Top Rated Mobile Application Developer Interview Questions

Q – 1 What is localization and how to achieve?

Ans- Localization is a way of representing the products in different languages. Android is an operating system which runs in many regions, so to reach different users localization is a must. Localization in Android can be achieved by incorporating different languages in the application which you are using. To do this knowledge of Java, XML elements, Activity life-cycle and general principles of internationalization and localization are required.

Q – 2 What is APK format in Android?

Ans- APK termed as Application package file is a format that is used to distribute and install the application software for android, and middleware on the android operating system. To make an APK file, first android is compiled and then all of its parts are grouped in one file termed as package. The package consists of the entire program’s code (.dex files), resources, manifest file etc. The file is saved with .apk extension.

Q – 3 Define Sticky Intent?

Ans- Intent is basically an abstract description of an operation that has to be performed for communication. Sticky Intent is also a type of intent which allows the communication between a function and a service. For example: sendStickyBroadcast() performs send Broadcast(Intent) which stays even after the broadcast is complete. It helps in retrieving the data quickly. The message ACTION_BATTERY_CHANGED of an operating system is an example of it.

Q – 4 How you translate in Android?

Ans- Android uses Google translator to translate data from one language into another language using XAMPP. XAMPP is used to transmit the data. The steps which have to be followed are: Type the message in your language, go to the language setting, a list will be displayed there, select the language from the list to convert your text.

Q – 5 What are resource in Android?

Ans- A user defined JSON, XML, bitmap, or other file, injected into the application build process, which can later be loaded from code.

Q – 6 What is sticky intent in Android?

Ans- sendStickyBroadcast() performs a sendBroadcast(Intent) known as sticky, i.e. the Intent you are sending stays around after the broadcast is complete, so that others can quickly retrieve that data through the return value of registerReceiver(BroadcastReceiver, IntentFilter). In all other ways, this behaves the same as sendBroadcast(Intent).

Example of a sticky broadcast sent via the operating system is ACTION_BATTERY_CHANGED. When you call registerReceiver() for that action even with a null BroadcastReceiver you get the Intent that was last broadcast for that action. Hence, you can use this to find the state of the battery without necessarily registering for all future state changes in the battery.

Q – 7 Describe about the Broadcast receiver component of Android?

Ans- A Broadcast receiver comes into action only in specific situations. Suppose an Intent for which a particular broadcast receiver has been registered occurs, the broadcast receiver is triggered into action and the user gets a notification for the same. (For example: Battery low notification).

Q – 8 Describe about the Intent component of Android?

Ans- Think of Intent as a message to allow the application to request action from the other application components (like activity), for instance VIEW, CALL, PLAY etc.

Suppose, on your Facebook app, the running activity is the Newsfeed, and you want to view (in full frame) a pic your friend posted. The click action on the photo would be the View Photo Intent, and the Photo screen (which is a new activity) gets loaded on the click (as the message is communicated).

Q – 9 Describe about the activity component of Android?

Ans- Activity provides an interface for users to interact with the application and take an action; for instance: Login to a website. The different screens/windows of an application are the different activities. An application generally has multiple activities.
Activities are like the pages in a website. For instance, in a Facebook app, the login screen is one activity, and the news feeds from your friends after signing in would be another one.

Q – 10 What are the Services component of Android?

Ans- Services are components that do not have a User Interface; they run in the background. An example of Service component in Facebook app would be the friend request notifications. They would continue to run, even if you switch to another activity or application.

Q – 11 Which are the Content provider components of Android?

Ans- Content provider is a data store that enables data sharing across different applications. Content providers provide a uniform interface to access the data. An example is Call logs.

Q – 12 What are the components of Android?

Ans- The main components of Android are:

1) Activity
2) Intent
3) Service
4) Broadcast receiver
5) Content Provider

Q – 13 Explain TTL (Time to Live) and why is it required?

Ans- TTL is a value in data packet of Internet Protocol. It communicates to the network router whether or not the packet should be in the network for too long or discarded. Usually, data packets might not be transmitted to their intended destination within a stipulated period of time.

The TTL value is set by a system default value which is an 8-bit binary digit field in the header of the packet. The purpose of TTL is, it would specify certain time limit in seconds, for transmitting the packet header. When the time is exhausted, the packet would be discarded. Each router receives the subtracts count, when the packet is discarded, and when it becomes zero, the router detects the discarded packets and sends a message, Internet Control Message Protocol message back to the originating host.

Q – 14 How to select more than one option from list in android xml file?

Ans- Specify android id, layout height and width as depicted in the following example.

Q – 15 Described about the exceptions of Android?

Ans- The following are the exceptions that are supported by Android:

InflateException:

When an error conditions are occurred, this exception is thrown
Surface.OutOfResourceException: When a surface is not created or resized, this exception is thrown

SurfaceHolder.BadSurfaceTypeException:

This exception is thrown from the lockCanvas() method, when invoked on a Surface whose is SURFACE_TYPE_PUSH_BUFFERS
WindowManager.BadTokenException: This exception is thrown at the time of trying to add view an invalid WindowManager.LayoutParamstoken.

Q – 16 Tell me which dialog boxes are supported in android?

Ans- Android supports 4 dialog boxes:

AlertDialog:

An alert dialog box supports 0 to 3 buttons and a list of select able elements, including check boxes and radio buttons. Among the other dialog boxes, the most suggested dialog box is the alert dialog box.

ProgressDialog:

This dialog box displays a progress wheel or a progress bar. It is an extension of AlertDialog and supports adding buttons.

DatePickerDialog:

This dialog box is used for selecting a date by the user.

TimePickerDialog:

This dialog box is used for selecting time by the user.

Q – 17 Describe the advantages of Android?

Ans- The following are the advantages of Android:

☆ The customer will be benefited from wide range of mobile applications to choose, since the monopoly of wireless carriers like AT&T and Orange will be broken by Google Android.
☆ Features like weather details, live RSS feeds, opening screen, icon on the opening screen can be customized
☆ Innovative products like the location-aware services, location of a nearby convenience store etc., are some of the additive facilities in Android.

Q – 18 Why to use Android?

Ans- Android is useful because:

☆ It is simple and powerful SDK
☆ Licensing, Distribution or Development fee is not required
☆ Easy to Import third party Java library
☆ Supporting platforms are – Linux, Mac Os, Windows

Q – 19 Describe a real time scenario where android can be used?

Ans- Imagine a situation that you are in a country where no one understands the language you speak and you can not read or write. However, you have mobile phone with you.

With a mobile phone with android, the Google translator translates the data of one language into another language by using XMPP to transmit data. You can type the message in English and select the language which is understood by the citizens of the country in order to reach the message to the citizens.

Q – 20 Which dialog boxes are supported in android?

Ans- There are 4 dialog boxes which have been supported by Android.

These are as follows:

Alert-dialog: it supports 0 to 3 buttons with a list of select-able elements that includes check boxes and radio buttons.

1) ProgressDialog:

It displays the progress of any dialog or application. It is an extension of AlertDialog and supports adding buttons.

2) DatePickerDialog:

It is used to give provision to the user to select the date

3) TimePickerDialog:

It is used to give provision to the user to select the time

Q – 21 Explain briefly about the Android Application Architecture?

Ans- Android application architecture allows the simplification and reuse of any application. It provides a better way to publish the capabilities of the application so that any other application can make good use of those capabilities.

This architecture includes the following components:

☆ Intent to perform some operation on some activity and service
☆ Resource Externalization – such as strings and graphics
☆ Notification signaling users – light, sound, icon etc.
☆ Content Providers – sharing of data between various applications

Q – 22 What are the different Storage Methods in android?

Ans- Android provides many options for storage of persistent data. It provides the solution according to your need. The storage’s which have been provided in Android are as follows:

Shared Preferences:

Store private primitive data in key-value pairs

Internal Storage:

Store private data on the device memory.

External Storage:

Store public data on the shared external storage.

SQLite Databases:

Store structured data in a private database.

Network Connection:

Store data on the web with your own network server.

Q – 23 How does the AOSP relate to the Android Compatibility Program?

Ans- AOSP stands for Android Open-source project that maintains Android software and keep track of the new versions. It can be used for any purpose including the devices that are not compatible with other devices. It is related to the Android Compatibility Program as it defines the implementation of Android that is compatible with the third party apps.

Q – 24 What are the file features used in android?

Ans- Android is rich in file features and it provides lots of variations in them as well.

The file features are as follows:

Intent filters:

Includes bundle of information which describes a desired action.

Icons and Labels:

Includes information for small icon and a text label that can be displayed to users. These are set for an intent filter and are used to represent a component which fulfills the function advertised by the filter.

Permissions:

It is a restriction or limitation access to a part of code or data on the device. It is given as:-android.permission.CALL_EMERGENCY_NUMBERS

Libraries:

It includes the basic packages for building and developing applications.

Q – 25 How to avoid ANR status?

Ans- Android allows the system to protect the applications that are not responsive for a period of time by displaying a status called as ANR (Application not responding). Methods should use the main thread for work, as it takes long time for the main thread to complete the task.

The work should be divided and another thread named as child thread be used for executing more tasks, as it takes less time. Main thread should provide a handler for child threads to post back upon completion.

Q – 26 Are there any rules for what I can do?

Ans- Yes! Every app needs to go through an approval process. That process looks for viruses, pornography, hate speech and a few other things. We can guide you on what is likely to be approved and what is not likely to be approved.

Most applications are approved without a problem. If you are simply promoting your business, displaying products or services, gathering orders or directing users to your location you should be fine.

Q – 27 How long does it take to build an app?

Ans- Depending on the complexity and how quickly you respond to us you could have an app built in about a month.

Q – 28 Are there monthly fees to your mobile application development services?

Ans- It depends, No this is one of the great things about an app. Once it is built and in the app store your costs are done. There is no monthly fee for maintaining an app in the App Store.

Q – 29 How much does mobile application development cost?

Ans- That is a bit like asking: How much does a truck cost? The answer is that it depends on the truck. Your needs are unique and your app needs to meet only those needs. A small Toyota will cost a lot less than a huge semi tractor trailer. A tractor trailer is great if you want to haul goods across the country but dont try to take it on a Saturday night date. We help you to avoid creating too much – or too little app. This keeps costs low.

Having us create a custom smartphone app is surprisingly affordable. Many businesses find their app costs less than even a small radio or newspaper campaign. Unlike a radio campaign, the app’s usefulness does not end with the last commercial.

Once it is created an app can add to your bottom line for a very long time. Our goal is to connect your audience with your cash register no matter where they are. With a smartphone app you give your customers access to you at the exact moment their buying decision is the strongest.

Q – 30 What is the future scope of Mobile Application developers?

Ans- Future of the mobile application development is bright

Q – 31 What is the demand of Mobile Application developers?

Ans- Desktop based IT application is present but the mobile is future. All the applications that were made to work only on desk top are being ported to mobile. In the coming 10 years, desktops will be replaced completely with mobile, and then all the applications will be designed mainly for mobile.

The demand for mobile based trained engineers are increasing every year. Now after the launch of ipad by Apple, it will be even more. Therefore; the gextgen technology will be nothing else than mobile. The demand is expected to grow 70 folds in the coming 4 years.

Q – 32 What is the Mobile Application development all about?

Ans- In the last two years, a lot of innovation has come in the mobile computing world. Apple has launched very innovative mobile phone, iphone and ipad along with app store. Google launched Android in Nov 2007. Blackberry released SDK and app world. Microsoft has come up with phone 7 framework. Almost every type of mobile can be programmed using J2ME. Making applications for all these devices is Mobile application development.