Multithreading, synchronization, and thread lifecycle.

His finger hovered. Duplicate key “a” → throws IllegalStateException . Right? But the test offered “creates a map with last value” as a distractor. He knew better. Or did he?

: Once you submit an answer or skip a question, it is gone forever.

Start your 4-week plan today. Practice the tricky edge cases. And remember: the difference between a good developer and a great one is understanding not just what works, but when and why it fails.

Example of a new-style question: Given a stream of transactions, group them by currency and then sum the amounts, handling null values gracefully. Which combination of Collectors methods would you use?

Two interfaces with same default method m() → class must override.

Arjun clicked “default” instantly. Too easy.

The updated test assumes you know filter() and map() . Now they focus on: