200+ Developer Interview Questions and Answers

I regularly use Python in my work.

• Python is a versatile and powerful programming language.

• It is widely used for web development, data analysis, and automation.

• Python has a large and active community, making it easy to find support and resources.

• Some popular Python frameworks and libraries include Django, Flask, and NumPy.

Find element in 2D array which is max in column and min in row with minimum comparisons

• Iterate over rows and columns to find max and min elements respectively

• Compare the max element of a column with the min element of its row

• Return the element if it satisfies the condition

• Consider edge cases like multiple elements satisfying the condition

To ensure accurate estimates for a project, I follow these steps:

• Thoroughly analyze project requirements and scope

• Break down the project into smaller tasks

• Consider past project data and historical performance

• Consult with team members and stakeholders

• Use estimation techniques like bottom-up or top-down

• Factor in potential risks and uncertainties

• Regularly review and update estimates as the project progresses

Write a formula to display A if A is present, display B if B is present else display None.

• Use conditional statements to check if A or B is present

• If A is present, display A

• If B is present, display B

• If neither A nor B is present, display None

No, the 'this' keyword cannot be equal to null.

• The 'this' keyword refers to the current instance of a class.

• It is used to access the members of the current object.

• Since 'this' refers to an object, it cannot be null.

Design considerations for an elevator system with 5 elevators and 50 floors.

• Traffic patterns and peak hours should be analyzed to determine the optimal number of elevators to be in operation at any given time.

• Elevators should be programmed to prioritize stops based on the direction of travel and the proximity of the requested floor to the elevator's current location.

• The system should be designed to minimize wait times and maximize efficiency.

• Safety features such as emergency ...read more

Explanation of Java class loading and dynamic class loading.

• Java class loaders are responsible for loading classes into the JVM.

• There are three types of class loaders: bootstrap, extension, and application.

• To run a class in a package, you need to specify the fully qualified name of the class.

• Dynamic class loading allows classes to be loaded at runtime instead of compile time.

• This can be useful for plugins or modules that are not known at compile time.

C++ is a compiled language while Java is an interpreted language. Both have their own advantages and disadvantages.

• C++ is faster and more efficient than Java due to its compiled nature.

• Java is more platform-independent and has better memory management.

• C++ is commonly used for system-level programming while Java is used for web and mobile applications.

• Choosing between the two depends on the specific project requirements and goals.

Fill the 3 gallon jug, pour it into the 5 gallon jug, fill the 3 gallon jug again, pour it into the 5 gallon jug until it is full, leaving 1 gallon in the 3 gallon jug.

• Fill the 3 gallon jug

• Pour the 3 gallon jug into the 5 gallon jug

• Fill the 3 gallon jug again

• Pour the 3 gallon jug into the 5 gallon jug until it is full

• The 4 gallon jug will have 1 gallon of water

Constructor overriding is not allowed in Java to maintain the integrity of the object creation process.

• Constructor is used to initialize the object state, and allowing overriding can lead to unexpected behavior.

• Inheritance allows the subclass to inherit the superclass constructor, but not override it.

• If a subclass needs to modify the behavior of the superclass constructor, it can use constructor chaining or call a separate method.

• Example: If a subclass overrides the superclas...read more

Query to find the second highest salary in a table.

• Use the MAX() function to find the highest salary.

• Use the WHERE clause to exclude the highest salary from the result.

• Use the MAX() function again to find the second highest salary.

Normalization is used to eliminate data redundancy and improve data integrity. 3NF ensures that each attribute is dependent on the primary key.

• Normalization helps in organizing data in a structured manner

• It eliminates data redundancy and inconsistencies

• 3NF ensures that each attribute is dependent on the primary key

• For example, a table with columns like Order ID, Product ID, and Customer ID can be normalized to eliminate redundant data

Answering interview questions for a Developer position

• Sorting algorithms: code, complexity calculation, and types

• ArrayList sorting

• Abstract class vs Interface

• Explaining application architecture

• Different types of joins and their usage

• Swap logic with and without a third variable

• Client-side vs server-side validation

• Code deployment experience

• Working in sprints

Connect nodes to their right in a binary tree using an extra pointer.

• Traverse the tree using level order traversal

• For each node, connect its right child to the next node in the level

• If there is no next node, set the right child to null

No, static and public cannot be interchanged.

• Static and public are two different keywords in programming.

• Static is used to define a variable or method that belongs to the class itself, rather than an instance of the class.

• Public is an access modifier that allows the variable or method to be accessed from anywhere in the program.

• Interchanging static and public would result in a syntax error.

• For example, in Java, the following code is valid: public static int myVariable = 10;

• Bu...read more

Managing computing priorities involves prioritizing requests based on urgency, importance, and available resources.

• Assess the urgency and importance of each request

• Consider the impact on business goals and objectives

• Evaluate the available resources and capacity

• Communicate with stakeholders to understand their needs

• Establish a prioritization framework or criteria

• Regularly review and adjust priorities as needed

Inheritance is a mechanism in OOP where a new class is derived from an existing class. Overloading is having multiple methods with the same name but different parameters. Overriding is having a method in the subclass with the same name and parameters as in the superclass.

• Inheritance allows for code reuse and promotes code organization.

• Overloading is used to have multiple methods with the same name but different parameters.

• Overriding is used to change the implementation of a m...read more

Virtual functions allow polymorphism in C++. Vtable is a lookup table for virtual functions and vpointer points to it.

• Virtual functions are used to achieve runtime polymorphism

• Vtable is a table of function pointers for virtual functions

• Vpointer points to the vtable of the object

• When a virtual function is called, the vpointer is used to lookup the correct function in the vtable

• Vtable is created at compile time and is unique for each class

The most popular SDLC model is Agile.

• Agile is iterative and flexible, allowing for changes throughout the development process.

• It emphasizes collaboration and customer satisfaction.

• Other popular models include Waterfall, Spiral, and V-Model.

• Agile is commonly used in software development, but can be applied to other industries as well.

Yes, we can handle exceptions in constructor and destructor.

• In constructor, we can use try-catch block to handle exceptions.

• In destructor, we should avoid throwing exceptions as it can lead to undefined behavior.

• If an exception is thrown in constructor, the object is not fully constructed and should be destroyed.

• If an exception is thrown in destructor, it should be caught and handled properly to avoid program termination.

useMemo is used to memoize a value while useCallback is used to memoize a function.

• useMemo is used to optimize expensive computations by caching the result and returning it if the inputs are the same.

• useCallback is used to optimize expensive function creation by caching the function and returning it if the inputs are the same.

• useMemo returns a value while useCallback returns a memoized function.

• useMemo is used for memoizing values that are not functions while useCallback is u...read more

To setup a network in a lab, you need equipment and a plan.

• Determine the network topology and design

• Choose appropriate networking equipment such as routers, switches, and cables

• Configure network settings such as IP addresses and subnet masks

• Test the network to ensure connectivity and functionality

• Consider security measures such as firewalls and access control

• Examples of equipment: Cisco routers, Juniper switches, Cat6 Ethernet cables

Types of Constructors

• Default constructor: No arguments, initializes object with default values

• Parameterized constructor: Takes arguments and initializes object with provided values

• Copy constructor: Creates a new object by copying the values of an existing object

• Static constructor: Initializes static members of a class

• Private constructor: Restricts the creation of objects from outside the class

Find if an array has a majority element in O(n)

• Iterate through the array and keep track of the count of each element

• If the count of any element is greater than half the length of the array, return true

• Otherwise, return false

A program to reverse a string

• Iterate through the characters of the string from the last to the first

• Append each character to a new string

• Return the reversed string

Code to find common elements between two arrays

• Iterate through each element of the first array

• Check if the element exists in the second array

• If yes, add it to a new array or print it

Functions return a value while stored procedures do not.

• Functions can be used in SQL statements while stored procedures cannot.

• Functions can be called from within stored procedures.

• Functions can be used in views while stored procedures cannot.

• Functions can have input parameters while stored procedures can have both input and output parameters.

A linked list is a data structure that stores a sequence of elements. A doubly traversable linked list allows traversal in both directions.

• Linked list is a collection of nodes where each node contains a data field and a reference to the next node.

• Doubly traversable linked list has an additional reference to the previous node.

• Traversal can be done in both directions using the next and previous references.

• Example: Doubly linked list can be used to implement a browser's forward ...read more

Pure virtual functions are functions with no implementation in base class. Pure virtual destructor is used to ensure proper destruction of derived objects.

• Pure virtual functions are declared with the syntax virtual void functionName() = 0;

• Classes with pure virtual functions are called abstract classes and cannot be instantiated.

• Derived classes must implement pure virtual functions to be instantiated.

• Pure virtual destructors are used to ensure proper destruction of derived obj...read more

MVC is a software architecture pattern. Routing is the process of directing HTTP requests to the appropriate controller. Finally block is used to execute code after a try-catch block.

• MVC stands for Model-View-Controller

• Routing is used to map URLs to specific actions in a controller

• Finally block is used to ensure that a section of code is always executed, even if an exception is thrown

Yes

• A future method can be called from a batch class

• Future methods are used to perform long-running operations asynchronously

• Batch classes are used to process large data sets in smaller chunks

• Calling a future method from a batch class allows for parallel processing

Synchronized ensures only one thread can access a resource at a time, while concurrent allows multiple threads to access it simultaneously.

• Synchronized is used for thread safety and mutual exclusion.

• Concurrent is used for improving performance and scalability.

• Synchronized can cause performance issues due to locking.

• Concurrent can cause race conditions and requires careful synchronization.

• Examples of synchronized: synchronized methods, synchronized blocks.

• Examples of concurren...read more

Given two linked lists, check if they have a common node.

• Traverse both lists and compare each node's memory address

• Use a hash table to store memory addresses of nodes in one list and check for matches in the other list

• If one list is shorter, traverse it first and then start traversing the longer list from the difference in length

OPPS stands for Object-Oriented Programming Principles. It includes concepts like encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling of data and methods into a single unit (class) to hide implementation details.

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

• Polymorphism: Ability to use a single interface to represent different types of objects.

• Abstraction: Simplifying complex systems by breaking them down in...read more

The bot is ready to run when it has completed all necessary initialization processes.

• Check if all required dependencies have been installed

• Ensure all necessary configurations have been set up

• Verify that the bot can connect to any required APIs or databases

• Test the bot's functionality to ensure it is working as expected

Events in reports, search exits, internet windows in smartforms

• Events in reports can be triggered by user actions or system events

• Search exits allow for custom search functionality in reports

• Internet windows in smartforms can be used to display web content

• Types of internet windows include URL, HTML, and MIME

Return an array with only unique elements

• Use a Set to store unique elements

• Loop through the array and add each element to the Set

• Convert the Set back to an array and return it

Polymorphism is the ability of an object to take on many forms.

• Allows objects of different classes to be treated as if they were of the same class

• Enables flexibility and extensibility in code

• Examples include method overloading and overriding

• Used to implement inheritance and interfaces

Entity Framework is an ORM tool for .NET applications. It allows developers to work with databases using objects.

• Entity Framework is a Microsoft product

• It supports various database providers such as SQL Server, MySQL, Oracle, etc.

• It uses LINQ to query data from the database

• It supports Code First, Database First, and Model First approaches

• Recorded details can be viewed using SQL Profiler or logging frameworks like Serilog

To get more sales quickly, focus on targeted marketing, improving product quality, offering promotions, and providing exceptional customer service.

• Implement targeted marketing strategies to reach potential customers

• Enhance product quality to attract and retain customers

• Offer promotions and discounts to incentivize purchases

• Provide exceptional customer service to build loyalty and encourage repeat sales

Query to delete duplicate rows in a table

• Use GROUP BY clause to group the rows by their unique values

• Use HAVING clause to filter out the groups with count greater than 1

• Use DELETE statement to delete the duplicate rows

Code to find the difference between two dates.

• Use a date library like moment.js or date-fns

• Subtract the earlier date from the later date to get the difference

• Convert the difference to the desired format (days, hours, etc.)

Program for hashcode and equal implementation

• Override hashCode() method to generate unique hashcode for each object

• Override equals() method to compare two objects based on their attributes

• Ensure that if two objects are equal, their hashcodes should also be equal

• Use Objects.hash() method to generate hashcode for multiple attributes

• Example: public int hashCode() { return Objects.hash(attribute1, attribute2); }

• Example: public boolean equals(Object obj) { return this.attribute1 =...read more

Spring IOC is a container that manages the lifecycle of Java objects. Dependency Injection is a design pattern that allows objects to be loosely coupled.

• Spring IOC is a container that manages the creation and destruction of objects

• Dependency Injection is a design pattern that allows objects to be loosely coupled

• Spring IOC uses Dependency Injection to inject dependencies into objects

• Dependency Injection can be implemented without using Spring IOC

Arrays are fixed in size and store homogeneous data types, while collections are dynamic and store heterogeneous data types.

• Arrays are declared with a fixed size, while collections can grow or shrink dynamically.

• Arrays can only store elements of the same data type, while collections can store elements of different data types.

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

• Examples of arrays include int[], double[], and ch...read more

The most important thing while transporting vehicles in loose format is to secure them properly.

• Securing the vehicles with straps or chains to prevent them from moving during transportation

• Using appropriate padding to protect the vehicles from scratches or damage

• Ensuring that the weight of the vehicles is evenly distributed to prevent tipping or imbalance

• Following all safety regulations and guidelines for transporting vehicles

• Checking the vehicles for any pre-existing damage ...read more

Yes, we can call a future method from another future method.

• A future method can call another future method using the @future annotation.

• The second future method will be queued and executed after the first future method completes.

• It is important to note that there is a limit of 50 future method calls per Apex invocation.