40+ Capita Interview Questions and Answers

IDisposable is an interface used to release unmanaged resources.

• It is used to release unmanaged resources like file handles, database connections, etc.

• It has a single method called Dispose() which is used to release the resources.

• It is implemented by classes that use unmanaged resources and needs to be disposed of.

• Example: SqlConnection class implements IDisposable to release the database connection.

• Example: FileStream class implements IDisposable to release the file handle.

SOLID is a set of principles for object-oriented programming to make software more maintainable and scalable.

• S - Single Responsibility Principle

• O - Open/Closed Principle

• L - Liskov Substitution Principle

• I - Interface Segregation Principle

• D - Dependency Inversion Principle

• Example: Using Single Responsibility Principle to separate UI and business logic

• Example: Using Open/Closed Principle to extend functionality without modifying existing code

Exceptions in Spring Boot can be handled using @ExceptionHandler annotation and ResponseEntity class.

• Use @ExceptionHandler annotation to handle exceptions in a specific controller or globally

• Use ResponseEntity class to return a custom error message and HTTP status code

• Use try-catch block to handle exceptions in service layer

• Use @ControllerAdvice annotation to handle exceptions globally across all controllers

• Use @ResponseStatus annotation to set a default HTTP status code for ...read more

Code to find the occurrence of a character in a string.

• Iterate through the string and check each character against the target character.

• Use a loop to count the number of occurrences.

• Consider using built-in functions like count() or find().

Concatenate the values in the given integer array with comma.

• Convert the integer array to string array using Arrays.toString()

• Use String.join() method to concatenate with comma

Inheritance, abstract class, override, and interface are all concepts in object-oriented programming.

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

• Abstract classes cannot be instantiated and are used as a blueprint for other classes.

• Override is used to provide a new implementation for a method that is already defined in a parent class.

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

• All of these concepts are used to create modul...read more

PHP caching, session handling, and API token security

• PHP caching techniques include opcode caching, data caching, and query caching

• Session handling in PHP involves creating a unique session ID for each user and storing session data on the server

• To prevent token hijacking in APIs, use HTTPS, set expiration times for tokens, and use token revocation

• Other security measures include input validation, output encoding, and using secure coding practices

Dependency Injection is a design pattern that allows objects to receive dependencies rather than creating them internally.

• Dependency Injection is used to reduce tight coupling between software components.

• It allows for easier testing and maintenance of code.

• There are three types of Dependency Injection: Constructor Injection, Setter Injection, and Interface Injection.

• Frameworks like Spring and Angular provide built-in support for Dependency Injection.

No, abstract classes cannot be instantiated.

• Abstract classes are incomplete and cannot be instantiated on their own.

• They can only be used as a base class for other classes.

• Instantiation of an abstract class will result in a compile-time error.

• However, concrete classes that inherit from the abstract class can be instantiated.

Constructors and destructors are special methods used in object-oriented programming languages to initialize and destroy objects.

• Constructors are used to initialize objects when they are created.

• Destructors are used to clean up resources used by an object when it is destroyed.

• Constructors have the same name as the class and are called automatically when an object is created.

• Destructors have the same name as the class preceded by a tilde (~) and are called automatically when a...read more

Store procedures, indexes, and virtual tables are important features of MySql.

• Store procedures are pre-written code blocks that can be executed on demand.

• Indexes are used to speed up database queries by creating a quick lookup table.

• Virtual tables are temporary tables that are created on the fly and do not persist in the database.

• Examples of store procedures include creating a new user or updating a record.

• Examples of indexes include primary keys, unique keys, and full-text i...read more

Code to check if two strings are anagram or not

• An anagram is a word or phrase formed by rearranging the letters of a different word or phrase

• To check if two strings are anagram, we can sort both strings and compare them

• Alternatively, we can use a hash table to count the frequency of each character in both strings and compare the counts

Remove duplicate objects from an array of multiple objects.

• Create a new array to store unique objects

• Loop through the original array and check if the object already exists in the new array

• If not, add it to the new array

• Return the new array

We used the Model-View-Controller (MVC) design pattern in our application.

• MVC separates the application into three interconnected components: the model, the view, and the controller.

• The model represents the data and business logic of the application.

• The view displays the data to the user.

• The controller handles user input and updates the model and view accordingly.

• MVC promotes separation of concerns and modularity.

• Example: Our web application uses AngularJS as the front-end fr...read more

Serialisation is the process of converting an object into a format that can be easily stored or transmitted.

• Serialisation is used in data storage and transmission, allowing objects to be saved to a file or sent over a network.

• It is commonly used in programming languages to convert objects into a byte stream for storage or communication.

• Examples include saving an object to a file in JSON or XML format, or sending an object over a network using protocols like HTTP.

Interfaces and abstract classes are used for abstraction and defining contracts.

• Interfaces are a collection of abstract methods that define a contract for a class to implement.

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

• Interfaces can be implemented by multiple classes, while a class can only inherit from one abstract class.

• Interfaces are used for loose coupling and to achieve multiple inheritance-like behavior.

• Abst...read more

Maintain state by using a global variable or a state management system.

• Use a global variable to store the state and access it whenever needed.

• Use a state management system like Redux or MobX to manage the state.

• Avoid using local variables or closures to store state as they will be lost when the code is repeated.

• Consider using object-oriented programming principles to encapsulate state within objects.

• Use functional programming principles to avoid mutating state directly.

• Consid...read more

Full text index is a database index that allows for efficient text-based searching.

• Full text index is used to search for specific words or phrases within a large amount of text data.

• It is commonly used in search engines, document management systems, and social media platforms.

• Full text index can be created on one or more columns of a table in a database.

• It uses techniques such as stemming, stop words, and word proximity to improve search accuracy.

• Examples of databases that su...read more

Compile time polymorphism is achieved through function overloading and operator overloading, while runtime polymorphism is achieved through function overriding using virtual functions.

• Compile time polymorphism is resolved during compile time based on the number and types of arguments passed to a function.

• Runtime polymorphism is resolved during runtime based on the actual object being referred to by a base class pointer or reference.

• Compile time polymorphism is also known as s...read more

Java program to reverse a given string using StringBuilder

• Create a StringBuilder object with the given string

• Use the reverse() method of StringBuilder to reverse the string

• Convert the reversed StringBuilder object back to a string

PHP 7 is faster, more secure and has new features compared to PHP 5.

• PHP 7 has improved performance with up to 2x faster execution

• PHP 7 has better error handling and type declarations

• PHP 7 has new operators and functions like spaceship operator and null coalescing operator

• PHP 7 has removed deprecated features like mysql extension

• PHP 7 has improved support for Unicode

• PHP 7 requires 64-bit architecture

• PHP 7 has improved memory usage

• PHP 7 has improved support for anonymous classe...read more

HTML5 is the latest version of HTML with new features and improvements.

• HTML5 supports new elements like <header>, <footer>, <nav>, <article>, <section> etc.

• HTML5 introduces new APIs like Geolocation API, Drag and Drop API, Canvas API, Web Storage API, etc.

• HTML5 supports multimedia elements like <audio> and <video> without the need for plugins.

• HTML5 has improved semantics, accessibility, and performance compared to HTML.

• HTML5 supports offline web applications through the use o...read more

SQL is a programming language used for managing and manipulating relational databases.

• SQL stands for Structured Query Language.

• It is used to communicate with and manipulate databases.

• SQL can be used to retrieve data, update data, insert data, and delete data from databases.

• Common SQL commands include SELECT, INSERT, UPDATE, DELETE.

• Examples of SQL database systems include MySQL, PostgreSQL, Oracle, SQL Server.

Count occurrences of characters in a string

• Iterate through the string and use a hashmap to store character counts

• Handle both uppercase and lowercase characters separately

• Consider using ASCII values for efficient counting

Java is a high-level programming language known for its portability, security, and object-oriented features.

• Java is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM).

• It is object-oriented, allowing for the creation of reusable code through classes and objects.

• Java is known for its security features, such as sandboxing and encryption.

• It supports multithreading, allowing for concurrent execution of multiple tasks.

• Java has a rich standard l...read more

Quick sort is a sorting algorithm that uses divide and conquer approach to sort an array or list.

• It selects a pivot element and partitions the other elements into two sub-arrays, according to whether they are less than or greater than the pivot.

• It then recursively sorts the sub-arrays.

• It is a very efficient sorting algorithm with an average time complexity of O(n log n).

James Gosling, Mike Sheridan, and Patrick Naughton invented the Java language.

• Invented by James Gosling, Mike Sheridan, and Patrick Naughton at Sun Microsystems in the early 1990s.

• Java was originally developed to be used in consumer electronic devices like set-top boxes.

• Released in 1995 as a core component of Sun Microsystems' Java platform.

• Known for its platform independence, allowing code to run on any device that has a Java Virtual Machine (JVM).

Different keys in SQL include primary key, foreign key, unique key, and composite key.

• Primary key uniquely identifies each record in a table

• Foreign key establishes a relationship between two tables

• Unique key ensures that all values in a column are unique

• Composite key is a combination of multiple columns to uniquely identify a record

Function is a reusable block of code that returns a value, while stored procedure is a group of SQL statements that can be executed together.

• Functions return a single value, while stored procedures can return multiple values.

• Functions are called in SQL queries, while stored procedures are called using EXECUTE statement.

• Functions cannot modify database state, while stored procedures can.

• Functions are easier to test and debug compared to stored procedures.

• Example: Function to c...read more

A linked list is a linear data structure where each element is a separate object with a pointer to the next element.

• Consists of nodes that contain data and a pointer to the next node

• Can be singly linked or doubly linked

• Allows for efficient insertion and deletion operations

• Example: Linked list can be used to implement a stack or queue

State management is the process of managing the state of an application, including data flow, user interface updates, and user interactions.

• State management involves storing and updating the current state of an application.

• It helps in managing data flow between different components of the application.

• State management is crucial for ensuring that user interface updates reflect the most recent data.

• Examples of state management tools include Redux, MobX, and Context API in React...read more

To count the frequency of characters in a word, iterate through the word and store the count of each character in a data structure.

• Create a map or dictionary to store the count of each character

• Iterate through the word and update the count of each character in the map

• Return the map with character frequencies

Understanding flowcharts for If and Nested If scenarios in software engineering.

• Flowcharts visually represent the logic of a program using symbols and arrows.

• If statements are represented by a diamond shape with a condition inside.

• Nested If scenarios involve multiple levels of If statements within each other.

• Each branch in a flowchart represents a possible path the program can take based on conditions.

• Example: If x > 5, do A. If x < 5, do B. If y > 10, do C.

• Example: If x > 5,...read more

MVC architecture is a software design pattern that separates an application into three main components: Model, View, and Controller.

• Model represents the data and business logic of the application

• View is responsible for displaying the data to the user

• Controller acts as an intermediary between Model and View, handling user input and updating the Model accordingly

• Example: In a web application, the Model could be a database, the View could be the HTML/CSS for the user interface, ...read more

Design patterns are reusable solutions to common software problems. Android system uses various design patterns.

• MVC (Model-View-Controller) pattern is used in Android to separate UI logic from business logic.

• Singleton pattern is used to ensure only one instance of a class is created.

• Observer pattern is used to notify changes in data to multiple components.

• Builder pattern is used to simplify complex object creation.

• Adapter pattern is used to convert the interface of a class in...read more

Memory can be stored in various ways such as RAM, ROM, hard drives, and cloud storage.

• Memory can be stored in Random Access Memory (RAM) for quick access by the CPU.

• Read-Only Memory (ROM) stores permanent data that cannot be modified.

• Hard drives store data magnetically on spinning disks or solid-state drives.

• Cloud storage allows data to be stored remotely on servers accessed over the internet.

A unique key is a field or combination of fields in a database table that uniquely identifies each record in the table.

• A unique key ensures that no two records in a table have the same values for the specified key fields.

• It can be a single field or a combination of multiple fields.

• Unique keys are used to enforce data integrity and prevent duplicate entries.

Collections are classes that group similar objects together and provide methods to operate on them.

• Collections are used to store and manipulate groups of objects

• They provide methods to add, remove, and access elements in the collection

• Examples include ArrayList, LinkedList, HashSet, and TreeMap

Promises are a feature in JavaScript that allow asynchronous operations to be handled in a more organized and readable way.

• Promises are objects that represent the eventual completion or failure of an asynchronous operation.

• They are used to handle asynchronous code and avoid callback hell.

• Promises have three states: pending, fulfilled, or rejected.

• They can be chained together using methods like .then() and .catch().

• Promises can be created using the Promise constructor or by us...read more

Event loop is a mechanism that allows a program to efficiently handle and respond to multiple events or tasks concurrently.

• Event loop is commonly used in asynchronous programming.

• It manages the execution of tasks or events in a non-blocking manner.

• Event loop continuously checks for events or tasks and executes them when they are ready.

• It helps prevent blocking and allows for efficient utilization of system resources.

• Examples of event loop implementations include Node.js event...read more

Select query to retrieve employee details from a database

• Use SELECT statement

• Specify the columns to retrieve

• Specify the table name

• Optional: Use WHERE clause for filtering

A program to reverse a given string.

• Use a loop to iterate through the characters of the string.

• Create a new string and append each character from the original string in reverse order.

• Return the reversed string.