10+ Bol7 Technologies Interview Questions and Answers

A bean in Spring is a Java object managed by the Spring IoC container. Spring bean life cycle includes instantiation, initialization, and destruction.

• A Spring bean is a Java object that is instantiated, assembled, and managed by the Spring IoC container.

• The life cycle of a Spring bean includes instantiation, initialization, in-use, and destruction phases.

• Spring provides various ways to define beans, such as XML configuration, Java configuration, and annotation-based configura...read more

Different types of object relations in Hibernate include one-to-one, one-to-many, many-to-one, and many-to-many.

• One-to-one: Each record in one table is related to only one record in another table.

• One-to-many: Each record in one table can be related to multiple records in another table.

• Many-to-one: Multiple records in one table can be related to only one record in another table.

• Many-to-many: Multiple records in one table can be related to multiple records in another table.

Asynchronous operations allow tasks to be executed independently of the main program flow, improving performance and responsiveness.

• Asynchronous operations are tasks that can run independently of the main program flow, allowing other tasks to continue without waiting for them to finish.

• In Java, asynchronous operations can be handled using features like CompletableFuture, ExecutorService, and callbacks.

• Example: Using CompletableFuture to perform a time-consuming task in a sepa...read more

I am familiar with Singleton, Factory, Observer, and Strategy design patterns.

• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Factory pattern creates objects without specifying the exact class of object that will be created.

• Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

• Strategy pattern defines a family of algo...read more

Passing an object in an API request body involves serializing the object into JSON or XML format.

• Serialize the object into JSON or XML format before sending it in the request body

• Use libraries like Jackson or Gson in Java to convert the object to JSON

• Set the content type of the request to application/json or application/xml

There are two types of cloning in JavaScript: Shallow cloning and Deep cloning.

• Shallow cloning creates a new object and copies the references of the original object's properties.

• Deep cloning creates a new object and recursively copies all nested objects and their properties.

• Shallow cloning can be achieved using Object.assign() or the spread operator (...).

• Deep cloning can be achieved using libraries like Lodash or by implementing a custom recursive function.

Lazy initialization delays the creation of an object until it is actually needed, while eager initialization creates the object immediately.

• Lazy initialization can improve performance by only creating objects when necessary.

• Eager initialization can lead to higher memory usage as objects are created upfront.

• Lazy initialization is commonly used in singleton design pattern to delay the creation of the instance until it is requested.

• Eager initialization is suitable for objects th...read more

promise.all waits for all promises to be resolved or any to be rejected, while promise.allSettled waits for all promises to be settled (either resolved or rejected)

• promise.all waits for all promises to be resolved or any to be rejected

• promise.allSettled waits for all promises to be settled (either resolved or rejected)

• promise.all will reject immediately if any promise is rejected, while promise.allSettled always resolves with an array of results

ORM framework stands for Object-Relational Mapping framework, which is used to map objects in code to tables in a database.

• ORM frameworks help developers to interact with databases using objects instead of SQL queries.

• They provide a way to perform CRUD operations on database tables using object-oriented programming.

• Popular ORM frameworks include Hibernate, JPA (Java Persistence API), and Entity Framework.

SOLID principles are a set of five design principles in object-oriented programming to make software more maintainable, flexible, and understandable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable with objects of its subclasses without affecting the functionalit...read more