Tech Mahindra Senior Java Developer Interview Questions and Answers

Q1. What is final and finally
Ans. 
final is a keyword in Java used to declare constants, while finally is a block used in exception handling to ensure code is executed regardless of an exception.
• final keyword is used to declare constants in Java

• final variables cannot be reassigned once initialized

• finally block is used in exception handling to ensure code is executed regardless of an exception

• finally block is often used to release resources like closing ...read more
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Q2. Brief description about the last project
Ans. 
Developed a web application for a financial institution to manage customer accounts and transactions.
• Used Java Spring framework for backend development

• Implemented RESTful APIs for communication between frontend and backend

• Utilized Hibernate for database interaction

• Integrated third-party payment gateway for transactions
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Q1. What is flatMap in java 8?
Ans. 
flatMap in Java 8 is a method used to transform each element of a stream into another stream and then concatenate all the streams into a single stream.
• flatMap is used to flatten nested collections in streams.

• It is commonly used with streams of collections or arrays.

• Example: List<List<Integer>> list = Arrays.asList(Arrays.asList(1, 2), Arrays.asList(3, 4)); list.stream().flatMap(Collection::stream).forEach(Syst...read more
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Medium level Strings and Array questions

Q1. Find LCA of a node in BST
Ans. 
LCA of a node in BST is the lowest common ancestor of two nodes in a binary search tree.
• Traverse the BST from the root node to find the LCA of the given nodes.

• Compare the values of the nodes with the current node to determine the LCA.

• If one node is on the left subtree and the other is on the right subtree, the current node is the LCA.
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Q2. Optimise the above solution
Ans. 
Optimize the solution by using efficient data structures and algorithms.
• Use HashMap instead of ArrayList for faster lookup

• Implement caching to store previously calculated results

• Consider using multithreading for parallel processing
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Q1. In java How hasmap works internally
Ans. 
HashMap is a data structure that stores key-value pairs and uses hashing to retrieve values.
• HashMap uses an array of buckets to store key-value pairs

• The hash code of the key is used to determine the index of the bucket

• If multiple keys have the same hash code, they are stored in a linked list within the bucket

• HashMap allows null keys and values

• HashMap is not thread-safe and requires synchronization for concurrent access
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Q2. Write program in java to print even no by one thread and odd no by another thread
Ans. 
Program to print even and odd numbers using two threads in Java
• Create two threads, one for even numbers and one for odd numbers

• Use a loop to generate numbers and check if they are even or odd

• Print the numbers using the respective threads

• Use synchronization to ensure alternate printing of even and odd numbers
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