Junior Developer Trainee Interview Questions and Answers

A sealed class is a class that cannot be inherited and an extension method is a method that allows adding new methods to existing types without modifying the original type.

• Sealed class restricts inheritance, preventing other classes from deriving from it.

• Extension methods allow adding new methods to existing types without modifying the original type.

• Example of sealed class: 'sealed class MyClass { }'

• Example of extension method: 'public static class StringExtensions { public s...read more

Runtime polymorphism is the ability of an object to take on multiple forms during runtime.

• It is achieved through method overriding and inheritance.

• The decision of which method to call is made at runtime based on the object's actual type.

• It allows for more flexible and dynamic code.

• Example: Animal class with different subclasses like Dog, Cat, etc. Each subclass can have its own implementation of the same method like makeSound().

Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

• Abstract class can have constructors, fields, and methods, while interface cannot have any implementation.

• A class can only extend one abstract class, but can implement multiple interfaces.

• Abstract classes are used to define common characteristics among subclasses, while interfaces are used to define a contract for classes to implement.

• Example: Abstract class - Animal...read more

Session is specific to a user's interaction with a website, while application is global to all users.

• Session stores user-specific data, while application stores data accessible to all users.

• Session is temporary and expires after a period of inactivity, while application data persists.

• Session is used for user authentication and personalization, while application data is used for global settings and configurations.

Volley is an HTTP library that makes networking for Android apps easier and faster.

• Volley library handles network requests in a background thread

• It provides request queuing and prioritization

• Supports request cancellation and retry policies

• Used for fetching data from the internet in Android apps