Android Interview Questions

Android is a stack of software for mobile devices which includes an Operating System, middleware and some key applications. The application executes within its own process and its own instance of Dalvik Virtual Machine.

Android application architecture has the following components.They are as follows −

Services − It will perform background functionalities

Intent − It will perform the inter connection between activities and the data passing mechanism

Resource Externalization − strings and graphics

Notification − light,sound,icon,notification,dialog box,and toast

Content Providers − It will share the data between applications

Activity performs actions on the screen.If you want to do any operations, we can do with activity

The Android packaging key is compressed with classes,UI's, supportive assets and manifest.All files are compressed to a single file is called APK.

It is connected to either the external world of application or internal world of application ,Such as, opening a pdf is an intent and connect to the web browser.etc.

Android Explicit intent specifies the component to be invoked from activity. In other words, we can call another activity in android by explicit intent.

Implicit Intent doesn't specifiy the component. In such case, intent provides information of available components provided by the system that is to be invoked.

Every application must have an AndroidManifest.xml file (with precisely that name) in its root directory. The manifest file presents essential information about your app to the Android system, information the system must have before it can run any of the app's code.

Android applications has written using the java(Android SDK) and C/C++(Android NDK).

ADT stands for Android development tool,This is useful to develop the applications and test the applications.

Android SDK collaborated with Android Emulator,DDMS(Dalvik Debug Monitoring Services),AAPT(Android Asset Packaging tool) and ADB(Android debug bridge)

View group is a collection of views and other child views, it is an invisible part and the base class for layouts.

The Service is like as an activity to do background functionalities without UI interaction.

A content provider component supplies data from one application to others on request. Such requests are handled by the methods of the ContentResolver class. A content provider can use different ways to store its data and the data can be stored in a database, in files, or even over a network.

Toast Notification − It will show a pop up message on the surface of the window

Status Bar Notification − It will show notifications on status bar

Dialogue Notification − It is an activity related notification.

The container holds objects,widgets,labels,fields,icons,buttons.etc.

It is acts as bridge between emulator and IDE, it executes remote shell commands to run applications on an emulator

ANR stands for application is not responding, basically it is a dialog box that appears when the application is not responding.

The Adapter is used to create child views to represent the parent view items.

Shared preferences are the simplest mechanism to store the data in XML documents.

• Linux Kernel
• Libraries
• Android Framework
• Android applications.

Intent filters are filter out the intents.

In The Layout folder, layouts are placed as XML files

We can change bitmap images in nine sections as four corners,four edges and an axis

AlertDialog, ProgressDialog,DatePickerDialog, and TimePickerDialog

InflateException,Surface.OutOfResourceException,SurfaceHolder.BadSurfaceTypeException,and WindowManager.BadTokenException

Positive, Neutral, Negative.

Shared Preferences,Internal Storage,External Storage,SQLite Databases and Network Connection

Sticky Intent is also a type of intent which allows the communication between a function and a service for example,sendStickyBroadcast() is perform the operations after completion of intent also.

Android uses Google translator to translate data from one language into another language and placed as a string while development

WebView is UI component that can display either remote web-pages or static HTML

Android uses DVM (Dalvik Virtual Machine ) rather using JVM(Java Virtual Machine), if we want, we can get access to .jar file as a library.

Android provides a Unique ID to all applications is called as Linux ID,this ID is used to track each application.

It's not truly recommended to change application name after it's deployment, if we change, it will impact on all other internal components.

JSON,XML bitmap.etc are application resources.You can injected these files to build process and can load them from the code.

Using with intent, we can launch an activity.

Intent intent = new Intent(this, MyTestActivity.class);

        startActivity(intent);

Using with Bundle, we can pass the data to sub activities.

Bundle bun = new Bundle();

        bun.putString("EMAIL", "contact@tutorials.com");

A class which can create only an object, that object can be share able to all other classes.

Fragment is a piece of activity, if you want to do turn your application 360 degrees, you can do this by fragment.

Sleep mode mean CPU will be sleeping and it doesn't accept any commands from android device except Radio interface layer and alarm.

Android is customized Linux 3.6 kernel.

Use a dynamic broadcast receiver in the activity, and send a broadcast from the service. Once the dynamic receiver is triggered update UI from that receiver.

AndroidManifest.xml

build.xml

bin/

src/

res/

assets/

App Widgets are miniature application views that can embedded in other applications (such as the Home screen) and receive periodic updates. These views has referred to as Widgets in the user interface, and you can publish one with an App Widget provider.

Using with findViewById we can find view element.

A compiled visual resource that can used as a backgrounds,banners, icons,splash screen etc.

FLAG_ACTIVITY_NEW_TASK

FLAG_ACTIVITY_CLEAR_TOP.