PES INSTITUTE OF TECHNOLOGY (BSC) IV MCA, Second IA Test, May 2017 Mobile Applications (13MCA456) Solution Set Faculty: Jeny Jijo

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1 PES INSTITUTE OF TECHNOLOGY (BSC) IV MCA, Second IA Test, May 2017 Mobile Applications (13MCA456) Solution Set Faculty: Jeny Jijo 1) Explain the techniques to handle changes in screen orientation in Android [10] Give detailed description of below techniques of screen orientation Anchoring The easiest way is to anchor your views to the four edges of the screen. When the screen orientation changes, the views can anchor neatly to the edges. Resizing and repositioning Whereas anchoring and centralizing are simple techniques to ensure that views can handle changes in screen orientation, the ultimate technique is resizing each and every view according to the current screen orientation. 2 (a) How do you persist the state information during changes in configuration in Android? [5] To preserve the state of an activity, you could always implement the onpause() event, and then use your own ways to preserve the state of your activity, such as using a database, internal or external file storage, etc. onpause() - This event is always fired whenever an activity is killed or pushed into the background. If you simply want to preserve the state of an activity so that it can be restored later when the activity is re-created (such as when the device changes orientation), a much simpler way would be to implement the onsaveinstancestate() method, as it provides a Bundle object as an argument so that you can use it to save your activity s public void onsaveinstancestate(bundle outstate) //---save whatever you need to persist--- outstate.putstring( ID, ); super.onsaveinstancestate(outstate); When an activity is re-created, the oncreate() event is first fired, followed by the onrestoreinstancestate() event, which enables you to retrieve the state that you saved previously in the onsaveinstancestate event through the Bundle object in its public void onrestoreinstancestate(bundle savedinstancestate) super.onrestoreinstancestate(savedinstancestate); //---retrieve the information persisted earlier--- String ID = savedinstancestate.getstring( ID );

2 To extract the saved data, you can extract it in the oncreate() event, using the getlastnonconfigurationinstance() method, like public void oncreate(bundle savedinstancestate) super.oncreate(savedinstancestate); setcontentview(r.layout.main); Log.d( StateInfo, oncreate ); String str =(String)getLastNonConfigurationInstance(); (b) Explain Picker Views briefly. [5] Selecting the date and time is one of the common tasks you need to perform in a mobile application. Android supports this functionality through the TimePicker and DatePicker views. The TimePicker view enables users to select a time of the day, in either 24-hour mode or AM/PM mode. The TimePicker displays a standard UI to enable users to set a time. By default, it displays the time in the AM/PM format. If you wish to display the time in the 24-hour format, you can use the setis24hour View() method. To programmatically get the time set by the user, use the getcurrenthour() and getcurrentminute() methods: Toast.makeText(getBaseContext(), Time selected: +timepicker.getcurrenthour() + : + timepicker.getcurrentminute(), Toast.LENGTH_SHORT).show(); Using the DatePicker, you can enable users to select a particular date on the activity <DatePicker android:layout_width= wrap_content android:layout_height= wrap_content /> 3(a) Explain Spinner View [4 ] The ListView displays a long list of items in an activity, but sometimes you may want your user interface to display other views, and hence you do not have the additional space for a full-screen view like the ListView. In such cases, you should use the SpinnerView. The SpinnerView displays one item at a time from a list and enables users to choose among them. Views can fire events when users interact with them. For example, when a user touches a Button view, you need to service the event so that the appropriate action can be performed. To do so, you need to explicitly register events for views. Button btn1 = (Button)findViewById(R.id.btn1); btn1.setonclicklistener(btnlistener); //create an anonymous class to act as a button clicklistener private OnClickListener btnlistener = new OnClickListener() public void onclick(view v)

3 Toast.makeText(getBaseContext(), ((Button) v).gettext() + was clicked, Toast.LENGTH_LONG).show();; (b) How does Image Switcher work as User Interface in Android? [04] Sometimes you don t want an image to appear abruptly when the user selects it in the Gallery view you might, for example, want to apply some animation to the image when it transits from one image to another. In this case, you need to use the ImageSwitcher together with the Gallery view. <Gallery android:layout_width= fill_parent android:layout_height= wrap_content /> <ImageSwitcher android:layout_width= fill_parent android:layout_height= fill_parent android:layout_alignparentleft= true android:layout_alignparentright= true android:layout_alignparentbottom= true /> imageswitcher = (ImageSwitcher) findviewbyid(r.id.switcher1); imageswitcher.setfactory(this); imageswitcher.setinanimation(animationutils.loadanimation(this, android.r.anim.fade_in)); imageswitcher.setoutanimation(animationutils.loadanimation(this, android.r.anim.fade_out)); Gallery gallery = (Gallery) findviewbyid(r.id.gallery1); gallery.setadapter(new ImageAdapter(this)); gallery.setonitemclicklistener(new OnItemClickListener() public void onitemclick(adapterview<?> parent, View v, int position, long id) imageswitcher.setimageresource(imageids[position]); In the oncreate() method, you get a reference to the ImageSwitcher view and set the animation, specifying how images should fly in and out of the view When an image is selected in the Gallery view, it will appear by fading in. When the next image is selected, the current image will fade out. If you want the image to slide in from the left and slide out to the right when another image is selected, try the following animation: imageswitcher.setinanimation(animationutils.loadanimation(this, android.r.anim.slide_in_left)); imageswitcher.setoutanimation(animationutils.loadanimation(this, android.r.anim.slide_out_right));

4 4) Describe Menus with views in Android [10] Menus are useful for displaying additional options that are not directly visible on the main UI of an application. There are two main types of menus in Android: a. Options menu - Displays information related to the current activity. In Android, you activate the options menu by pressing the MENU key. b. Context menu - Displays information related to a particular view on an activity. In Android,to activate a context menu you tap and hold on to it. The option menu is displayed whenever the user presses the MENU button. The menu items displayed vary according to the current activity that is running. A context menu is that is displayed when the user presses and holds on a hyperlink displayed on the page. The menu items displayed vary according to the component or view currently selected. To activate the context menu, the user selects an item on the screen and either taps and holds it or simply presses the center button on the directional keypad. 5) a Define and describe Content Provider [4] In Android, using a content provider is the recommended way to share data across packages. A content provider behaves very much like a database you can query it, edit its content, as well as add or delete its content. However, unlike a database, a content provider can use different ways to store its data. The data can be stored in a database, in files, or even over a network. Android has many useful content providers Browser - Stores data such as browser bookmarks, browser history, and so on CallLog - Stores data such as missed calls, call details, and so on Contacts - Stores contact details MediaStore - Stores media files such as audio, video and images Settings - Stores the device s settings and preferences We can create our own content providers. To query a content provider, you specify the query string in the form of a URI, with an optional specifier for a particular row. The format of the query URI is as follows: <standard_prefix>://<authority>/<data_path>/<id> The standard prefix for content providers is always content://. The authority specifies the name of the content provider The data path specifies the kind of data requested The id specifies the specific record requested (b) How does Android helps in getting Location Based Data. [6] We can use a GPS receiver to find your location easily. However, GPS requires a clear sky to work and hence does not always work indoors or where satellites can t penetrate. Another effective way to locate your position is through cell tower triangulation. The advantage of cell tower triangulation is that it works indoors, without the need to obtain information from

5 satellites.cell tower triangulation works best in densely populated areas where the cell towers are closely located. A third method of locating your position is to rely on Wi-Fi triangulation. Rather than connect to cell towers, the device connects to a Wi-Fi network and checks the service provider against databases to determine the location serviced by the provider. Of the three methods described here, Wi-Fi triangulation is the least accurate. On the Android, the SDK provides the LocationManager class to help your device determine the user s physical location. In Android, location-based services are provided by the LocationManager class, located in the android.location package. Using the LocationManager class, the application can obtain periodic updates of the device s geographical locations, as well as fire an intent when it enters the proximity of a certain location. To be notified whenever there is a change in location, you need to register a request for location changes so that your program can be notified periodically. This is done via the requestlocationupdates() method: lm.requestlocationupdates(locationmanager.gps_provider,0,0,locationlistener);. 6) Explain the basic ways of persisting data in Android. [10] In Android, you can use the classes in the java.io namespace to do so. Saving to Internal Storage The first way to save files in your Android application is to write to the device s internal storage. To save text into a file, you use the FileOutputStream class. The openfileoutput() method opens a named file for writing, with the mode specified. In this example, you use the MODE_WORLD_READABLE constant to indicate that the file is readable by all other applications: FileOutputStream fout = openfileoutput( textfile.txt, MODE_WORLD_READAB LE); Other modes MODE_PRIVATE MODE_APPEND (for appending to an existing file), and MODE_WORLD_WRITEABLE (all other applications have write access to the file). To convert a character stream into a byte stream, you use an instance of the OutputStreamWriter class, by passing it an instance of the FileOutputStream object: OutputStreamWriter osw = new OutputStreamWriter(fOut); Then the write() method is used to write the string to the file. To ensure that all the bytes are written to the file, use the flush() method. Finally, use the close() method to close the file: osw.write(str); osw.flush(); osw.close(); To read the content of a file, you use the FileInputStream class, together with the InputStreamReader class: FileInputStream fin = openfileinput ( textfile.txt );

6 InputStreamReader isr = new InputStreamReader(fIn); The content is read in blocks of 100 characters into a buffer (character array). The characters read are then copied into a String object. Saving to External Storage (SD Card) Sometimes, it would be useful to save them to external storage (such as an SD card) because of its larger capacity, as well as the capability to share the files easily with other users (by removing the SD card and passing it to somebody else). to save the text entered by the user in the SD card, modify the onclick() method of the Save button For saving relational data, using a database is much more efficient. Android uses the SQLite database system. The database that you create for an application is only accessible to itself; other applications will not be able to access it. For Android, the SQLite database that you create programmatically in an application is always stored in the /data/data/<package_name>/databases folder. 7 (a) Explain the basics of Objective-C. [4] Objective-C is an object-oriented language based on the C programming language. Objective-C was created in the early 1980s by Brad Cox and Tom Love, and gained popularity when Steve Jobs and NeXT licensed the language from them, and made Objective- C the main language on NeXT s NextSTEP operating system. Objective-C requires developers to declare a class in an interface and then define the implementation, something that non-c developers find off-putting about the language. Classes The interface of Objective-C classes is defined in a header file for each interface. Usually the filenames of the header match the class name. For example, you can create a header file named Dog : Animal // instance variables // Method You are telling the compiler that a new class named Dog, which is a subclass of animal, is being declared. Any instance variables are declared between the curly brackets, and methods are declared between the end of the curly bracket and keyword. The actual implementation of the Dog class would look like this: #import Dog // method Instance Variables

7 The attributes that are declared between the curly brackets are instance variables. Instance variables are declared like local or global variables, but have a different scope. Instance variables by default are visible in all instance methods of a class and its subclasses. Methods Methods can be declared as either instance methods or class methods. Instance methods are called by sending a message directly to the instance of the class, which means you need to have your own instance of the class before you can call these methods. Instance methods are prefixed with a minus sign (-). -(return_type)method_name:(argumenttype1) argumentname1 joiningargument2:( argumenttype2 )argumentname2... joiningargumentn:( argumenttype n )argumentname n body of the function If Statements if( a < 20 ) /* if condition is true then print the following */ NSLog(@"a is less than 20\n" ); else /* if condition is false then print the following */ NSLog(@"a is not less than 20\n" ); for (int i = 1; i <= 10; i++) NSLog(@"%d", i); To loop through a collection of NSString objects in an NSArray and print them all out, you could use the following format. for (NSString* currentstring in myarrayofstrings) // code that may cause the (NSException *e) //exception is caught and logic should be added to handle the // code that should be executed no matter if an exception has occurred or not. 7(b) Explain the tools required for developing Windows Phone 7 software [5] To develop software for Windows Phone 7 you need a machine running Windows (Vista or Windows 7), Visual Studio 2010, and the Phone SDK, as well as a Windows Phone 7 device to test with. Hardware HTC, Nokia, and Samsung are currently manufacturing Windows Phone 7 devices. Device resolutions are pixels, and most are outfitted with both front- and

8 rear-facing cameras, and screens from 4.3 to 4.7 inches. They are primarily found on GSM carriers. Visual Studio and Windows Phone SDK Code for the Windows Phone is written in the.net Framework, either with XNA (Microsoft s run time for game development), or a custom version of Silverlight (Microsoft s Rich Internet Application framework). User interfaces are created with XAML (extensible Application Markup Language). The Windows Phone SDK works with Visual Studio Express. The SDK also installs a specialized version of Expression Blend set up to work specifically for Windows Phone 7 development. Expression Blend is a tool developed by Microsoft for working with XAML. It provides similar functionality to Visual Studio, though its layout is designed to be more user friendly to designers. The Windows Phone SDK installer includes: Visual Studio 2010 Express for Windows Phone (if you do not have another version of Visual Studio 2010 installed) Windows Phone Emulator Windows Phone SDK Assemblies Silverlight 4 SDK Phone SDK 7.1 Extensions for XNA Game Studio Expression Blend for Windows Phone 7 WCF Data Services Client for Windows Phone Microsoft Advertising SDK To install the Windows Phone SDK you need: Vista (x86 or x64) or Windows 7 (x86 or x64) 4 GB of free disk space 3 GB of RAM DirectX 10 or above capable graphics card with a WDDM 1.1 driver The Windows Phone 7 emulator is a very powerful tool. Not just a simulator, the emulator runs a completely sandboxed virtual machine in order to better mimic the actual device. It also comes with some customization and runtime tools to manipulate sensors that are being emulated on the device, including GPS and accelerometer, as well as provide a way to capture screenshots while testing and developing applications.