VVDN Technologies Java Developer Interview Questions and Answers

3 coding questions are given.Time 1 hr

Q1. Java collections.prepare all collections concepts
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Q1. What is multithreading
Ans. 
Multithreading is the ability of a CPU to execute multiple threads concurrently, allowing for better performance and responsiveness.
• Multithreading allows multiple tasks to be executed simultaneously on a single CPU.

• Each thread has its own stack and runs independently, but shares the same memory space.

• Example: A web server handling multiple requests concurrently using multithreading.

• Example: A video player playing video...read more
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Q2. What is interface and abstraction
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Interface is a blueprint of a class that defines methods without implementation. Abstraction is a concept where only essential details are shown and irrelevant details are hidden.
• Interface in Java is a reference type, similar to a class, that can contain only constants, method signatures, default methods, static methods, and nested types.

• Abstraction is achieved in Java using abstract classes and interfaces. Abstract cl...read more
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It was an intermediate level aptitude questions

This was also intermediate

Q1. That was a friendly round
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Q1. Diff between abstract class and interface
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructor, fields, and methods, while interface cannot have any of these.

• A class can extend only one abstract class, but can implement multiple interfaces.

• Abstract classes are used to define a common behavior among subclasses, while interfaces are used to define a contract for classes...read more
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Q2. Explain about handler methods
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Handler methods in Java are methods that are responsible for handling incoming requests and generating responses.
• Handler methods are typically defined in classes annotated with @Controller or @RestController.

• These methods are mapped to specific URLs using @RequestMapping or other mapping annotations.

• Handler methods can have parameters such as HttpServletRequest, HttpServletResponse, or model attributes.

• The return value...read more
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