Virinchi Technologies Java Developer Interview Questions and Answers

Q1. They asked some core Java Concepts,String,Java 8,SpringBoot Architecture,Stream API code
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Q1. Java 8 feature & java 9
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Q2. Profiler concept internal work
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Separate 0 and 1 and then store in the sme array

Q1. Java 8 features
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Q2. Junit code writing
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Q1. Reason for job change
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Seeking new challenges and growth opportunities in a dynamic environment.
• Desire for professional growth

• Seeking new challenges

• Interested in a more dynamic work environment
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Q2. Past experience
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Q1. Difference between ArrayList and LinkedList?
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ArrayList is implemented as a resizable array, while LinkedList is implemented as a doubly linked list.
• ArrayList provides fast random access, LinkedList provides fast insertion and deletion.

• ArrayList uses more memory as it needs to allocate a fixed size array, LinkedList uses more memory for storing references to the next and previous elements.

• Example: ArrayList is better for scenarios where random access is required, ...read more
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Q2. Difference between HashMap and HashTable?
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HashMap is non-synchronized and allows null values, while HashTable is synchronized and does not allow null values.
• HashMap is non-synchronized, meaning it is not thread-safe, while HashTable is synchronized and thread-safe.

• HashMap allows null values for both keys and values, while HashTable does not allow null keys or values.

• HashMap is faster than HashTable as it is non-synchronized, but HashTable is preferred in multi...read more
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Q1. What is the contract between hashCode and equals method?
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The contract between hashCode and equals method is that if two objects are equal according to the equals method, then their hash codes must also be equal.
• hashCode and equals method must be consistent - if two objects are equal according to equals method, their hash codes must be equal

• If two objects have the same hash code, they may or may not be equal according to equals method

• Overriding equals method in a class requir...read more
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Q2. Features introduced in Java 8
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Java 8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods in interfaces.
• Lambda expressions allow you to pass functions as arguments.

• Functional interfaces have a single abstract method and can be used with lambda expressions.

• Streams provide a way to work with sequences of elements.

• Default methods allow interfaces to have method implementations.
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Q3. What are the ways to start a thread
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Ways to start a thread in Java
• Extending the Thread class and overriding the run() method

• Implementing the Runnable interface and passing it to a Thread object

• Using a thread pool from the Executors class
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Q4. What will happen if you start a thread which is already running
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The thread will continue running as it is already active
• The thread will not be started again if it is already running

• Attempting to start a thread that is already running will not have any effect

• The thread will continue its execution without any interruption
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Q5. Explain about the join and sleep method
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Join method is used to wait for a thread to finish its execution, while sleep method is used to pause the execution of a thread for a specified amount of time.
• Join method is used to wait for a thread to finish its execution before moving on to the next task.

• Sleep method is used to pause the execution of a thread for a specified amount of time, allowing other threads to run.

• Example: thread1.join() will wait for thread1 ...read more
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Q1. Micro service disadvantage
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Microservices can introduce complexity, communication overhead, and potential performance issues.
• Increased complexity due to managing multiple services

• Communication overhead between services

• Potential performance issues due to network latency

• Difficulty in maintaining consistency across services
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Q2. @functionalinterface can we extend or not, map & flatmap
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No, @FunctionalInterface cannot be extended. Map and flatMap are default methods in the interface and cannot be overridden.
• No, @FunctionalInterface cannot be extended as it is a single abstract method interface.

• Map and flatMap are default methods in the interface and cannot be overridden.

• Example: public interface MyInterface { void myMethod(); default void myDefaultMethod() { // implementation } }
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