10+ Elango Industries Interview Questions and Answers

Checked exceptions are checked at compile-time, while unchecked exceptions are not.

• Checked exceptions are declared in the method signature or caught using try-catch blocks.

• Unchecked exceptions do not need to be declared or caught explicitly.

• Checked exceptions are typically used for recoverable errors, while unchecked exceptions are used for unrecoverable errors.

• Examples of checked exceptions include IOException and SQLException.

• Examples of unchecked exceptions include NullPoi...read more

Method overloading is having multiple methods with the same name but different parameters. Method overriding is having a method in a subclass with the same name and parameters as in the superclass.

• Method overloading is compile-time polymorphism while method overriding is runtime polymorphism.

• Method overloading is used to provide different ways of calling the same method with different parameters.

• Method overriding is used to provide a specific implementation of a method that i...read more

To create an object, define a class and instantiate it using the 'new' keyword.

• Define a class with properties and methods

• Instantiate the class using the 'new' keyword

• Access the object's properties and methods using dot notation

Inheritance is a mechanism in object-oriented programming where a new class is created by inheriting properties of an existing class.

• Inheritance allows code reuse and promotes code organization.

• The existing class is called the parent or superclass, and the new class is called the child or subclass.

• The child class inherits all the properties and methods of the parent class, and can also add new properties and methods.

• For example, a class Animal can be a parent class, and class...read more

throw is used to explicitly throw an exception in a method, while throws is used to declare the exceptions that a method may throw.

• throw is used within a method to throw an exception when a certain condition is met

• throws is used in the method signature to declare the exceptions that may be thrown by the method

• throw is followed by an exception object, while throws is followed by the exception class names separated by commas

• Example: throw new IllegalArgumentException("Invalid i...read more

Questions related to software testing concepts and techniques.

• To add elements to a hashmap, use the put() method.

• To handle a dropdown, use the Select class in Selenium.

• To select a particular value from a dropdown, use the selectByVisibleText() or selectByValue() method.

• To set up Android SDK, download and install Android Studio.

• A data provider is a method used in TestNG to provide test data.

• To perform a right click in action class, use the contextClick() method.

• To remove dupli...read more

A collection is a group of related objects or data items that can be accessed and manipulated in a unified way.

• Collections are used to store and organize data in a program.

• They can be of various types such as arrays, lists, sets, maps, etc.

• Collections provide methods to add, remove, and access elements.

• Examples include ArrayList, HashSet, TreeMap, etc.

An interface is a contract that specifies the methods and properties that a class must implement.

• An interface defines a set of methods and properties that a class must implement

• Interfaces are used to achieve abstraction and polymorphism

• Interfaces can be used to define contracts between different parts of a system

• A class can implement multiple interfaces

• Interfaces are declared using the 'interface' keyword in most programming languages

OOPs is a programming paradigm based on the concept of objects that interact with each other.

• OOPs stands for Object-Oriented Programming.

• It focuses on creating objects that have properties and methods.

• Encapsulation, Inheritance, and Polymorphism are the three main pillars of OOPs.

• Encapsulation is the process of hiding the internal details of an object from the outside world.

• Inheritance allows a class to inherit properties and methods from another class.

• Polymorphism allows obj...read more

ArrayList vs LinkedList: ArrayList uses dynamic array, LinkedList uses doubly linked list. HashMap vs HashSet: HashMap stores key-value pairs, HashSet stores unique elements.

• ArrayList is faster for accessing elements by index, LinkedList is faster for adding/removing elements in the middle.

• HashMap allows null key and values, HashSet does not allow duplicate elements.

• Example: ArrayList list = new ArrayList<>(); LinkedList linkedList = new LinkedList<>(); HashMap map = new Hash...read more

Object-oriented programming in Java allows for creating classes and objects to model real-world entities. Multithreading enables concurrent execution of multiple threads within a single process.

• Java supports OOP concepts like inheritance, encapsulation, polymorphism, and abstraction.

• Multithreading in Java allows multiple threads to run concurrently, improving performance and responsiveness.

• Example: Creating a new thread in Java - Thread thread = new Thread(() -> { // thread l...read more

String is immutable, StringBuffer is synchronized and mutable, StringBuilder is not synchronized and mutable.

• String is immutable, meaning its value cannot be changed once it is created.

• StringBuffer is synchronized, making it thread-safe, but slower than StringBuilder.

• StringBuilder is not synchronized, making it faster than StringBuffer but not thread-safe.

Collections refer to the process of gathering and organizing items or objects into a group.

• Collections can include items such as books, art, antiques, coins, stamps, etc.

• People often collect items based on personal interest, hobby, or investment purposes.

• Collections can be displayed in museums, galleries, private homes, or online platforms.

• Some famous collections include the British Museum in London, the Louvre in Paris, and the Smithsonian in Washington, D.C.

Program to reverse a string using Java

• Use StringBuilder class to reverse the string

• Convert the string to StringBuilder, call reverse() method, then convert back to string

• Alternatively, use char array and swap characters from start and end

Object-Oriented Programming (OOP) is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• OOP focuses on creating objects that interact with each other to solve a problem.

• It involves concepts like classes, objects, inheritance, polymorphism, and encapsulation.

• For example, in a banking system, a 'BankAccount' class can have objects like 'SavingsAccount' and 'CheckingAccount' that inherit propert...read more

Abstract classes can have both abstract and non-abstract methods, while interfaces can only have abstract methods.

• Abstract classes can have constructors, interfaces cannot.

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

• Interfaces are used to achieve multiple inheritance in Java.

• Abstract classes are used to provide a common base for subclasses to extend.

List is an ordered collection of elements with duplicates allowed, while Set is an unordered collection of unique elements.

• List maintains the insertion order of elements, while Set does not guarantee any specific order.

• List allows duplicate elements, while Set does not allow duplicates.

• Examples: List - [1, 2, 3, 1], Set - {1, 2, 3}