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

Q1. Regular core java, OOPS, Spring Boot questions. It was like a rapid-fire round.
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Q1. Coding question - find repeat elements in an array
Ans. 
Find repeat elements in an array of strings
• Iterate through the array and store each element in a HashMap with its count

• Check if the count of any element is greater than 1, then it is a repeat element

• Return the repeat elements found in the array
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Q2. Project related questions
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Q3. Build a basic CRUD REST API endpoint
Ans. 
Build a basic CRUD REST API endpoint
• Create a REST API endpoint for each CRUD operation (Create, Read, Update, Delete)

• Use HTTP methods like POST, GET, PUT, DELETE to perform CRUD operations

• Implement data validation and error handling for each operation

• Utilize a framework like Spring Boot or Express.js to simplify API development
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Q1. Behavioral questions
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Q2. Technical questions about SpringBoot and microservices
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Q3. SQL question - third highest salary
Ans. 
To find the third highest salary in a SQL table, you can use the 'SELECT TOP 1' statement with 'ORDER BY salary DESC OFFSET 2 ROWS FETCH NEXT 1 ROWS ONLY'.
• Use the 'SELECT TOP 1' statement to retrieve only one record

• Order the records by salary in descending order using 'ORDER BY salary DESC'

• Skip the first two highest salaries using 'OFFSET 2 ROWS'

• Fetch the next record after skipping the first two using 'FETCH NEXT 1 ROW
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Q1. What is hashmap
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HashMap is a data structure in Java that stores key-value pairs and allows fast retrieval of values based on keys.
• HashMap implements the Map interface in Java

• It allows null keys and values

• Keys in a HashMap must be unique

• Example: HashMap<String, Integer> map = new HashMap<>()
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Q2. Internal Working of hashmap
Ans. 
HashMap is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values.
• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where it will be stored.

• If multiple keys hash to the same index, a linked list is used to handle collisions.

• HashMap uses the hashCode() method of keys to calc...read more
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Q3. Compare Throw vs Throws
Ans. 
Throw is used to explicitly throw an exception in a method, while Throws is used to declare the exceptions that a method may throw.
• Throw is used within a method to throw an exception explicitly.

• Throws is used in the method signature to declare the exceptions that the method may throw.

• Throw is followed by an instance of Throwable class, while Throws is followed by the exception class names separated by commas.

• Example: t...read more
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Q4. Array vs Arraylist
Ans. 
Arrays are fixed in size, while ArrayLists can dynamically resize. ArrayLists provide more flexibility and functionality.
• Arrays have a fixed size, while ArrayLists can dynamically resize.

• ArrayLists can easily add, remove, or modify elements, while arrays require manual shifting of elements.

• Arrays use [] syntax for declaration and initialization, while ArrayLists use the ArrayList class from the Java Collections framewo
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Q5. Arraylist vs LinkedList/Vector
Ans. 
ArrayList is resizable array implementation, LinkedList is doubly linked list implementation, Vector is synchronized version of ArrayList.
• ArrayList is faster for accessing elements, LinkedList is faster for adding/removing elements in middle.

• ArrayList uses less memory than LinkedList due to contiguous memory allocation.

• Vector is thread-safe but slower than ArrayList due to synchronization overhead.
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Q6. Write a code for Iterate hashmap using iterator
Ans. 
Iterate through a hashmap using an iterator in Java
• Create an iterator using the entrySet() method of the hashmap

• Use a while loop to iterate through the hashmap entries

• Access the key and value of each entry using the getKey() and getValue() methods
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Q1. Spring Boot basics
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Q2. SQL basics and query
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Basic coding on java 8

Q1. About domain and coding functionality also asked about lwd and how soon can join
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Q2. Coding on java8
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