Persistent Systems Senior Java Developer Interview Questions and Answers

I am a software developer with experience in various programming languages and frameworks.

• Proficient in Java, C++, and Python

• Familiar with web development using HTML, CSS, and JavaScript

• Experience with database management systems such as MySQL and MongoDB

• Strong problem-solving and analytical skills

• Worked on projects involving machine learning and artificial intelligence

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

• 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 in a subclass that is already defined in the su...read more

Switch case is used for multiple conditions while if else is used for binary conditions.

• Switch case is faster than if else for multiple conditions.

• If else can handle complex conditions while switch case cannot.

• Switch case can only compare values of the same data type.

• If else can handle null values while switch case cannot.

• Example: switch (day) { case 1: console.log('Monday'); break; case 2: console.log('Tuesday'); brea...read more

Interface and abstract class are both used for abstraction in object-oriented programming.

• An interface is a collection of abstract methods that define a contract for a class to implement.

• An abstract class is a class that cannot be instantiated and may contain abstract methods.

• Interfaces are used to achieve multiple inheritance in Java.

• Abstract classes can have non-abstract methods and instance variables.

• An example of a...read more

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

• It allows objects of different classes to be treated as if they were objects of the same class.

• It is achieved through method overriding and method overloading.

• Example: A shape class can have multiple subclasses like circle, square, etc. and all can be treated as shapes.

• Example: A method can have different implementations in different classes but with the sa...read more

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

• Inheritance allows code reusability and saves time and effort in writing new code.

• The existing class is called the parent or base class, and the new class is called the child or derived class.

• The child class inherits all the properties and methods of the parent class and can also add its ...read more

Default case in switch case statement

• Default case is executed when no other case matches the switch expression

• It is optional and can be placed anywhere in the switch statement

• It is often used to handle unexpected input or errors

• It should always be the last case in the switch statement

I am a passionate software developer with a strong background in web development and a love for problem-solving.

• Experienced in HTML, CSS, JavaScript, and various web development frameworks

• Proficient in backend development using languages like Java, Python, and Node.js

• Familiar with database management systems such as MySQL and MongoDB

• Strong problem-solving skills and ability to work well in a team environment

I tend to get overly focused on details, which can sometimes slow down my progress.

• I have a tendency to spend too much time on perfecting small details

• I sometimes struggle with prioritizing tasks due to my focus on details

• I am working on improving my time management skills to balance detail-oriented work with efficiency

Yes, I have received offers from two other companies.

• Received offers from Company A and Company B

• Currently evaluating all offers to make an informed decision

• Considering factors like company culture, growth opportunities, and compensation

I would like to join Google because of their innovative projects and work culture.

• Google is known for its cutting-edge technology and innovative projects.

• They have a strong focus on employee well-being and work-life balance.

• Google offers opportunities for career growth and development.

• The company has a diverse and inclusive work culture.

• Google is a leader in the tech industry with a global presence.

Yes, I have worked in multiple teams in various projects.

• Worked in a team of developers to create a new software application

• Collaborated with designers, testers, and project managers to meet project deadlines

• Participated in daily stand-up meetings to discuss progress and roadblocks

Yes, they are similar.

• All 8 metal balls are of the same material.

• They have the same size and weight.

• They have the same physical properties.

• They are interchangeable in any given situation.

C++ is an extension of C with object-oriented programming features.

• C++ supports classes and objects while C does not.

• C++ has better support for polymorphism and inheritance.

• C++ has a standard template library (STL) which C does not have.

• C++ allows function overloading while C does not.

• C++ has exception handling while C does not.

For loop is used for iterating over a sequence while while loop is used for iterating until a condition is met.

• For loop is used when the number of iterations is known beforehand

• While loop is used when the number of iterations is not known beforehand

• For loop is faster than while loop for iterating over a sequence

• While loop is useful for iterating until a specific condition is met

• For loop can be used with range() functio...read more

To reverse a string without using any looping and inbuilt functions, we can use recursion.

• Create a function that takes a string as input.

• If the length of the string is 0 or 1, return the string.

• Otherwise, call the function recursively with the substring starting from the second character and concatenate the first character at the end.

• Return the reversed string.

• Example: reverseString('hello') returns 'olleh'.

A priority queue can be implemented using a single queue or multiple queues.

• One approach is to use a single queue and assign priorities to elements using a separate data structure.

• Another approach is to use multiple queues, each representing a different priority level.

• For example, if there are three priority levels, three queues can be used to implement the priority queue.

An array of objects can be used to implement a heterogeneous array.

• Each element in the array can be an object that represents a different data type.

• The objects can have different properties and methods based on their respective data types.

• For example, an element can be an object representing a string with a 'value' property and a 'length' method.

Developed a web-based inventory management system for a retail company.

• Used HTML, CSS, and JavaScript for the front-end development.

• Implemented a RESTful API using Node.js and Express for the back-end.

• Utilized a MySQL database to store and manage inventory data.

• Implemented features like product search, order management, and reporting.

• Ensured data security and user authentication using encryption and JWT.

• Collaborated wi...read more

The missing rupee is not actually missing. The calculation is misleading and does not account for the total amount paid.

• The initial amount paid by each person was Rs.10, totaling Rs.30.

• The owner gave them a discount of Rs.5, so they paid Rs.25 in total.

• The broker took Rs.2, leaving them with Rs.23.

• When the broker returned Rs.1 to each person, they each received Rs.1 back, totaling Rs.3.

• So, the total amount paid by the ...read more