HCL Interview Questions for Android Developer

The Singleton Design Pattern is a Creational pattern. The main objective of the singleton class is to create only one instance of a class and to provide only one global access point to that object. For instance, in Java, the Calendar class uses its own getInstance()method to get the object to be used.

Android Activity is the subclass of ContextThemeWrapper class. An activity is a single screen with a user interface just like a window or frame of the application.

A process is an active program under execution. Processes require more time for context switching as they are heavier. A program becomes a process at execution time. A process can create other processes which are known as Child Processes. The process has stated such as new, ready, running, waiting, terminated, suspended.

A thread is a lightweight process. Threads require less time for context switching as they are lighter than processes. Thread is the segment of a process. Processes can have multiple threads and these multiple threads are contained within a process. A thread has mainly 3 states such as running, ready, and blocked. The thread takes less time to terminate as compared to the process.

A broadcast receiver is an Android component. It allows registering for system or application events. Once an event happens, all receivers are notified by the Android runtime.

An "Application Not Responding" (ANR) error is triggered, When the UI thread of an Android app is blocked for too long.

Fragments are incomplete sentences. it is usually pieces of sentences that have become disconnected from the main clause. You can remove the period between the fragment and the main clause to correct them.

IntentService is a base class for Services. Services handle asynchronous requests expressed as Intents on demand.

The Service is the base class for the IntentService that uses the “work queue process” pattern where the IntentService handles the on-demand requests expressed as Intents of clients.

Orientation in Android is the view in which a device is directed.

There are 2 types of Orientation are available in Android.

• Portrait
• Landscape

Different states of activity are as follows:

• Active
• Paused
• Stopped
• Destroyed

Different data types supported by AIDL are as follows:

• String
• List
• Map
• CharSequence
• classes

Dalvik executable file which is generally known as a dex file is an optimized class file. It is running on the Dalvik virtual machine.

It has .dex extension and is zipped into a single .apk file on the device.

The Android Emulator individual simulates Android devices on a PC. It provides most of the capabilities of a true Android device. By exploiting Android individually, you'll be able to check your application on a range of devices and Android API levels without having to possess every physical device.

The context in Android is the context of the current state of the application. The context in Android is used to get information regarding the activity, application, and get access to resources, databases, and shared preferences, and etc.