Celestial Systems Backend Developer Interview Questions and Answers

It's about implementing rest apis

Q1. Java 8 interview
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Q2. Rest api development
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Normal java coding question

Q1. What are spring ioc
Ans. 
Spring IoC (Inversion of Control) is a design pattern where the control of object creation and lifecycle is shifted to a container or framework.
• In Spring IoC, objects are created and managed by the Spring container.

• It helps in achieving loose coupling between classes.

• Dependency Injection is a key feature of Spring IoC, where dependencies of a class are injected by the container.

• Example: @Autowired annotation in Spring
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Q2. Different implementation of map interface
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The Map interface in Java provides a way to store key-value pairs and retrieve values based on keys.
• Different implementations of the Map interface include HashMap, TreeMap, LinkedHashMap, and ConcurrentHashMap.

• HashMap provides constant-time performance for basic operations but does not guarantee the order of elements.

• TreeMap maintains elements in sorted order based on keys.

• LinkedHashMap maintains the insertion order of...read more
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Q1. Could you provide an in-depth discussion about your current project?
Ans. 
Currently, I am working on a scalable microservices architecture for an e-commerce platform.
• Utilized Node.js and Express for building RESTful APIs, ensuring efficient data handling.

• Implemented Docker for containerization, allowing seamless deployment across different environments.

• Integrated MongoDB for a NoSQL database solution, optimizing data retrieval and storage.

• Employed RabbitMQ for message queuing, enhancing comm...read more
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Q2. What occurs behind the scenes when a URL is entered into a browser?
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Entering a URL triggers a series of network and server interactions to retrieve and display the requested web page.
• 1. DNS Resolution: The browser checks the URL and queries a DNS server to translate the domain name into an IP address.

• 2. TCP Connection: A TCP connection is established with the server using the IP address, typically over port 80 (HTTP) or 443 (HTTPS).

• 3. HTTP Request: The browser sends an HTTP request to ...read more
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Q1. Screening of the resume
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Q2. Regarding candidature
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Q1. Related to job profile and technical requirements
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Q1. Salary structure and the part of joining date
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Q1. Project based, oops concepts, average dsa questions,
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Q1. String palindrome
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Q2. Find all anagrams in a string
Ans. 
Find all anagrams in a string
• Create a hashmap to store the frequency of characters in the input string

• Iterate through the input string and check if the frequency of characters matches the hashmap for each substring of the same length

• Store the substrings that are anagrams in an array and return it
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Q1. Describe Life cycle in react
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React has three main phases in its lifecycle: mounting, updating, and unmounting.
• Mounting: when a component is created and inserted into the DOM

• Updating: when a component is updated due to changes in props or state

• Unmounting: when a component is removed from the DOM

• Lifecycle methods can be used to perform actions at each phase, such as componentDidMount() or componentWillUnmount()

• React also has error handling methods,
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Q2. Explain strict mode in javascript and it's use
Ans. 
Strict mode is a way to write secure and optimized JavaScript code.
• Enables catching of silent errors

• Disallows duplicate property names or parameters

• Prevents use of undeclared variables

• Makes `eval()` safer to use

• Throws errors on invalid usage of `this` keyword
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CURD operations along with implementation of a mock UI

Q1. Tell about Oops concepts
Ans. 
OOPs concepts are fundamental principles in object-oriented programming, including inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex imple...read more
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Q1. Will ask coding related
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Q1. What is Expected salary
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