestate ); 21 // remove Widget - Titlebar 22 this. requestwindowfeature ( Window. FEATURE_ NO_ TITLE ); 23 setcontentview ( R. layout. contact_ detail ); // reading data committed by partent activty - through the intent. 26 final Bundle data = getintent (). getextras (); this. referenceid = data. getint (" referenceid "); // setting value of Fore - and Surname - Field. 31 (( EditText ) this. findviewbyid ( R.id. editvorname )). settext ( data. getstring (" vorname ") ); 32 (( EditText ) this. findviewbyid ( R.id. editnachname )). settext ( data. getstring (" nachname ") ); } public void saveandclose ( final View view ) { 37 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering saveandclose () "); Intent changes = new Intent (); 40 // putting data to the result intent 41 changes. putextra (" referenceid ", this. referenceid );

35 C.1. Java source code changes. putextra (" vorname ", (( EditText ) this. findviewbyid ( R.id. editvorname )). gettext (). tostring ()); 43 changes. putextra (" nachname ", (( EditText ) this. findviewbyid (R.id. editnachname )). gettext (). tostring ()); Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " setting result status : RESULT_ OK and committing intent data "); 46 setresult ( RESULT_ OK, changes ); 47 finish (); 48 } Override 53 public void onbackpressed () { 54 Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " Entering onbackpressed ()"); 55 // TODO Auto - generated method stub 56 super. onbackpressed (); Log.d( MainActivity. MM_INFORMATION, this. getclass (). getsimplename () + ": " + " setting result status : RESULT_CANCELED "); 59 setresult ( RESULT_ CANCELED, null ); 60 finish (); 61 } }

36 C.2. XML (layout) source code 36 C.2 XML (layout) source code Listing C.5: AndroidManifestxml 1 <? xml version =" 1.0 " encoding ="utf -8"?> 2 < manifest xmlns:android =" http: // schemas. android. com / apk / res / android " 3 package ="mm.dev. contact " 4 android:versioncode ="1" 5 android: versionname =" 1.0 " > 6 7 <uses - sdk android:minsdkversion ="11" /> 8 <uses - permission android:name =" android. permission. READ_CONTACTS "/> 9 <uses - permission android:name =" android. permission. CAMERA " /> < application 12 android:icon / ic_launcher " 13 android:label / app_name " > 14 < activity android: name =" MainActivity " > 15 <intent - filter > 16 < action android:name =" android. intent. action. MAIN " /> < category android:name =" android. intent. category. LAUNCHER " /> 19 </ intent - filter > 20 </ activity > 21 < activity android:name =" ContactExplorerActivity " android:label / app_name " ></ activity > 22 < activity android:name =" ContactInformationActivity ">< / activity > 23 < activity android: name =" CameraActivity " > </ activity > </ application > </ manifest >

37 C.2. XML (layout) source code 37 Listing C.6: main.xml 1 <? xml version =" 1.0 " encoding ="utf -8"?> 2 < LinearLayout xmlns:android =" http: // schemas. android. com / apk / res / android " 3 android: layout_ width =" match_ parent " 4 android:layout_height =" match_parent " 5 android: gravity =" center_ horizontal center_ vertical " 6 android: orientation =" vertical " > 7 8 < Button 9 android:id ="@+id/ contactbutton " 10 android: layout_ width =" wrap_ content " 11 android:layout_height =" wrap_content " 12 android:layout_marginbottom ="40 dip " 13 android: onclick =" onchoose " 14 android:text / bt_init_contact " 15 android:textsize ="14 pt" 16 android:padding ="10 dip " 17 android:background =" # ED" 18 /> <Button 21 android:id ="@+id/ camerabutton " 22 android: layout_ width =" wrap_ content " 23 android:layout_height =" wrap_content " 24 android:layout_margintop ="40 dip " 25 android:text / bt_init_camera " 26 android: onclick =" onchoose " 27 android:textsize ="14 pt" 28 android:padding ="10 dip " 29 android:background =" # ED" 30 /> </ LinearLayout >

38 C.2. XML (layout) source code 38 Listing C.7: Camera-View.xml 1 <? xml version =" 1.0 " encoding ="utf -8"?> 2 < LinearLayout xmlns:android =" http: // schemas. android. com / apk / res / android " 3 android: layout_ width =" match_ parent " 4 android:layout_height =" match_parent " 5 android: gravity =" center_ horizontal " > 6 7 < TableLayout 8 android: layout_ width =" wrap_ content " 9 android:layout_height =" match_parent " > < TableRow 12 android:id ="@+id/ tablerow2 " 13 android: layout_ width =" wrap_ content " 14 android:layout_height =" wrap_content " > < Button 17 android:id ="@+id/ button1 " 18 android: layout_ width =" wrap_ content " 19 android:layout_height =" wrap_content " 20 android:layout_margintop ="30 dip " 21 android:layout_marginbottom ="20 dip " 22 android: onclick =" takepicture " 23 android:text / bt_take_picture " 24 android:padding ="5 dip " 25 android:background =" # ED" /> </ TableRow > < TableRow 30 android:id ="@+id/ tablerow1 " 31 android: layout_ width =" wrap_ content " 32 android:layout_height =" wrap_content " 33 android: gravity =" center " > < TextView 36 android:id ="@+id/ pictureheadline " 37 android: layout_ width =" wrap_ content " 38 android:layout_height =" wrap_content " 39 android:text / tx_no_picture " 40 /> </ TableRow > < TableRow 45 android:id ="@+id/ tablerow3 " 46 android: layout_ width =" wrap_ content "

39 C.2. XML (layout) source code android:layout_height =" wrap_content " > < ImageView 50 android:id cameraimage " 51 android: layout_ width =" wrap_ content " 52 android:layout_height =" 300 dip " 53 android:contentdescription / ds_ pic_ description " / > </ TableRow > </ TableLayout > </ LinearLayout >

40 C.2. XML (layout) source code 40 Listing C.8: Contact-Detail.xml 1 <? xml version =" 1.0 " encoding ="utf -8"?> 2 < LinearLayout xmlns:android =" http: // schemas. android. com / apk / res / android " 3 android: layout_ width =" match_ parent " 4 android:layout_height =" match_parent " 5 android: gravity =" center_ horizontal " 6 android: orientation =" vertical " > 7 8 < TableLayout 9 android: layout_ width =" match_ parent " 10 android:layout_height =" wrap_content " 11 android:layout_margintop ="10 dip " > < TableRow 14 android:id ="@+id/ tablerow1 " 15 android: layout_ width =" wrap_ content " 16 android:layout_height =" wrap_content " 17 android:layout_marginbottom ="5 dip " > < TextView 20 android: layout_ width =" wrap_ content " 21 android:layout_height =" wrap_content " 22 android:text / tx_vorname " 23 android:padding ="5 dip "/> < EditText 26 android:id ="@+id/ editvorname " 27 android: layout_ width =" wrap_ content " 28 android:layout_height =" wrap_content " 29 android:ems ="10" 30 android: inputtype =" text " 31 > < requestfocus / > 34 </ EditText > </ TableRow > < TableRow 39 android:id ="@+id/ tablerow2 " 40 android: layout_ width =" wrap_ content " 41 android:layout_height =" wrap_content " > < TextView 44 android: layout_ width =" wrap_ content " 45 android:layout_height =" wrap_content " 46 android:text / tx_nachname "

41 C.2. XML (layout) source code android:padding ="5 dip "/> < EditText 50 android:id editnachname " 51 android: layout_ width =" wrap_ content " 52 android:layout_height =" wrap_content " 53 android:ems ="10" 54 android:inputtype =" text " /> </ TableRow > < TableRow 59 android:id tablerow3 " 60 android: layout_ width =" wrap_ content " 61 android:layout_height =" wrap_content " > 62 </ TableRow > < TableRow 65 android:id tablerow4 " 66 android: layout_ width =" wrap_ content " 67 android:layout_height =" wrap_content " > < TableRow 70 android:id tablerow5 " 71 android: layout_ width =" wrap_ content " 72 android:layout_height =" wrap_content " > 73 </ TableRow > </ TableRow > 76 </ TableLayout > < Button 79 android:id savecontactinformations " 80 android: layout_ width =" wrap_ content " 81 android:layout_height =" wrap_content " 82 android:text / bt_save_contact " 83 android: onclick =" saveandclose " 84 android:layout_margintop ="50 dip " 85 android:background =" # ED" 86 android:padding ="5 dip " /> </ LinearLayout >

42 C.2. XML (layout) source code 42 Listing C.9: Contact-Overview.xml 1 <? xml version =" 1.0 " encoding ="utf -8"?> 2 < LinearLayout xmlns:android =" http: // schemas. android. com / apk / res / android " 3 android:layout_width =" fill_parent " 4 android:layout_height =" fill_parent " 5 android: orientation =" vertical " 6 android:padding ="10 dip "> 7 8 < ListView 9 android:id ="@+id/ android:list " 10 android: layout_ width =" fill_ parent " 11 android:layout_height =" wrap_content " > 12 </ ListView > </ LinearLayout >

43 C.2. XML (layout) source code 43 Listing C.10: values.xml 1 <? xml version =" 1.0 " encoding ="utf -8"?> 2 < resources > 3 4 <! -- MainActivity START -- > 5 6 <! -- Textviews / Descriptions -- > 7 8 <! -- Buttons --> 9 <string name =" bt_init_contact ">Contact - Example </ string > 10 <string name =" bt_init_camera ">Camera - Example </ string > <! -- Main END --> <! -- ContactExplorerActivity START --> <! -- Textviews / Descriptions -- > 20 < string name =" app_name "> ContactAndCameraExplorer </ string > <! -- Buttons --> <! -- ContactExplorerActivity END --> <! -- ContactInformationActivity START --> <! -- Textviews / Descriptions -- > 32 < string name =" tx_vorname ">Forename: </ string > 33 < string name =" tx_nachname ">Surname: </ string > <! -- Buttons --> 36 < string name =" bt_ save_ contact " > Save contact informations < / string > <! -- ContactInformationActivity END --> <! -- CameraActivity START -- > <! -- Textviews / Descriptions -- > 44 < string name =" tx_ taken_ picture " > Recently taken picture: </ string > 45 <string name =" tx_no_picture ">No picture taken.</ string >

44 C.2. XML (layout) source code <! -- Buttons --> 47 < string name =" bt_take_picture ">Take a new picture </ string > < string name =" ds_ pic_ description " > Picture take via the Camera </ string > <! -- CameraActivity END -- > </ resources >