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Winners of the Ice Cream Sandwich VS iOS5 contest

<div dir="ltr" style="text-align: left;" trbidi="on">Dear readers we are glad to announce the winners of our Ice Cream Sandwich VS iOS5 contest: The winners of the first prize: Android a Complete Course: Jim from <a href="http://sakiko.com/">http://sakiko.com/</a> and <a href="http://www.blogger.com/profile/04325201851097237982" target="_blank">Believer</a>. The winner of the second prize: Android a Quick Course: <a href="http://www.blogger.com/profile/05724717613575721151" target="_blank">Corneliu Dascalu</a> The winners of the third prize Android, an Enterprise Edition Vision: <a href="http://www.blogger.com/profile/11125791667492488384" target="_blank">Will.i.am</a> for the winners please contact me at <a href="mailto:m.s.ramzy@gmail.com">m.s.ramzy@gmail.com</a> to send you the copies of the books thanks a lot for all the participants and good luck next time. </div>

Dear readers we are glad to announce the winners of our Ice Cream Sandwich VS iOS5 contest: The winners of the first prize: Android a Comp...

Ice Cream Sandwich GridLayout

<div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on">Android 4.0 (Ice Cream Sandwich) introduced a new type of layouts: the Gridlayout. Gridlayout is like the <Table> tag in HTML. child widgets are arranged in Cells made of Rows and Columns. Grid layout is a ViewGroup that can be used in constructing dashboard activities like that one in the Google Plus application: <div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/October/gplus.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/October/gplus.jpg" width="192" /></a></div> so let's see what we can do with the GridLayout: we'll construct a simple dashboard layout like this:</div><pre class="brush:xml"><?xml version="1.0" encoding="utf-8"?> <GridLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:rowCount="5" android:columnCount="3" > <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 1" android:layout_row="0" android:layout_column="0" android:layout_marginLeft="5dp" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 2" android:layout_row="0" android:layout_column="1" android:layout_margin="5dp" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 3" android:layout_row="1" android:layout_column="0" android:layout_margin="5dp" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 4" android:layout_row="1" android:layout_column="1" android:layout_margin="5dp" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 5" android:layout_row="2" android:layout_column="0" android:layout_margin="5dp" /> </GridLayout> </pre></div><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/October/device1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/October/device1.png" width="192" /></a></div> Widgets are placed in position specified by android:layout_column and android:layout_row properties. we can organize the widgets in a similar way by using the new Space View like this:</div><?xml version="1.0" encoding="utf-8"?> <GridLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:rowCount="5" android:columnCount="3" > <Space android:layout_width="5dp" android:layout_height="5dp"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 1" android:layout_row="0" android:layout_column="0" /> <Space android:layout_width="5dp" android:layout_height="5dp"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 2" android:layout_row="0" android:layout_column="1" /> <Space android:layout_width="5dp" android:layout_height="5dp"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 3" android:layout_row="1" android:layout_column="0" /> <Space android:layout_width="5dp" android:layout_height="5dp"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 4" android:layout_row="1" android:layout_column="1" /> <Space android:layout_width="5dp" android:layout_height="5dp"/> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 5" android:layout_row="2" android:layout_column="0" /> <Space android:layout_width="5dp" android:layout_height="5dp"/> </GridLayout> <div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/October/device2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/October/device2.png" width="192" /></a></div> </div>

Android 4.0 (Ice Cream Sandwich) introduced a new type of layouts: the Gridlayout . Gridlayout is like the <Table> tag in HTML . chil...

Contest: Do you think Android Ice Cream Sandwich will beat Apple iOS 5

<div dir="ltr" style="text-align: left;" trbidi="on">Hello everybody. Google will release the next major Android update: Android 4.0 (Ice cream Sandwich) along with it's next flagship phone: the Nexus Prime. Join our Contest and have the chance to win a copy of one of these wonderful Android books: <ol style="text-align: left;"><li><a href="http://www.android2ee.com/index.php?option=com_content&view=article&id=70&Itemid=102&lang=en">Android, A Complete Course, From Basics To Enterprise Edition.</a></li><li><a href="http://www.android2ee.com/index.php?option=com_content&view=article&id=71&Itemid=104&lang=en">Android, A Quick Course.</a></li><li><a href="http://www.android2ee.com/index.php?option=com_content&view=article&id=59&Itemid=105&lang=en">Android, An Enterprise Edition Vision.</a></li></ol><div class="separator" style="clear: both; text-align: center;"></div><table><tbody><tr> <td> <a href="http://www.android2ee.com/index.php?option=com_content&view=article&id=70&Itemid=102&lang=en" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="200" src="http://www.android2ee.com/images/stories/couv-android/couv-complet-course.jpg" width="141" /></a></td> <td> <a href="http://www.android2ee.com/index.php?option=com_content&view=article&id=71&Itemid=104&lang=en" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="200" src="http://www.android2ee.com/images/stories/couv-android/couv-quick-course.jpg" width="141" /></a></td> <td> <a href="http://www.android2ee.com/index.php?option=com_content&view=article&id=59&Itemid=105&lang=en" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="200" src="http://www.android2ee.com/images/stories/couv-android/couv-Enterprise.jpg" width="141" /></a></td> </tr></tbody></table><div> </div><div>all you've got to do is to drop a comment answering the following question:</div><div>Do you think Android Ice Cream Sandwich will beat Apple iOS 5 ?</div><div> </div><div>the contest ends on November 7th, winners will be announced then.</div><div>waiting for your comments</div> </div>

Hello everybody. Google will release the next major Android update: Android 4.0 (Ice cream Sandwich) along with it's next flagship phon...

Symbyo Technologies: Cloud Computing and Mobile Application Development

Android Developers Blog: Preview of Google TV Add-on for the Android SDK

Official Google Blog: Supercharging Android: Google to Acquire Motorola Mobility

Android Developing: Remove Auto focus from Edit Text

Android Developing: Remove Auto focus from Edit Text : "When start Android application, it always auto focus EditText box. Here we give...

Implementing Search activities

<div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on">Most Android phones have a search button. this button is used to search contacts,applications or anything on the phone. We can make use of the search functionality in our apps. In this post we're going to see how to implement search functionality to search for entries stored in a databaseand display them in a ListView.</div><div closure_uid_ghg7ej="237"> </div><div closure_uid_ghg7ej="237">Creating database:</div></div>our database has two tables: Countries and Names: <pre class="brush:java" closure_uid_ghg7ej="312">public class DBHelper extends SQLiteOpenHelper { public DBHelper(Context context) { super(context, "DemoDB", null, 1); } @Override public void onCreate(SQLiteDatabase db) { StringBuilder builder=new StringBuilder(); // countries table builder.append("CREATE TABLE Countries "); builder.append("(_id INTEGER PRIMARY KEY AUTOINCREMENT,"); builder.append("NAME TEXT) "); db.execSQL(builder.toString()); // Names table // Virtual table for full text search builder.setLength(0); builder.append("CREATE VIRTUAL TABLE NAMES USING FTS3"); builder.append("("); builder.append("name TEXT) "); db.execSQL(builder.toString()); builder=new StringBuilder(); //dummy data InsertData(db); } void InsertData(SQLiteDatabase db) { ContentValues cv=new ContentValues(); cv.put("NAME","USA"); db.insert("Countries", "NAME", cv); cv.put("NAME","UK"); db.insert("Countries", "NAME", cv); cv.put("NAME","Spain"); db.insert("Countries", "NAME", cv); cv.put("NAME","ITALY"); db.insert("Countries", "NAME", cv); cv.put("NAME","Germany"); db.insert("Countries", "NAME", cv); cv=new ContentValues(); cv.put("name","John"); db.insert("NAMES", "name", cv); cv.put("name","Jack"); db.insert("NAMES", "name", cv); cv.put("name","Ann"); db.insert("NAMES", "name", cv); cv.put("name","Adam"); db.insert("NAMES", "name", cv); cv.put("name","Sarah"); db.insert("NAMES", "name", cv); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub } }</pre></div>notice that the Names table is a VIRTUAL table. we created it as virtual to make use of Full Text Search (FTS3) feature in SQLite. this feature makes queries faster than that in regular tables.</div>then we add two functions to retrieve all rows from both tables: <pre class="brush:java">/** * Return all countries * @return */ public ArrayListgetCountries(){ ArrayList countries=new ArrayList(); SQLiteDatabase db=this.getReadableDatabase(); Cursor c=db.rawQuery("select * from Countries", null); while(c.moveToNext()){ String country=c.getString(1); countries.add(country); } c.close(); return countries; } /** * Return all names * @return */ public ArrayListgetNames(){ ArrayList names=new ArrayList(); Cursor c=this.getReadableDatabase().rawQuery("select * FROM Names", null); while(c.moveToNext()){ String name=c.getString(0); names.add(name); } c.close(); return names; }</pre></div>and another two functions to retrieve data based on a search string: <pre class="brush:java">/** * Return all countries based on a search string * @return */ public ArrayListgetCountriesSearch(String query){ ArrayList countries=new ArrayList(); SQLiteDatabase db=this.getReadableDatabase(); Cursor c=db.rawQuery("select * from Countries where NAME LIKE '%"+query+"%'", null); while(c.moveToNext()){ String country=c.getString(1); countries.add(country); } c.close(); return countries; } /** * Return all names based on a search string * we use the MATCH keyword to make use of the full text search * @return */ public ArrayListgetNamesSearch(String query){ ArrayList names=new ArrayList(); Cursor c=this.getReadableDatabase().rawQuery("select * FROM Names WHERE name MATCH '"+query+"'", null); while(c.moveToNext()){ String name=c.getString(0); names.add(name); } c.close(); return names; }</pre></div> Implementing The activity:</div>then we will create our activity that has a list view like this: <pre class="brush:xml" closure_uid_ghg7ej="313" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"><?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <ListView android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/list"/> </LinearLayout></pre></div><div closure_uid_ghg7ej="251" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/Search%20Activity/search.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320px" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/Search%20Activity/search.bmp" /></a></div></div>we load data from database like this: <pre class="brush:java">public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); list=(ListView)findViewById(R.id.list); DBHelper helper=new DBHelper(this); ArrayList items=helper.getNames(); ArrayAdapter adapter=new ArrayAdapter(this, android.R.layout.simple_list_item_1,items); list.setAdapter(adapter); }</pre></div><div closure_uid_ghg7ej="315"> </div><div closure_uid_ghg7ej="315">Handling the search dialog:</div></div>In order to handle the search dialog ourselves we need to create a xml file with search configurations such as the search dialog title, voice search capabilities, content provider for auto complete and so on. we create a file with the name searchable.xml in res/xmldirectory: <pre class="brush:xml"><?xml version="1.0" encoding="utf-8"?> <searchable xmlns:android="http://schemas.android.com/apk/res/android" android:label="@string/app_name" android:hint="@string/hint" > </searchable></pre></div>the android:hint attribute denotes a string that acts as a water mark on the search text box. then we need to add an Intent Filter in out app's AndroidManifest.xml file to our activity to handle the search dialog: <pre class="brush:xml"><activity android:name=".MainActivty" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> <intent-filter> <action android:name="android.intent.action.SEARCH" /> </intent-filter> <meta-data android:name="android.app.searchable" android:resource="@xml/searchable"/> </activity></pre> </div><div closure_uid_ghg7ej="317">Understanding the Search process:</div></div> when you press the search button, type some text and click on search the activit's onSearchRequested() function is called, then an Intent with the action Intent.ACTION_SEARCH is created and you activity is re-created with this intent. the search intent has you search string as a string extra with the name SearchManager.QUERY. also it can carry a bundle of other extras with the name SearchManager.APP_DATA.</div> what if the device doesn't have a Search button:</div>not all Android devices have a search button, so we can start the search dialog manually by calling the activity's onSearchRequested() from a button or a menu item: <pre class="brush:java">@Override public boolean onCreateOptionsMenu(Menu menu) { menu.add("Search").setOnMenuItemClickListener(new OnMenuItemClickListener() { @Override public boolean onMenuItemClick(MenuItem item) { //launch the search dialog onSearchRequested(); return true; } }); return true; }</pre></div><div closure_uid_ghg7ej="322"> </div><div closure_uid_ghg7ej="322">Adding extras to the search dialog:</div></div>we can pass some extra data as a bundle with our search dialog or an initial search string by overriding the activity's onSearchRequested(): <pre class="brush:java">@Override public boolean onSearchRequested() { Bundle bundle=new Bundle(); bundle.putString("extra", "exttra info"); // search initial query startSearch("Country", false, bundle, false); return true; }</pre></div> Handling the search query:</div><div closure_uid_ghg7ej="324"> </div><div closure_uid_ghg7ej="324">we said before that the search query is passed as a String extra when our activity is re-created. so we can handle the searcgh string in our onCreate() like this:</div><pre class="brush:java" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); list=(ListView)findViewById(R.id.list); DBHelper helper=new DBHelper(this); Intent intent=getIntent(); // if the activity is created from search if(intent.getAction().equals(Intent.ACTION_SEARCH)){ // get search query String query=intent.getStringExtra(SearchManager.QUERY); ArrayList items=helper.getNamesSearch(query); //get extras, just for demonstration Bundle bundle=intent.getBundleExtra(SearchManager.APP_DATA); String info=bundle.getString("extra"); Log.v("extra", info); //bind the list ArrayAdapter adapter=new ArrayAdapter(this, android.R.layout.simple_list_item_1,items); list.setAdapter(adapter); } //activity created normally else{ ArrayList items=helper.getNames(); ArrayAdapter adapter=new ArrayAdapter(this, android.R.layout.simple_list_item_1,items); list.setAdapter(adapter); } helper.close(); }</pre></div><div closure_uid_ghg7ej="368" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;"> </div><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/Search%20Activity/search2.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320px" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/Search%20Activity/search2.bmp" /></a></div></div> we just extract the search string and any other extras and perform our search logic based on the search string. and that's was all about implementing search</div>

Most Android phones have a search button. this button is used to search contacts,applications or anything on the phone. We can make use of...

<div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on">In this post we will see how can a client application call the methods of a service defined in another application. this is achieved through Android Interface Definition Language (AIDL). AIDL is a java like language that enables you to define an interface that both the application defining the service and the client application implement it. <div closure_uid_siyhg3="239"><div closure_uid_siyhg3="260">the interface defines the functions that are needed to be called in the client application.</div></div><div closure_uid_siyhg3="232"> </div><div closure_uid_siyhg3="232">Defining the AIDL file:</div>AIDL syntax is similar to that of Java, we can use the following data types in AIDL: <ol><li>primitive data types: int, long, char, boolean,....</li><li>String.</li><li>CharSequence.</li><li>List (ArrayList,Vector,...).</li></ol> <ol><li>the AIDL file is defined as follows: open a notepad file and paste the following code in it: <pre class="brush:java">package com.mina.servicedemo; // service interface interface IRemoteService { //sample method String sayHello(String message); }</pre>take care of the package name com.mina.servicedemo. we defined a methods sayHello(String message) that returns a string.</li><li>save the file with the name IRemoteService and change it's extension to .aidl.</li><li>copy the file to the src folder of your project.</li><li>once you save and build the file, Android generates an interface java file with the name IRemoteService.java in the gen folder if the project.</li></ol> </div><div closure_uid_siyhg3="243">Defining the Service:</div>now we want our service to expose this interface to client applications, so we return an implementation of the service in the onBind() method of our service: <pre class="brush:java">package com.mina.servicedemo; import com.mina.servicedemo.IRemoteService.Stub; import android.app.Service; import android.content.Intent; import android.os.IBinder; import android.os.RemoteException; import android.widget.Toast; public class DemoService extends Service { @Override public IBinder onBind(Intent arg0) { return mBinder; } // implementation of the aidl interface private final IRemoteService.Stub mBinder=new Stub() { @Override public String sayHello(String message) throws RemoteException { return "Hello "+message; } }; } }</pre></div>the last thing to do in the service is to make its exported attribute in the AndroidManifest.xml file set to true like this: <pre class="brush:xml"><service android:name="DemoService" android:exported="true"></service></pre>our app structure can be like this: <div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/AIDL/aidl.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/AIDL/aidl.bmp" /></a></div><div closure_uid_siyhg3="248"> </div><div closure_uid_siyhg3="259">Consuming the service at the client application:</div>now to our client application where we want to invoke methods from our service. the client application is a separate application with a different package name than that where the service is defined. the client application needs a reference to the AIDL interface defined in the original applcation, this is done through the following steps: <ol><li>in the client applicatio create a package with the same package name of that the service is defined in: com.mina.servicedemo.</li><li>copy the AIDL file in this package.</li><li closure_uid_siyhg3="261" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none;">save and build and a new file called IRemoteService.java is generated. your app structure should be like this: </li></ol><div class="separator" style="border-bottom: medium none; border-left: medium none; border-right: medium none; border-top: medium none; clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/AIDL/aidl2.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/August/AIDL/aidl2.bmp" /></a></div>and we invoke the servcice methods in our activity like this: <pre class="brush:java">package com.mina.serviceclient; import com.mina.servicedemo.IRemoteService; import android.app.Activity; import android.content.ComponentName; import android.content.Context; import android.content.Intent; import android.content.ServiceConnection; import android.os.Bundle; import android.os.IBinder; import android.os.RemoteException; import android.util.Log; public class MainActivity extends Activity { IRemoteService mRemoteService; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Intent serviceIntent=new Intent(); serviceIntent.setClassName("com.mina.servicedemo", "com.mina.servicedemo.DemoService"); boolean ok=bindService(serviceIntent, mServiceConnection,Context.BIND_AUTO_CREATE); Log.v("ok", String.valueOf(ok)); } private ServiceConnection mServiceConnection=new ServiceConnection() { @Override public void onServiceDisconnected(ComponentName name) { // TODO Auto-generated method stub } @Override public void onServiceConnected(ComponentName name, IBinder service) { // get instance of the aidl binder mRemoteService = IRemoteService.Stub.asInterface(service); try { String message=mRemoteService.sayHello("Mina"); Log.v("message", message); } catch (RemoteException e) { Log.e("RemoteException", e.toString()); } } }; }</pre></div>and that's was all about calling remote services with AIDL.

In this post we will see how can a client application call the methods of a service defined in another application. this is achieved through...

Official Google Blog: When patents attack Android

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Infographic by Android Developers at [x]cubelabs

Symbyo Technologies: The Android Invasion Continues!!

Android Services

<div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"> </div>Android Service is used for long-running processes that do not require user interaction, such as calling a web service and parsing response. Or processes that need to be running even if the application that started the service is not on the foreground such as playing mp3 files in a music player. we need to distinguish between A Service and a Thread or an AsyncTask: Threads or Async task perform their tasks in a background thread thus they do not block the main thread, while a service performs it's work in the main thread. so if a service is performing an intensive task such as calling a web service, it may block the main thread until it finishes. So for intensive tasks a service should run it's work in a background thread. A service runs in the same process of the application and keeps running until stopped by itself, stopped by the user or killed by the system if it needs memory. <h2>Creating a service:</h2>to create a service we create a class that extends android.app.Service and it would be like this: <pre class="brush:java">public class DemoService extends Service { @Override public IBinder onBind(Intent arg0) { // TODO Auto-generated method stub return null; } }</pre>next we need to define our service in our AndroidManifest.xml file: <pre class="brush:xml"><service android:name="DemoService"></service></pre>The service life cycle has the following events <ul><li>onCreate(): called when the service is created.</li><li>onStart(): Called when the service starts by a call to startService(Intent intent).</li><li>onDestroy(): Called as the service is terminates.</li></ul><h2>Calling a service:</h2>A service can be called from an activity in two ways: <ol><li>By calling startService(Intent intent).</li><li>By binding to the service through an Binder object.</li></ol><h3>calling startService(Intent intent):</h3>to start a service from an activity using this method, we create an intent and start the service like this: <pre class="brush:java">Intent intent=new Intent(this,DemoService.class); startService(intent);</pre>the startService(intent) method causes the onStart() method of the service to be called, so the service can execute it's work like this: <pre class="brush:java">public class DemoService extends Service { @Override public IBinder onBind(Intent arg0) { // TODO Auto-generated method stub return null; } @Override public void onStart(Intent intent, int startId) { super.onStart(intent, startId); doSomething(); } public void doSomething(){ // do some work } }</pre>the service will keep running until it stops itself via stop stopSelf() after finishing work: <pre class="brush:java">@Override public void onStart(Intent intent, int startId) { super.onStart(intent, startId); doSomething(); stopSelf(); }</pre>or it can be stopped from the activity via stopService(Intent intent). <h3>Binding to a service through an Binder object:</h3>As the service runs in the same process of the application the service has only one instance (singleton) instance running. you may want to keep reference to this instance to perform periodical tasks or to call the service methods themselves. to make the service bind-able we extends Binder class and return an instance of it in the service's onBind(Intent intent) method: <pre class="brush:java">public class DemoService extends Service { private final IBinder binder = new LocalBinder(); @Override public IBinder onBind(Intent arg0) { return binder; } public class LocalBinder extends Binder { DemoService getService() { return DemoService.this; } } @Override public void onStart(Intent intent, int startId) { super.onStart(intent, startId); doSomething(); stopSelf(); } public void doSomething(){ // do something } }</pre>then we bind the service from our activity by first creating a ServiceConnection object to handle the service connection/disconnection then binding to the service by an intent like this: <pre class="brush:java">public class MainActivity extends Activity { DemoService mService; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } ServiceConnection serviceConn=new ServiceConnection() { /** * service unbound, release from memory **/ @Override public void onServiceDisconnected(ComponentName name) { mService=null; } /** * service is bound, start it's work **/ @Override public void onServiceConnected(ComponentName name, IBinder service) { mService=((LocalBinder)service).getService(); mService.doSomething(); } }; @Override protected void onResume() { super.onResume(); // bind to the service by an intent Intent intent=new Intent(this,DemoService.class); // AUTO CREATE: creates the service and gives it an importance so that it won't be killed // unless any process bound to it (our activity in this case) is killed to bindService(intent, serviceConn, Context.BIND_AUTO_CREATE); } @Override protected void onDestroy() { super.onDestroy(); / unbind the service whena ctivity is destroyed unbindService(serviceConn); } }</pre>notice that we unbind the service in the activity's onDestroy() method to disconnect from the service and stop it from executing any further and that's was all about Android services, stay tuned for another Android tutorial.</div>

Android Service is used for long-running processes that do not require user interaction, such as calling a web service and parsing response....

Parsing JSON respone:

<div dir="ltr" style="text-align: left;" trbidi="on"> </div>if we have a JSON web service response like this: <pre>"persons" [ { "person"{ "firstName": "John", "lastName": "Smith", "age": 25 } } { "person"{ "firstName": "Catherine", "lastName": "Jones", "age": 35 } } ]</pre>this response is a JSON Array with the name "persons", this array consists of "person" JSON Objects. to parse such a reponse: <pre class="brush:java">public ArrayList<Person> getMessage(String response){ JSONObject jsonResponse; ArrayList<Person> arrPersons=new ArrayList<Person>; try { // obtain the reponse jsonResponse = new JSONObject(response); // get the array JSONArray persons=jsonResponse.optJSONArray("persons"); // iterate over the array and retrieve single person instances for(int i=0;i<persons.length();i++){ // get person object JSONObject person=persons.getJSONObject(i); // get first name String firstname=person.optString("firstname"); // get last name String lastname=person.optString("lastname"); // get the age int age=person.optInt("age"); // construct the object and add it to the arraylist Person p=new Person(); p.firstName=firstname; p.lastName=lastname; p.age=age; arrPersons.add(p); } } catch (JSONException e) { e.printStackTrace(); } return arrPersons; }</pre> notice that we used the methods optJSONArray,optString,optInt instead of using getString,getInt because the opt methods return empty strings or zero integers if no elements are found. while the get methods throw an exception if the element is not found.

if we have a JSON web service response like this: "persons" [ { "person"{ "firstName": "John", ...

Parsing XML wit SAX parser

<div dir="ltr" style="text-align: left;" trbidi="on">Android provides org.xml.sax package that has that provides the event-driven SAX parser. to parse the previous response with SAX parser, we have to create a class extending DefaultHandler and override the following methods: <ol><li>startDocument(): invoked when the xml document is open, there we can initialize any member variables.</li><li>startElement(String uri, String localName, String qName, Attributes attributes): invoked when the parser encounters a xml node, here we can initialize specific instances of our person object.</li><li>endElement(String uri, String localName, String Name): invoked when the parser reaches the closing of a xml tag. here the element value would have been completely read.</li><li>characters(char[] ch, int start, int length): this method is called when the parser reads characters of a node value.</li></ol>we want to parse this xml response: <pre class="brush:xml"><?xml version="1.0"?> <person> <firstname>Jack</firstname> <lastname>smith</lastname> <age>28</age> </person></pre>so our parsing class will be like this: <pre class="brush:java">/** * SAX parser to parse persons response */ public class PersonParser extends DefaultHandler { // arraylist to store person objects ArrayList persons; // temporary person object Person tempPerson; // string builder acts as a buffer StringBuilder builder; /** * Initialize the arraylist * @throws SAXException */ @Override public void startDocument() throws SAXException { pesons=new ArrayList(); } /** * Initialize the temp person object which will hold the parsed in//fo * and the string builder that will store the read characters * @param uri * @param localName * @param qName * @param attributes * @throws SAXException */ @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if(localName.equalsIgnoreCase.equals("person")){ tempPerson=new Person(); builder=new StringBuilder(); } } /** * Finished reading the person tag, add it to arraylist * @param uri * @param localName * @param qName * @throws SAXException */ @Override public void endElement(String uri, String localName, String qName) throws SAXException { // finished reading a person, add it to the arraylist if(localName.toLowerCase().equals("person")) { this.persons.add(tempPerson); } // finished reading "firstname" tag assign it to the temp person else if(localName.toLowerCase().equals("firstname")){ tempPerson.firstName=builder.toString(); } // finished reading "lastname" tag assign it to the temp person else if(localName.toLowerCase().equals("lastname")){ tempPerson.lastName=builder.toString(); } // finished reading "age" tag assign it to the temp person else if(localName.toLowerCase().equals("age")){ tempPerson.age=Integer.parseInt(builder.toString()); } } /** * Read the value of each tag * @param ch * @param start * @param length * @throws SAXException */ @Override public void characters(char[] ch, int start, int length) throws SAXException { // read the characters and append them to the buffer String tempString=new String(ch, start, length); builder.append(tempString); } }</pre>the code is pretty easy, the parser iterates over each node, you check the current node name and take an action. then we call the parser like this: <pre class="brush:java">public ArrayList getPersons(final String response) throws ParserConfigurationException, SAXException, IOException { BufferedReader br=new BufferedReader(new StringReader(response)); InputSource is=new InputSource(br); PersonParser parser=new PersonParser(); SAXParserFactory factory=SAXParserFactory.newInstance(); SAXParser sp=factory.newSAXParser(); XMLReader reader=sp.getXMLReader(); reader.setContentHandler(parser); reader.parse(is); ArrayList persons=parser.persons; return persons; }</pre></div>

Android provides org.xml.sax package that has that provides the event-driven SAX parser. to parse the previous response with SAX parser, we...

Parsing XML wit DOM parser

<div dir="ltr" style="text-align: left;" trbidi="on"><div dir="ltr" style="text-align: left;" trbidi="on"> </div>Android offers three types of XML parsers: <ol><li>DOM Parser.</li><li>Pull Parser.</li><li>SAX Parser.</li></ol>we'll demonstrate each using the following xml example: <pre class="brush:xml"><?xml version="1.0"?> <person> <firstname>Jack</firstname> <lastname>smith</lastname> <age>28</age> </person></pre>which we need to parse to create an object from Person class: <pre class="brush:java">public class Person{ public String firstName; public String lastName; public int age; }</pre>Parsing the response with DOM Parser:</div>Android provides org.w3c.dom library that contains classes used to parse xml by constructing a document and matching each node to parse the info. to parse our example response with DOM parser, we implement a function like this <pre class="brush:java">void parseByDOM(String response) throws ParserConfigurationException, SAXException, IOException{ Person person=new Person(); DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); Document doc = db.parse(new InputSource(new StringReader(response))); // normalize the document doc.getDocumentElement().normalize(); // get the root node NodeList nodeList = doc.getElementsByTagName("person"); Node node=nodeList.item(0); // the node has three child nodes for (int i = 0; i < node.getChildNodes().getLength(); i++) { Node temp=node.getChildNodes().item(i); if(temp.getNodeName().equalsIgnoreCase("firstname")){ person.firstName=temp.getTextContent(); } else if(temp.getNodeName().equalsIgnoreCase("lastname")){ person.lastName=temp.getTextContent(); } else if(temp.getNodeName().equalsIgnoreCase("age")){ person.age=Integer.parseInt(temp.getTextContent()); } } Log.e("person", person.firstName+ " "+person.lastName+" "+String.valueOf(person.age)); }</pre>The previous method is good, it retrieves the info correctly, but it requires that you are familiar with the xml structure so that you know the order of each xml node.

Android offers three types of XML parsers: DOM Parser. Pull Parser. SAX Parser. we'll demonstrate each using the following xml example: ...

RapidFire

<div dir="ltr" style="text-align: left;" trbidi="on"><div class="separator" style="clear: both; text-align: center;"><a href="https://market.android.com/details?id=com.peapple.rapidfire" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="82" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/android_market.png" width="207" /></a></div> <table cellpadding="0"><tbody><tr> <td> APPLICATION: RapidFire.</td><td rowspan="6"> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/rapid_fire_small_logo.png" /></td> <td rowspan="6"> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/peaapple.png" /></td> </tr><tr> <td> DEVELOPER: <a href="http://peapple.com/peapple/Peapple.html">Peapple Ltd</a></td> </tr><tr> <td> CATEGORY: Social</td> </tr><tr> <td> PRICE: Free.</td> </tr><tr> <td> REQUIRES ANDROID: 2.2 and up</td> </tr><tr> <td> CONTENT RATING: Low Maturity</td> </tr></tbody></table> With RapidFire share your messages and upload multiple photos to multiple social networks including: <table cellpadding="5"><tbody><tr> <td style="color: #666666; font-size: 14px; font-weight: bold;"> Facebook</td> <td style="color: #666666; font-size: 14px; font-weight: bold;"> Twitter</td> <td style="color: #666666; font-size: 14px; font-weight: bold;"> LinkedIn</td> <td style="color: #666666; font-size: 14px; font-weight: bold;"> WordPress</td> <td style="color: #666666; font-size: 14px; font-weight: bold;"> last.fm</td> <td style="color: #666666; font-size: 14px; font-weight: bold;"> My Space</td><td style="color: #666666; font-size: 14px; font-weight: bold;"> Tumblr</td> </tr><tr> <td> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/facebook_logo.png" /></td> <td> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/twitter_logo.png" /></td> <td> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/linkedin_logo.png" /></td> <td> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/wordpress_logo.png" /></td> <td> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/lastfm_logo.png" /></td> <td> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/myspace_logo.png" /></td> <td> <img border="0" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/tumblr_logo.png" /></td> </tr></tbody></table> now with RapidFire share your thoughts with the whole world with the whole world with a single click: <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/message_landscape_activity.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="213" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/message_landscape_activity.jpg" width="320" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">share thoughts in one click</td></tr></tbody></table>just write what you want and Fire... you can send more than 140 characters to all networks including Twitter. Sign in with your account to 11 social networks: <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/networks_activity.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/networks_activity.jpg" width="192" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;">RapidFire social networks</td></tr></tbody></table> RapidFire supports the following networks and blogs: <ol style="text-align: left;"><li>Facebook.</li><li>Twitter.</li><li>LinkedIn.</li><li>Tumblr.</li><li>My Space.</li><li>Google Buzz.</li><li>WordPress.</li><li>last. fm.</li><li>Foursquare.</li><li>Friendfeed.</li><li>idetni.ca.</li></ol><div>Take photos and include them with your message instantly:</div><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/images_service_activity.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/images_service_activity.png" width="192" /></a></div><div> </div><div>RapidFire supports the following image services:</div><div><ol style="text-align: left;"><li>YFrog.</li><li>Mobypicture.</li></ol><div>Say what you want even from your home screen:</div></div><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/rapid_fire_home_screen_widget.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/rapid_fire_home_screen_widget.jpg" width="192" /></a></div><div> share your thoughts even from your phone's home screen. Upgrade to the Pro version and enjoy more features: <div class="separator" style="clear: both; text-align: center;"><a href="https://market.android.com/details?id=com.peapple.rapidfire.pro" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="200" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/rapid_fire_pro_logo.png" width="200" /></a></div><div class="separator" style="clear: both; text-align: center;"> </div> Geo-tagging: link your posts with your locations: <div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/location_activity.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/location_activity.png" width="192" /></a></div> Ad-free: <div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/tumblr_activity.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/Rapid%20Fire/tumblr_activity.jpg" width="192" /></a></div> And a last word for developers: RapidFire is an excellent example of the application that can wrap many different APIs and provide an easy way to access them seamlessly. in such a case that you have multiple social networks APIs, it's important to isolate the user from the complications of each one through such an abstraction.</div></div>

APPLICATION: RapidFire. DEVELOPER: Peapple Ltd CATEGORY: Social PRICE: Free. REQUIRES ANDROID: 2.2 ...

Android Developers Blog: New Editing Features in Eclipse plug-in for Android

Connecting to a web service over a Secure Sockets Layer (SSL): protocol:

<div dir="ltr" style="text-align: left;" trbidi="on">Android default HttpClinet does not support SSL connections, so if you have a secured web service, you need to connect to it via javax.net.ssl.HttpsURLConnection. if you want to call a SSL SOAP web service: <pre class="brush:java">String CallWebService(String url, String soapAction, String envelope) throws IOException { URL address=new URL(url); URLConnection connection=address.openConnection(); HttpsURLConnection post=(HttpsURLConnection)connection; post.setDoInput(true); post.setDoOutput(true); post.setRequestMethod("POST"); post.setRequestProperty("SOAPAction", soapAction); post.setRequestProperty( "Content-type", "text/xml; charset=utf-8" ); post.setRequestProperty( "Content-Length", String.valueOf(envelope.length())); post.setReadTimeout(4000); OutputStream outStream=post.getOutputStream(); Writer out=new OutputStreamWriter(outStream); out.write(envelope); out.flush(); out.close(); InputStream inStream = post.getInputStream(); BufferedInputStream in = new BufferedInputStream(inStream,4); StringBuffer buffer=new StringBuffer(); // read 4 bytes a time byte[] buffArray=new byte[4]; int c=0; while((c=in.read(buffArray))!=-1){ for(int i=0;i<c;i++) buffer.append((char)buffArray[i]); } return buffer.toString(); } </pre></div>

Android default HttpClinet does not support SSL connections, so if you have a secured web service, you need to connect to it via javax.net....

Calling SOAP Web Services with Android APIs

One of the most common functionalities required in mobile applications is to call a web service to retrieve data. This process involves requ...

Calling REST Web Services with Android.

<div dir="ltr" style="text-align: left;" trbidi="on">Requesting REST web service:   you request REST web services by calling a URL with the parameters. like this <pre>http://example.com/resources/getitems</pre> an example of calling a REST web service: <pre class="brush:java">String callWebErvice(String serviceURL){ // http get client HttpClient client=new DefaultHttpClient(); HttpGet getRequest=new HttpGet(); try { // construct a URI object getRequest.setURI(new URI(serviceURL)); } catch (URISyntaxException e) { Log.e("URISyntaxException", e.toString()); } // buffer reader to read the response BufferedReader in=null; // the service response HttpResponse response=null; try { // execute the request response = client.execute(getRequest); } catch (ClientProtocolException e) { Log.e("ClientProtocolException", e.toString()); } catch (IOException e) { Log.e("IO exception", e.toString()); } try { in=new BufferedReader(new InputStreamReader(response.getEntity().getContent())); } catch (IllegalStateException e) { Log.e("IllegalStateException", e.toString()); } catch (IOException e) { Log.e("IO exception", e.toString()); } StringBuffer buff=new StringBuffer(""); String line=""; try { while((line=in.readLine())!=null) { buff.append(line); } } catch (IOException e) { Log.e("IO exception", e.toString()); return e.getMessage(); } try { in.close(); } catch (IOException e) { Log.e("IO exception", e.toString()); } // response, need to be parsed return buff.toString(); } </pre></div>

Requesting REST web service: you request REST web services by calling a URL with the parameters. like this http://example.com/resources/g...

Official Google Blog: Coming soon: make your phone your wallet

Using Android Preferences

<div dir="ltr" style="text-align: left;" trbidi="on">We saw before that we can persist an application's data using SQLite database. Android offers another way to store user's data through using preferences. Android preferences is a key/value entries that store data that can be specific to a certain activity or shared among all activities within the application. the data are stored in a xml file. Saving Preferences We can save preferences in three ways: <ol style="text-align: left;"><li>Preferences can be retrieved only by a single activity.</li><li>Preferences can be shared and retrieved among all activities within the application.</li><li>Preferences can be shared and retrieved through all applications on the device.</li></ol><div>Saving Activity-level preferences:</div>to save preferences that are accessed only from a single activity, we do it like this: <pre class="brush:java">SharedPreferences prefs=getPreferences(Context.MODE_PRIVATE); SharedPreferences.Editor editor=prefs.edit(); editor.putString("pref 1", "some text"); editor.commit(); </pre> we get a SharedPreferences object by calling getPreferences(int mode) method which takes an integer value as a parameter, the mode value can be one of the following: <ol style="text-align: left;"><li>Context.MODE_PRIVATE (0): a file creating mode that makes the created file only accessible by applications with the same user ID (access the file from the same application context, will desctribe later).</li><li>Context.MODE_WORLD_READABLE (1): file mode makes the file readable from other applications.</li><li>Context.MODE_WORLD_WRITEABLE (2): file mode allows other applications to write to the file.</li></ol><div>then we get an instance of SharedPreferences.Editor and write the preference value with editor.putString(String key, String value) method. shared preferences allows you to insert preferences using the following methods: <ol style="text-align: left;"><li>editor.putBoolean(String key, boolean value).</li><li>editor.putFloat(String key,float value).</li><li>editor.putInt(String key, int value).</li><li>editor.putLong(String key, long value)</li><li>editor.putString(String key, String value)</li></ol><div>then we call edit.commit() to save the preferences to the file. commit returns a boolean indicating the result of saving, true if successful and false if failed.</div><div> </div><div>Reading preferences values:</div>To read preferences values: <pre class="brush:java">SharedPreferences prefs=getPreferences(Context.MODE_PRIVATE); String val=prefs.getString("pref 1", "some text"); </pre>we use sharedpreferences.getString(String key, String defaultValue) (or get boolean/float/int) to return the value stored with a specific key or defaultValue if not found. Saving Application-level preferences: to save preferences that can be retrieved from all activities in the application we do it like this: <pre class="brush:java">SharedPreferences prefs= getSharedPreferences("demopref", Context.MODE_WORLD_READABLE); SharedPreferences.Editor editor=prefs.edit(); editor.putString("demostring", "hello"); editor.commit(); </pre> same as the code above, but the difference is that we give our preferences file a name (demopref in this case) so that other activities can reference that preferences file. Sharing preferences across applications: We can store preferences in one application and read them in another application, this is done reading the preferences file by loading them through the first application's context. let's assume we have two applications: <ol style="text-align: left;"><li>Application 1 with package name "com.mina.prefdemo".</li><li>Application2 with package name "com.mina.demoapp".</li></ol><div>If application1 creates a preferences file with the name "demopref" and inserts a String preference with the key/value "demostring/hello".</div><div> </div><div>now we access this file and value from application 2 like this: <pre class="brush:java">Context con; try { con = createPackageContext("com.minasamy.prefdemo", 0); SharedPreferences pref=con.getSharedPreferences("demopref", Context.MODE_PRIVATE); String x=pref.getString("demostring", "not found"); txt.setText(x); } catch (NameNotFoundException e) { Log.e(Tag, e.toString()); } </pre> Creating Preferences Activities: android provides another nice way of presenting and saving preferences. you can create Activities that extend PreferenceActivity. PreferenceActivity is an activity that displays a set of built-in preferences related widgets that are defined in xml file. the preference activity can be divided to several PreferenceCategory each containing a set of related preferences. The preferences widgets that Android provide are: <ol style="text-align: left;"><li>CheckBoxPreference: displays a check box widget.</li><li>EditTextPreference: displays an EditText widget to save user prefs.</li><li>RingtonePreference: displays a list with the  ringtones on the device.</li><li>ListPreference: displays a list of key/value items.</li></ol><div>each one of these preferences widgets is associated with a preference key. it's value is persisted instantly as the widget selection changes.</div><div> </div><div>we can construct our preferences screen xml (saved in res/xml directory) layout like this: <pre class="brush:xml"><?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> <PreferenceCategory android:title="Catogory one" android:summary="sample summary"> <CheckBoxPreference android:title="Enable" android:key="pref_enable" android:summary="enables a preference"/> <EditTextPreference android:summary="Edit text prefrence" android:title="Edit" android:key="pref_edit"/> </PreferenceCategory> <PreferenceCategory android:title="Category2" android:summary="sample summary"> <RingtonePreference android:key="pref_ring" android:title="Ringtones preference"/> <ListPreference android:key="pref_list" android:title="List Preference" android:dialogTitle="List Pref Dialog" android:entries="@array/pref_items" android:entryValues="@array/pref_items_values"/> </PreferenceCategory> </pre> then from our activity: <pre class="brush:java">public class PrefActivity extends PreferenceActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); addPreferencesFromResource(R.xml.prefs); } } </pre> and the activity will look like this: <div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs1.png" width="213" /></a></div><div class="separator" style="clear: both; text-align: center;"> </div><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs2.png" width="213" /></a></div><div class="separator" style="clear: both; text-align: center;"> </div><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs3.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs3.png" width="213" /></a></div><div class="separator" style="clear: both; text-align: center;"> </div><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs4.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2011/May/prefs/prefs4.png" width="213" /></a></div><div class="separator" style="clear: both; text-align: center;"> </div><div class="separator" style="clear: both; text-align: center;"> </div>the ListPreference can be associated with String array resources as it's key/value entries <pre class="brush:xml"><string-array name="pref_items"> <item>Item1</item> <item>Item2</item> <item>Item3</item> <item>Item4</item> <item>Item5</item> </string-array> <string-array name="pref_items_values"> <item>1</item> <item>2</item> <item>3</item> <item>4</item> <item>5</item> </string-array> </pre> to reference the preference widgets programmatically: <pre class="brush:java">EditTextPreference pref_edit=(EditTextPreference)findPreference("pref_edit"); </pre></div></div></div></div>

We saw before that we can persist an application's data using SQLite database. Android offers another way to store user's data throu...

The Difference between Handler and AsyncTask

<div dir="ltr" style="text-align: left;" trbidi="on"> After we saw both Handlers and AsyncTasks a question may evolve: what's the difference between the two and when to use one of them over the other ? The Handler is associated with the application's main thread. it handles and schedules messages and runnables sent from background threads to the app main thread. AsyncTask provides a simple method to handle background threads in order to update the UI without blocking it by time consuming operations. The answer is that both can be used to update the UI from background threads, the difference would be in your execution scenario. You may consider using handler it you want to post delayed messages or send messages to the MessageQueue in a specific order. You may consider using AsyncTask if you want to exchange parameters (thus updating UI) between the app main thread and background thread in an easy convinient way. </div>

After we saw both Handlers and AsyncTasks a question may evolve: what's the difference between the two and when to use one of them over ...

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