Cognizant Java Developer Interview Questions, Process, and Tips for Experienced

Q1. Prime number program
Ans. 
A program to check if a given number is prime or not.
• Create a function to check if a number is prime by iterating from 2 to the square root of the number.

• If the number is divisible by any number other than 1 and itself, it is not prime.

• Handle edge cases like 0, 1, and negative numbers separately.
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Q2. 3rd highest salary employee
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To find the 3rd highest salary employee, we can use a SQL query with the 'LIMIT' and 'OFFSET' keywords.
• Use a SQL query to select distinct salaries in descending order

• Use 'LIMIT 1 OFFSET 2' to get the 3rd highest salary

• Join this result with the employee table to get the employee details
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1 round in fresher Java coding test

Second Java aptitude test

Q1. What JDK,JRE,JVM
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Q2. What is inheritance
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Q1. What is Static Method?
Ans. 
Static method is a method that belongs to the class itself, not to any specific instance of the class.
• Static methods can be called without creating an instance of the class.

• They are commonly used for utility methods that do not require access to instance variables.

• Static methods are declared using the 'static' keyword.

• Example: Math.max() is a static method in the Math class that returns the maximum of two numbers.
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Q2. LAMDA EXPRESSION?
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Q1. How to make class immutable?
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To make a class immutable in Java, you can follow certain guidelines to ensure that its state cannot be changed once it is created.
• Make the class final so that it cannot be extended.

• Make all fields private and final to prevent modification.

• Do not provide setter methods for the fields.

• If the fields are mutable objects, return copies of them instead of the original objects in getter methods.
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Q2. What is idempotency? Solid ? Design patterns used in projects
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Idempotency is the property of an operation where multiple identical requests have the same effect as a single request.
• Idempotency ensures that even if the same request is made multiple times, the result will be the same.

• In RESTful APIs, using HTTP methods like GET and PUT can help achieve idempotency.

• Design patterns like Command Pattern and State Pattern can be used to ensure idempotency in projects.
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