Hvirtuals Django Developer Interview Questions and Answers for Experienced

finally is used to execute a block of code after try-catch block, while static block is executed when class is loaded.

• finally block is used to perform cleanup operations like closing database connections, file streams etc.

• static block is used to initialize static variables or perform any other static initialization.

• finally block is always executed whether an exception is thrown or not, while static block is executed on...read more

The @Autowired annotation in Spring is used to automatically wire dependencies into a bean.

• It eliminates the need for manual wiring of dependencies

• It can be used to inject dependencies into constructors, fields, and methods

• It can be used with other annotations like @Qualifier and @Value

• It can be used with both XML and Java-based configurations

To make a class immutable in Java, we need to follow certain guidelines.

• Make the class final

• Make all fields private and final

• Do not provide setter methods

• If the field is mutable, return a clone of it instead of the original object

• Ensure that any mutable objects passed to the constructor are not modified outside the class

Collections are data structures that store and manipulate groups of objects.

• Collections provide a way to manage and manipulate groups of objects

• Java provides several built-in collection classes such as ArrayList, LinkedList, HashSet, etc.

• Collections can be used to perform operations like searching, sorting, filtering, etc.

• Collections can store objects of any type, including primitive types and user-defined classes

ArrayList and Vector are similar but Vector is synchronized while HashMap and HashTable are both key-value pair data structures but HashTable is synchronized.

• ArrayList and Vector both implement List interface but Vector is thread-safe while ArrayList is not.

• Vector is slower than ArrayList due to synchronization.

• HashMap and HashTable both store key-value pairs but HashTable is thread-safe while HashMap is not.

• HashMap al...read more

Rest Api is a web service that uses HTTP methods to access and manipulate data.

• Rest stands for Representational State Transfer

• It is an architectural style for building web services

• Uses HTTP methods like GET, POST, PUT, DELETE

• Data is transferred in JSON or XML format

• Examples: Twitter API, Facebook Graph API

Program to add numbers in harmonic series (1+1/2+1/3+...+1/n)

• Create a variable to store the sum

• Use a loop to iterate through the series up to n

• Add each term to the sum

• Print the sum

Batchable interface has three methods: start(), execute(), and finish().

• start() method is used to initialize the batch job and return the query locator.

• execute() method is used to process the records returned by the query locator.

• finish() method is used to perform any final operations after the batch job completes.

Access modifiers in Apex control the visibility and accessibility of classes, methods, variables, and interfaces.

• There are three access modifiers in Apex: private, public, and global.

• Private access modifier restricts access to only within the defining class.

• Public access modifier allows access from any other class or trigger.

• Global access modifier allows access from any Apex code in any Salesforce organization.

• Access m...read more

There are multiple ways to write asynchronous code in Salesforce.

• Using @future annotation

• Using Queueable interface

• Using Batch Apex

• Using Platform Events

• Using Asynchronous Apex REST Callouts

Order of Execution in Salesforce determines the sequence of events that occur when a record is saved.

• Validation rules are executed first

• Before triggers are executed next

• Custom validation rules are executed after before triggers

• After triggers are executed next

• Assignment rules are executed after after triggers

• Workflows are executed after assignment rules

• Escalation rules are executed after workflows

• Finally, the record is

Annotations are used in Salesforce to add metadata to classes, methods, and variables.

• Annotations are used to provide additional information to the compiler or runtime engine.

• They can be used to control the behavior of code, such as enforcing security or limiting access.

• Examples of annotations include @AuraEnabled, @TestSetup, and @Deprecated.

• Annotations can also be used to provide documentation for code, such as @desc...read more

Coding best practices ensure efficient, maintainable, and scalable code.

• Use meaningful variable and function names

• Follow a consistent coding style

• Write modular and reusable code

• Use version control

• Write unit tests

• Optimize code for performance

• Document code and add comments