Birbal AI Java Engineer Interview Questions and Answers

Q1. No one showed up to interview
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Q2. Even they don’t responded to my mails
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1. Find longest repeating character from back.
2. Find all non-duplicates in an array and return in sorted manner.

Q1. Suppose we have more 2 interfaces with the same default method. What will happen when we try to implment both the interfaces in the same class.?
Ans. 
The class will have to provide its own implementation of the conflicting default method.
• When implementing multiple interfaces with the same default method, a class must provide its own implementation of the conflicting method.

• The class cannot inherit the default implementation from both interfaces.

• The class can choose to implement one of the default methods and provide its own implementation for the other.

• Alternatively...read more
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Q2. Terminal vs Intermediate Operations in streams
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Terminal operations in streams produce a result or a side effect, while intermediate operations transform or filter the data.
• Terminal operations are the final operations in a stream pipeline, such as forEach, collect, or reduce.

• Intermediate operations are operations that can be chained together, such as filter, map, or sorted.

• Terminal operations trigger the processing of the stream and produce a result or a side effect...read more
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Q3. Try vs try-with-resources
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try vs try-with-resources
• The 'try' statement is used to define a block of code to be tested for exceptions.

• The 'try-with-resources' statement is used to automatically close resources that implement the AutoCloseable interface.

• Try-with-resources is more concise and less error-prone compared to try-catch-finally.

• Try-with-resources can handle multiple resources in a single statement.
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Q4. Iterator vs ListIterator
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Iterator is a universal interface for iterating over a collection, while ListIterator is a specialized interface for iterating over lists.
• Iterator can only move forward, while ListIterator can move in both directions.

• ListIterator has additional methods like previous(), hasPrevious(), and add().

• ListIterator is only available for List implementations, while Iterator can be used with any collection.
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Q5. What are projections in Spring Data JPA?
Ans. 
Projections in Spring Data JPA allow customizing the shape of the data returned from a query.
• Projections are used to retrieve specific fields or a subset of fields from an entity.

• They help in reducing the amount of data transferred over the network.

• Projections can be defined using interfaces or classes.

• They can be used with both JPQL and native SQL queries.

• Projections can be used to fetch related entities as well.
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Q6. What are the two types of compiler in angular?
Ans. 
The two types of compiler in Angular are JIT (Just-in-Time) compiler and AOT (Ahead-of-Time) compiler.
• JIT compiler compiles the code at runtime in the browser.

• AOT compiler compiles the code before the application is deployed to the browser.

• JIT compilation is slower but allows for faster development and debugging.

• AOT compilation is faster but requires additional build step before deployment.
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Q7. What are the different types of data binding in Angular?
Ans. 
Data binding in Angular allows automatic synchronization of data between the model and the view.
• Interpolation: {{ }} - binds data from the component to the view

• Property binding: [] - binds data from the component to an element property

• Event binding: () - binds an event from the view to a method in the component

• Two-way binding: [()] - combines property and event binding to achieve two-way data flow
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Q8. Promises vs Observables
Ans. 
Promises are used for asynchronous programming in JavaScript, while Observables are used for reactive programming.
• Promises represent a single value that may be available now or in the future.

• Observables represent a stream of values that can be emitted over time.

• Promises are eager, meaning they start executing as soon as they are created.

• Observables are lazy, meaning they only start executing when subscribed to.

• Promises...read more
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Q9. Constructor vs ngOnInit
Ans. 
Constructor is a special method used to initialize an object, while ngOnInit is a lifecycle hook in Angular.
• Constructor is used to create and initialize an object of a class.

• ngOnInit is a lifecycle hook in Angular that is called after the component is initialized.

• Constructor is defined using the constructor keyword, while ngOnInit is a method defined in the component class.

• Constructor is called only once during the cre...read more
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Q10. When to use Inline Template vs External Template in Angular?
Ans. 
Inline templates are used for small, simple templates, while external templates are used for larger, complex templates.
• Inline templates are defined within the component's TypeScript file using the template property.

• External templates are defined in separate HTML files and linked to the component using the templateUrl property.

• Inline templates are useful for small components or when the template is simple and doesn't re...read more
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Q11. Which module is used for http calls in Angular?
Ans. 
HttpClient module is used for http calls in Angular.
• HttpClient module is part of the @angular/common/http package.

• It provides a simplified API for making HTTP requests.

• It supports various HTTP methods like GET, POST, PUT, DELETE, etc.

• It also supports features like request/response headers, query parameters, error handling, etc.

• Example: import { HttpClient } from '@angular/common/http';
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Good coding questions related array and string

Q1. What is Custom exception?
Ans. 
Custom exception is a user-defined exception that extends the functionality of the built-in exceptions in Java.
• Custom exceptions are created by extending the Exception class or one of its subclasses.

• They allow developers to define their own exception types for specific scenarios.

• Custom exceptions can include additional methods and fields to provide more information about the exception.

• Example: public class CustomExcept...read more
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Q2. What is roles and responsibilities in your project?
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Q3. Find out duplicate element in array?
Ans. 
Use a HashSet to find duplicate elements in an array of strings.
• Create a HashSet to store unique elements.

• Iterate through the array and check if the element is already in the HashSet.

• If it is, then it is a duplicate element.

• Example: String[] array = {"apple", "banana", "apple", "orange"};
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Q1. What are the advantages of spring boot
Ans. 
Spring Boot provides a simplified way to create stand-alone, production-grade Spring-based Applications.
• Rapid application development

• Embedded server for easy deployment

• Auto-configuration for setting up Spring projects quickly

• Microservices support

• Actuator for monitoring and managing applications
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Q2. Java oops concept and sql questions
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Q1. Questions on the current project
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Q2. Microservices architecture in spring microservices
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Microservices architecture in Spring is a way of designing software applications as a collection of loosely coupled services.
• Microservices architecture breaks down a large application into smaller, independent services that can be developed, deployed, and scaled independently.

• Spring Boot and Spring Cloud are commonly used frameworks for building microservices in Java.

• Each microservice typically has its own database and...read more
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Q1. In java How hasmap works internally
Ans. 
HashMap is a data structure that stores key-value pairs and uses hashing to retrieve values.
• HashMap uses an array of buckets to store key-value pairs

• The hash code of the key is used to determine the index of the bucket

• If multiple keys have the same hash code, they are stored in a linked list within the bucket

• HashMap allows null keys and values

• HashMap is not thread-safe and requires synchronization for concurrent access
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Q2. Write program in java to print even no by one thread and odd no by another thread
Ans. 
Program to print even and odd numbers using two threads in Java
• Create two threads, one for even numbers and one for odd numbers

• Use a loop to generate numbers and check if they are even or odd

• Print the numbers using the respective threads

• Use synchronization to ensure alternate printing of even and odd numbers
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