PureSoftware Senior Leader Engineer Interview Questions and Answers

HashMap is not thread-safe while ConcurrentHashMap is thread-safe.

• HashMap is not thread-safe and can lead to ConcurrentModificationException if modified during iteration.

• ConcurrentHashMap allows concurrent read and write operations without the need for external synchronization.

• ConcurrentHashMap achieves thread-safety by dividing the map into segments, allowing multiple threads to operate on different segments concurren

To find the third highest salary in a SQL table, use the 'SELECT DISTINCT' statement with 'ORDER BY' and 'LIMIT'.

• Use 'SELECT DISTINCT' to avoid duplicates

• Order the salaries in descending order using 'ORDER BY'

• Use 'LIMIT 2,1' to skip the first two highest salaries and retrieve the third highest salary