Optimum Infosystem Senior Developer Lead Interview Questions and Answers for Experienced

Q1. What are the traversal conditions for a Doubly Linked List? And write a program to traverse.This was the first question and I had no answer and ended up the interview immediately by asking any questions fo...read more
Ans. 
Traversal conditions for a Doubly Linked List involve moving forward and backward through each node.
• Start at the head node and move to the next node by following the 'next' pointer.

• To traverse backward, start at the tail node and move to the previous node by following the 'prev' pointer.

• Continue this process until reaching the end of the list.
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Q1. What is the contract between hashCode and equals method?
Ans. 
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
Ans. 
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
Ans. 
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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Hackerrank coding round.

Q1. Questions and coding testing your OOPS knowledge
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Q1. Every tech stack, SQL, OOPS, JAVA
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Q1. Why functional interface when we have interface
Ans. 
Functional interfaces provide a single abstract method for functional programming in Java.
• Functional interfaces allow for lambda expressions and method references to be used as instances of the interface.

• Interfaces with multiple abstract methods cannot be used for lambda expressions.

• Example: java.util.function.Function is a functional interface with a single abstract method apply().
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Q2. Java 8 explain all features in short
Ans. 
Java 8 introduced new features like lambda expressions, streams, functional interfaces, and default methods.
• Lambda expressions: Allows writing concise code by enabling functional programming.

• Streams: Provides a way to work with sequences of elements efficiently.

• Functional interfaces: Interfaces with a single abstract method, used for lambda expressions.

• Default methods: Allows adding new methods to interfaces without br
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Q3. If one functional interface can extend another interface
Ans. 
Yes, one functional interface can extend another interface in Java.
• Functional interfaces can extend other functional interfaces in Java.

• The child interface can have only one abstract method, but can inherit default methods from the parent interface.

• Example: interface Parent { void method1(); } interface Child extends Parent { void method2(); }
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One coding question with 40-45 mcq

Q1. 2 coding questions from array
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Q2. In given array find the sum a*a+b*b=c*c
Ans. 
Use a nested loop to iterate through the array and check for the sum of squares of two elements equal to the square of a third element.
• Iterate through the array using a nested loop to compare all possible combinations of elements.

• Calculate the sum of squares of two elements and check if it equals the square of a third element.

• Return the elements if a match is found, otherwise continue iterating.
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Q1. Core java questions, springboot, one string coding question
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Q1. Exception handling
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Q1. What is java and its features ?
Ans. 
Java is a high-level programming language known for its platform independence and object-oriented features.
• Java is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM)

• It is object-oriented, allowing for the creation of reusable code and modular programs

• Java is known for its robust standard library, providing a wide range of pre-built functionality

• It supports multithreading, allowing ...read more
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Q2. What is java 8 and features
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Java 8 is a major release of the Java programming language with new features like lambda expressions, streams, and default methods.
• Lambda expressions allow you to treat functionality as a method argument.

• Streams provide a new abstraction to work with sequences of elements.

• Default methods allow interfaces to have method implementations.

• Date and Time API provides a new way to work with dates and times.

• Optional class help
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Q1. Project related questions
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