10+ Verifone Interview Questions and Answers

Create an ArrayList and add 5 numbers to it.

• Declare an ArrayList variable and initialize it

• Use the add() method to add numbers to the ArrayList

• Numbers can be of any data type (int, double, etc.)

• Example: ArrayList numbers = new ArrayList<>(); numbers.add(1);

• Make sure to import the ArrayList class

HashMap in Java is internally stored as an array of linked lists.

• HashMap uses hashing to store key-value pairs

• Each key is hashed to an index in the array

• If there are collisions, a linked list is used to store multiple values at the same index

• The default initial capacity of HashMap is 16 and load factor is 0.75

• HashMap is not thread-safe and requires synchronization for concurrent access

Implement Push Function for Queue using Array or ArrayList

• Create a function that takes an array or ArrayList and a string as input

• Add the string to the end of the array or ArrayList

• Return the updated array or ArrayList

Explanation of OOPS pillars with real-life examples

• Abstraction: Hiding implementation details, e.g. using a TV remote without knowing how it works

• Encapsulation: Grouping related data and functions, e.g. a car's engine and transmission

• Inheritance: Creating new classes from existing ones, e.g. a sports car class inheriting from a car class

• Polymorphism: Using a single interface to represent multiple classes, e.g. a shape class with different subclasses for circle, square, etc.

I implemented various features including X, Y, and Z.

• Implemented feature X which improved system performance by 20%

• Developed feature Y which allowed for real-time data analysis

• Added feature Z which improved user experience by simplifying the interface

Overloading and overriding are two concepts in object-oriented programming that allow methods to have multiple implementations.

• Overloading is when a class has multiple methods with the same name but different parameters.

• Overriding is when a subclass provides a different implementation of a method that is already defined in its superclass.

• Overloading is resolved at compile-time while overriding is resolved at runtime.

• Example of overloading: public void print(int x) and public ...read more

Print Fibonacci series

• Fibonacci series is a sequence of numbers where each number is the sum of the two preceding ones

• The first two numbers of the series are always 0 and 1

• The series can be generated using a loop or recursion

• Example: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181

Print natural numbers in spiral form using a 2D array.

• Create a 2D array with dimensions n x n.

• Initialize variables for row and column boundaries.

• Iterate through the array in a spiral pattern, filling in natural numbers.

Design SQL tables for library management system

• Create tables for books, authors, members, transactions, etc.

• Use primary and foreign keys to establish relationships between tables

• Include columns like book title, author name, member ID, due date, etc.

Test cases for automation should be selected based on criteria such as frequency of execution, complexity, and criticality.

• Select test cases that are executed frequently to save time and effort.

• Choose test cases that are complex and require multiple steps to execute.

• Prioritize test cases that cover critical functionalities or high-risk areas.

• Consider test cases that involve integration between different systems or modules.

• Include test cases that have a high probability of fai...read more

This program counts the number of repeating characters in a given string.

• Iterate through each character in the string

• Use a hash map to store the count of each character

• If a character is already present in the hash map, increment its count

• Finally, iterate through the hash map and print the characters with their counts

Print pyramid from Fibonacci sequence

• Generate Fibonacci sequence up to a certain number

• Use the Fibonacci numbers to create the pyramid structure

• Print each row of the pyramid with appropriate spacing

Test cases for automation should be selected based on their frequency of execution, complexity, and stability.

• Identify frequently executed test cases

• Select test cases with high complexity

• Choose stable test cases

• Consider test cases with high risk and impact

• Prioritize regression test cases

• Evaluate the feasibility of automating the test case

Copy a binary tree with a friend node linking to a random node.

• Create a new node for each node in the original tree

• Copy the value of the original node to the new node

• Link the new node to the corresponding node in the new tree

• Generate a random number to select a random node in the new tree

• Link the friend node of each node in the new tree to the randomly selected node

Count the number of connected 1s in a 0/1 matrix.

• Traverse the matrix and for each 1 encountered, perform a depth-first search to find all connected 1s.

• Mark the visited 1s to avoid revisiting them.

• Increment the count of areas for each new group of connected 1s found.

• Return the total count of areas.

• Consider edge cases like empty matrix, matrix with all 0s, or matrix with all 1s.

Unit testing focuses on testing individual components or units of code in isolation, while integration testing focuses on testing how those units work together.

• Unit testing is done on individual units or components of code to ensure they work correctly in isolation.

• Integration testing is done to test how those individual units work together as a whole system.

• Unit testing is typically done by developers, while integration testing is often done by QA teams.

• Examples of unit test...read more

Black-box testing is a software testing method where the internal structure or code of the application is not known to the tester.

• Tests are conducted based on the software requirements and functionality.

• Tester focuses on inputs and outputs without knowledge of how the system works internally.

• Common techniques include equivalence partitioning, boundary value analysis, and decision table testing.

• Examples: Functional testing, regression testing, acceptance testing.