Impetus Technologies Interview Questions and Answers

Explains the working of hashmap and the difference between abstract class and interface.

• Hashmap is a data structure that stores key-value pairs and uses hashing to retrieve values quickly.

• Abstract classes are classes that cannot be instantiated and can have both abstract and non-abstract methods.

• Interfaces are contracts that define a set of methods that a class must implement.

• Using interfaces is better than abstract cl...read more

Questions related to Java programming language and memory management.

• Overriding is a concept where a subclass provides its own implementation of a method that is already present in its superclass.

• JVM stores class information in the method area and objects in the heap area.

• Serialization is the process of converting an object into a stream of bytes to store it in a file or send it over a network.

• Thread class methods incl...read more

Reverse array in-place, find frequency of distinct elements, and implement Singleton class.

• To reverse an array in-place, swap the first and last elements, then move towards the center until the entire array is reversed.

• To find the frequency of distinct elements, use a hash table to count occurrences of each element.

• To implement a Singleton class, create a private constructor, a private static instance variable, and a p...read more

Creating XPath expressions for locating elements on a web page.

• Use // to select any element in the document

• Use / to select a direct child element

• Use [@attribute='value'] to select elements based on attribute value

Priority is the order in which defects should be fixed, severity is the impact of a defect on the system.

• Priority determines the order in which defects should be fixed, while severity determines the impact of a defect on the system.

• Priority is usually assigned based on business needs and deadlines, while severity is based on the impact on functionality.

• For example, a spelling mistake in a button label may have low seve...read more

Bug leakage refers to bugs that are not caught during testing and make their way into production.

• Bug leakage occurs when bugs are not identified and fixed during the testing phase.

• These bugs can then make their way into the production environment, causing issues for end users.

• Bug leakage can be caused by inadequate testing, miscommunication between teams, or changes made after testing.

• Examples include a critical bug in...read more

My Selenium pytest framework is a robust automation tool that utilizes the pytest testing framework for efficient and reliable testing.

• Utilizes Selenium WebDriver for interacting with web elements

• Uses pytest for test case management and execution

• Employs fixtures for setup and teardown of test environments

• Generates detailed test reports for analysis

• Supports parallel test execution for faster results

Using PySpark for group by and aggregation operations on large datasets.

• Use DataFrame API for efficient data manipulation.

• Example: df.groupBy('column_name').agg({'other_column': 'sum'}) to sum values.

• You can use multiple aggregations: df.groupBy('column_name').agg({'col1': 'avg', 'col2': 'count'}).

• Use .agg() to apply multiple aggregation functions at once.

• Consider using .withColumn() to create new columns before aggreg...read more

I have extensive experience in leading data migration projects from start to finish, ensuring seamless transition and minimal disruption.

• Led a team in migrating legacy data from on-premise servers to cloud storage

• Developed data mapping strategies to ensure accurate transfer of information

• Implemented data validation processes to identify and rectify any discrepancies

• Collaborated with stakeholders to define project scope...read more

Learn how to perform aggregations in PySpark using DataFrames and SQL functions.

• Use DataFrame API for aggregations: df.groupBy('column').agg({'other_column': 'sum'})

• Example: df.groupBy('department').agg({'salary': 'avg'}).show()

• Utilize SQL functions: from pyspark.sql import functions as F

• Example: df.groupBy('category').agg(F.count('id').alias('count')).show()

• Window functions can also be used for advanced aggregations.

Check if a list is sorted and sort the list without using Python methods.

• To check if a list is sorted, iterate through the list and compare each element with the next one. If any element is greater than the next one, the list is not sorted.

• To sort the list without using Python methods, implement a sorting algorithm like bubble sort, selection sort, or insertion sort.

• Example for checking if a list is sorted: ['a', 'b', ...read more

Diff string string builder compares two strings and returns the differences.

• Use a loop to iterate through each character of the strings

• Compare characters at the same index in both strings

• Build a new string with the differing characters

Encapsulation, Inheritance, Polymorphism, Abstraction

• Encapsulation: Bundling data and methods that operate on the data into a single unit

• Inheritance: Ability of a class to inherit properties and behavior from another class

• Polymorphism: Ability to present the same interface for different data types

• Abstraction: Hiding the complex implementation details and showing only the necessary features

Delegating tasks effectively enhances team productivity and fosters growth in a software engineering environment.

• Identify team strengths: Assign tasks based on individual skills, e.g., a developer with strong front-end skills handles UI design.

• Set clear expectations: Provide detailed requirements and deadlines to avoid confusion, e.g., using project management tools.

• Encourage autonomy: Allow team members to make decisi...read more

Interface defines a contract for classes to implement, while abstract class can have both abstract and concrete methods.

• Interfaces can only have abstract methods and constants, while abstract classes can have both abstract and concrete methods.

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Interfaces are used to achieve multiple inheritance in Java, while abstract classes are use...read more

Arrays are fixed in size, while ArrayLists can dynamically resize.

• Arrays have a fixed size determined at initialization, while ArrayLists can dynamically resize.

• Arrays are faster for accessing elements, while ArrayLists are better for adding or removing elements.

• Arrays use [] syntax for accessing elements, while ArrayLists use get() and set() methods.

• Arrays can only store primitive types, while ArrayLists can store obj...read more

Use a set to remove duplicates from a string array.

• Create a set to store unique strings.

• Iterate through the array and add each string to the set.

• Convert the set back to an array to get the unique strings.

Diff method compares values of two objects while equal method compares references of two objects.

• Diff method compares values of two objects, while equal method compares references.

• Diff method is used to check if two objects are different, while equal method is used to check if two objects are the same.

• Example: obj1.diff(obj2) vs obj1.equal(obj2)

Sealed virtual static new keywords are used in C# to control inheritance and method hiding.

• Sealed keyword prevents a class from being inherited.

• Virtual keyword allows a method to be overridden in derived classes.

• Static keyword makes a member of a class accessible without creating an instance of the class.

• New keyword hides a method from the base class in the derived class.

Overloading with different return type is not allowed in Java.

• Overloading is based on method signature, not return type

• Methods with same name and different return type will result in compile-time error

• Example: int add(int a, int b) and double add(int a, int b) is not allowed

Authentication in web API is achieved by using tokens or API keys to verify the identity of users.

• Use tokens (such as JWT) to authenticate users

• Implement OAuth for secure authentication

• Utilize API keys for authentication purposes