Q1) Once installed on a device, each Android application lives in_______? a)device memory b)external memory c) security sandbox d)None of the above Ans) c Q2)Parent class of Activity? a)Object b)Context c)ActivityGroup d)ContextThemeWrapper Ans) d Q3)What are the Direct subclasses of Activity? a)AccountAuthenticatorActivity b) ActivityGroup c) ExpandableListActivity d) FragmentActivity e) ListActivity f) all the aove Ans) f Q4)What are the indirect Direct subclasses of Activity? a)LauncherActivity b)PreferenceActivity c)TabActivity d)All the above Ans) dQ5)Parent class of Service? a)Object b)Context c) ContextWrapper d)ContextThemeWrapper Ans) c Q6)What are the indirect Direct subclasses of Services? a) RecognitionService b) RemoteViewsService c)SpellCheckerService d)InputMethodService Ans) dQ7)Which component is not activated by an Intent? a)Activity b)Services c)ContentProvider d)BroadcastReceiver Ans) cQ8)When contentProvider would be activated? a)Using Intent b)Using SQLite c)Using ContentResolver d)None of the above Ans) cQ9)Which of the important device characteristics that you should consider as you design and develop your application? a)Screen size and density b)Input configurations c)Device features d)Platform Version e)All of the above Ans) eQ10)Which are the screen sizes in Android? a)small b)normal c)large d)extra large e)All of the above Ans) eQ11)Which are the screen densities in Android? a)low density b)medium density c)high density d)extra high density e)All of the above Ans) eQ12)You can shut down an activity by calling its _______ method a)onDestory() b)finishActivity() c)finish() d)None of the above Ans) cQ13)What is the difference between Activity context and Application Context? a) The Activity instance is tied to the lifecycle of an Activity. while the application instance is tied to the lifecycle of the application, b) The Activity instance is tied to the lifecycle of the application, while the application instance is tied to the lifecycle of an Activity. c) The Activity instance is tied to the lifecycle of the Activity, while the application instance is tied to the lifecycle of an application. d) None of the above Ans) aQ14)Which one is NOT related to fragment class? a)DialogFragment b)ListFragment c)PreferenceFragment d)CursorFragment Ansa)dQ15)Definition of Loader? a) loaders make it easy to asynchronously load data in an activity or fragment. b) loaders make it easy to synchronously load data in an activity or fragment. c) loaders does not make it easy to asynchronously load data in an activity or fragment. d) None of the above. Ans) aQ16)Characteristics of the Loaders? a)They are available to every Activity and Fragment. b)They provide asynchronous loading of data. c)They monitor the source of their data and deliver new results when the content changes. d)They automatically reconnect to the last loader's cursor when being recreated after a configuration change. Thus, they don't need to re-query their data. e)All of the above. Ans) eQ17)How many ways to start services? a)Started b)Bound c)a & b d)None of the above. Ans) c Q18)If your service is private to your own application and runs in the same process as the client (which is common), you should create your interface by extending the ________class? a) Messenger b) Binder c) AIDL d)None of the above Ans) bQ19)If you need your interface to work across different processes, you can create an interface for the service with a ________? a)Binder b)Messenger c)AIDL d) b or c Ans) dQ20)AsyncTask allows you to perform asynchronous work on your user interface. It performs the blocking operations in a worker thread and then publishes the results on the UI thread. a)true b)false Ans) aQ21)Layouts in android? a)Frame Layout b)Linear Layout c)Relative Layout d)Table Layout e)All of the above Ans) eQ22) Dialog classes in android? a)AlertDialog b)ProgressDialog c)DatePickerDialog d)TimePickerDialog e)All of the above Ans) eQ23)If you want share the data accross the all applications ,you should go for? a)Shared Preferences b)Internal Storage c)SQLite Databases d)content provider Ans) dQ1. What method you should override to use Android menu system? a. onCreateOptionsMenu() b. onCreateMenu() c. onMenuCreated() d. onCreateContextMenu() Answer: A Q2. What Activity method you use to retrieve a reference to anAndroid view by using the id attribute of a resource XML? a. findViewByReference(int id); b. findViewById(int id) c. retrieveResourceById(int id) d. findViewById(String id) Answer: B Q3. Which of the following is not an Android component (i.e. a point from which the system can enter your application)? a. Service b. Activity c. Layout d. Content Provider Answer: C Q4. During an Activity life-cycle, what is the first callback method invoked by the system? a. onStop() b. onStart() c. onCreate() d. onRestore() Answer: C Q5. Which configuration file holds the permission to use the internet? a. Layout file b. Property file c. Java source file d. Manifest file Answer: DQ6. What does the following line of code achieve? Intent intent = new Intent(FirstActivity.this, SecondActivity.class ); a. Creates an hidden Intent b. Creates an implicit Intent c. Create an explicit Intent d. Starts an activity. Answer: D Q7. Which of the following is NOT a valid usage for Intents? a. Activate and Activity b. Activate a Service c. Activate a Broadcast receiver d. Activate a SQLite DB Connection. Answer: D Q8. Which of the following is not a valid Android resource file name? a. mylayout.xml b. myLayout.xml c. my_layout.xml d. mylayout1.xml Answer: B Q9. Which of these is not defined as a process state? a. Non-visible b. Visible c. Foreground d. Background Answer: A Q10. What is the name of the folder that contains the R.java file? a. src b. res c. bin d. gen Answer: D Q11. What is a correct statement about an XML layout file? a. A layout PNG image file b. A file used to draw the content of an Activity c. A file that contains all application permission information d. A file that contains a single activity widget. Answer: B Q12. What does the src folder contain? a. Image and icon files b. XML resource files c. The application manifest file d. Java source code files Answer: D Q13. Which file specifies the minimum required Android SDK version your application supports? a. main.xml b. R.java c. strings.xml d. AndroidManifest.xml Answer: D Q14. What is the parent class of all Activity widgets? a. ViewGroup b. Layout c. View d. Widget Answer: C Q15.What is the name of the class used by Intent to store additional information? a. Extra b. Parcelable c. Bundle d. DataStore Answer: C
Q16. Which is not included in the Android application framework? a. WindowManager b. NotificationManager c. DialerManager d. PackageManager Answer: C Q17.What Eclipse plugin is required to develop Android application? a. J2EE b. Android Software Development Kit c. Android Development Tools d. Web Development Tools Answer: C Q18.You can create a custom view by extending class Activity. a. True b. False Answer: B Q19.Which of these files contains text values that you can use in your application? a. AndroidManifest.xml b. res/Text.xml c. res/layout/Main.xml d. res/values/strings.xml Answer: D Q20. What does the Android project folder “res/” contain? a. Java Activity classes b. Resource files c. Java source code d. Libraries Answer: B
Q21. What does this code do? Intent intent = new Intent(); intent.setAction(Intent.ACTION_VIEW); intent.setData(android.net.Uri.parse("http://www.androidatc.com")); startActivity(intent); a. Starts a sub-activity b. Starts a service c. Sends results to another activity. d. Starts an activity using an implicit intent. Answer: D Q22. Which of the following is a Java call-back method invoked when a view is clicked? a. Detector b. OnTapListener c. OnClickDetector d. OnClickListener Answer: D Q23.Which of the following is not an Activity lifecycle call-back method?a. onStart b. onCreate c. onPause d. onBackPressed Answer: D Q24.Which method is used to close an activity? a. Destroy( ) b. Finish( ) c. Stop( ) d. Close( ) Answer: B Q25. Which of the following Activity life-cycle methods is called once the activity is no longer visible? a. onStop b. onPause c. onDestroy d. onHide Answer: A
Q26. Which of the following is a correct Android Manifest statement? a. <uses-permission android:name =”android.Internet”/> b. <uses-permission android:name =”android.Internet”></uses-permission> c. <uses-permission android:name =”android.permission.Internet”> d. <uses-permission android:name =”android. permission.Internet”/> Answer: D Q27.Which of the following is true about attribute android:windowSoftInputMode of the <activity> tag in file AndroidManifest.xml? a. It specifies whether the window is in full screen or not b. It adjusts how the main window of the activity interacts with keyboard c. It adjusts how the window should be launched d. It adjusts the window orientation Answer: BQ28. Which of the following tools dumps system log messages including stack traces when the device or emulator throws an error? a. DDMS b. Logcat c. Console d. ADB Answer: B Q29. Javascript is enabled by default in a WebView a. True b. False Answer: B Q30. How to enable JavaScript in WebView? a. myWebView. setJavaScriptEnabled(true); b. myWebView.getJavaScriptSettings.setEnabled(true) c. myWebView.getSettings().setJavaScriptEnabled(true); d. Java script is always enabled in WebView Answer: CQ31.What does the following code achieve? Intent intent = new Intent(FirstActivity.this, SecondActivity.class); startActivityForResult(intent); a. Starts a browser activity b. Starts a sub-activity c. Starts an activity service d. Sends results to another activity. Answer: B Q32. When using an implicit intent, what process does the system use to know what to do with it? a. Intent resolution b. Intent declaration c. Intent overloading d. Intent transition Answer: A Q33.Which of the following is NOT true about the MenuItem interface? a. The MenuItem instance will be returned by the Menu class add(...) method. b. MenuItem can decide the Intent issued when clicking menu components. c. MenuItem can display either an icon or text. d. MenuItem can set a checkbox. Answer: BQ34. Which of the following is correct about XML layout files? a. In order to display a Ul defined in the XML layout file "main.xml", call the setContentView method of the Activity with the parameter string “main.xml". b. There is no distinction between implementation of the layout definition by code, or by XML layout file. c. In an Eclipse project using the ADT plugin, the XML layout file is found in the /res/layout directory. d. Layout information written in the XML layout file will be converted into code by the Android platform when the screen is displayed. Answer: C
Q78. Which of the following is the most "resource hungry" part of dealing with Activities on Androida. Closing an appb. Suspending an appc. Opening a new appd. Restoring the most recent appAnswer: c
Wednesday 11 April 2018
Android Objective type Questions with Answers
Wednesday 4 April 2018
Callable and Future in Java
The
need for Callable
public Object call() throws
Exception;
|
// Java program to illustrate Callable
// to return a random number
import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;
class CallableExample implements
Callable
{
public Object call() throws Exception
{
// Create
random number generator
Random
generator = new Random();
Integer
randomNumber = generator.nextInt(5);
// To
simulate a heavy computation,
// we
delay the thread for some random time
Thread.sleep(randomNumber
* 1000);
return randomNumber;
}
}
|
Future
When the call() method
completes, answer must be stored in an object known to the main thread, so that
the main thread can know about the result that the thread returned. How will
the program store and obtain this result later? For this, a Future object can
be used. Think of a Future as an object that holds the result – it may not hold
it right now, but it will do so in the future (once the Callable returns).
Thus, a Future is basically one way the main thread can keep track of the
progress and result from other threads. To implement this interface, 5 methods
have to be overridden, but as the example below uses a concrete implementation
from the library, only the important methods are listed here.
Observe that Callable and
Future do two different things – Callable is similar to Runnable, in that it
encapsulates a task that is meant to run on another thread, whereas a Future is
used to store a result obtained from a different thread. In fact, the Future
can be made to work with Runnable as well, which is something that will become
clear when Executors come into the picture.
§
public boolean cancel(boolean mayInterrupt): Used
to stop the task. It stops the task if it has not started. If it has started,
it interrupts the task only if mayInterrupt is true.
§
public Object get() throws InterruptedException,
ExecutionException: Used to get the result of the task. If the task
is complete, it returns the result immediately, otherwise it waits till the
task is complete and then returns the result.
§
public boolean isDone(): Returns true if the
task is complete and false otherwise
To create the thread, a
Runnable is required. To obtain the result, a Future is required.
The Java library has the
concrete type FutureTask, which implements Runnable and Future, combining both
functionality conveniently.
A FutureTask can be created by providing its constructor with a Callable. Then the FutureTask object is provided to the constructor of Thread to create the Thread object. Thus, indirectly, the thread is created with a Callable. For further emphasis, note that there is no way to create the thread directly with a Callable.
A FutureTask can be created by providing its constructor with a Callable. Then the FutureTask object is provided to the constructor of Thread to create the Thread object. Thus, indirectly, the thread is created with a Callable. For further emphasis, note that there is no way to create the thread directly with a Callable.
Here is the code for the
full example using Callable and FutureTask.
|
// Java program to illustrate Callable and FutureTask
// for random number generation
import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;
class CallableExample implements
Callable
{
public
Object call() throws
Exception
{
Random generator = new Random();
Integer randomNumber =
generator.nextInt(5);
Thread.sleep(randomNumber * 1000);
return randomNumber;
}
}
public class CallableFutureTest
{
public
static void main(String[]
args) throws Exception
{
// FutureTask is a concrete class
that
// implements both Runnable and
Future
FutureTask[] randomNumberTasks =
new FutureTask[5];
for
(int i
= 0; i < 5; i++)
{
Callable callable =
new CallableExample();
// Create the
FutureTask with Callable
randomNumberTasks[i] =
new FutureTask(callable);
// As it implements
Runnable, create Thread
// with FutureTask
Thread t = new Thread(randomNumberTasks[i]);
t.start();
}
for
(int i
= 0; i < 5; i++)
{
// As it implements
Future, we can call get()
System.out.println(randomNumberTasks[i].get());
// This method blocks
till the result is obtained
// The get method can
throw checked exceptions
// like when it is
interrupted. This is the reason
// for adding the
throws clause to main
}
}
}
|
Output:
4
2
3
3
0
All interaction with the
thread after it starts is using the FutureTask object as it implements the
Future interface. Hence, there is no need to store the Thread objects. Using
the FutureTask object, one can cancel the task, check if it is complete or try to
get the result.
Here is the code using only
Runnable.
|
// Java program to illustrate Runnable
// for random number generation
import java.util.Random;
import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;
class RunnableExample implements
Runnable
{
// Shared object to store result
private Object result = null;
public void
run()
{
Random
generator = new Random();
Integer
randomNumber = generator.nextInt(5);
// As run
cannot throw any Exception
try
{
Thread.sleep(randomNumber
* 1000);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
// Store
the return value in result when done
result =
randomNumber;
// Wake up
threads blocked on the get() method
synchronized(this)
{
notifyAll();
}
}
public synchronized Object get()
throws InterruptedException
{
while (result == null)
wait();
return result;
}
}
// Code is almost same as the previous example with a
// few changes made to use Runnable instead of Callable
public class RunnableTest
{
public static void
main(String[] args) throws
Exception
{
RunnableExample[]
randomNumberTasks = new RunnableExample[5];
for (int
i = 0; i < 5; i++)
{
randomNumberTasks[i]
= new RunnableExample();
Thread
t = new Thread(randomNumberTasks[i]);
t.start();
}
for (int
i = 0; i < 5; i++)
System.out.println(randomNumberTasks[i].get());
}
}
|
Sample
Output
0
4
3
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