Nidhi Tiwari

Hello, I share real scenarios I deal with as a backend engineer. Mostly around: • Java • System Design • AKS / Cloud • Production edge cases Lately I post question-based scenarios, the kind interviewers ask and the kind that actually break in production. If you enjoy solving these, consider following. New questions every day.

@javarevisited Because id is usually an integer not a string. So comparing it with abc makes no sense and can cause type conversion issues or errors depending on the database.

Interviewer: What’s wrong here? SELECT * FROM users WHERE id = 'abc';

AI is changing things so fast that sometimes it genuinely feels unreal. There was a time when making notes was an actual task. Watching a 2-hour YouTube tutorial meant sitting with a notebook for 4 hours. Pause the video. Write everything down. Rewind because you missed a point. Take screenshots. Highlight important timestamps. Now I just paste the YouTube link into NotebookLM and within a minute it gives me proper notes, summaries, key points, FAQs, even a podcast-style discussion from the same content. What’s crazy is not just the tool itself. It’s how normal all this is starting to feel.Things that genuinely took hours of effort now happen in minutes. Feels like AI is quietly changing the way humans learn, work, study, research… everything. #AI #notebookllm #notes

@SumitM_X All 10 APIs are tied to one big DTO, so if you change even one field, you risk breaking everything. It’s tightly coupled and hard to maintain.

You see this DTO: class OrderDTO { public String userName; public String userEmail; public String userAddress; public String productName; public double price; public String paymentStatus; } This DTO is returned by 10 different APIs. What long-term design problem do you see?

it’s not immediately garbage collected. When you do emp = null, you’re just removing your reference to the object. It’s like you’ve stopped pointing to it but the object is still sitting in memory. The garbage collector will clean it up later whenever it runs and sees that nothing is using that object anymore. You don’t control exactly when that happens.

Employee emp = new Employee(); emp = null; Is the emp object immediately garbage collected?

@SumitM_X First I’d not assume it’s harmless. I’d check memory usage and GC logs to confirm there’s actually a leak then diff recent changes and profile the app to see what’s retaining objects.

You replaced: if (x == null) with Objects.isNull(x) No logic change. Production memory usage started increasing gradually. What's your next step ?

@GamewithDave Super Mario

For anyone who used a computer between 1990 & 2005… what’s the one game you still think about?

@javarevisited it has no WHERE clause, so it updates all rows in the table not just a specific user. In this case, every user would be granted admin privileges at once, which is a serious security breach and can completely break the system’s access control.

Interviewer: Why is this risky? UPDATE users SET is_admin = true;

10 rows from the Customers table, starting after the first 10 rows. So you get rows 11 to 20 based on whatever ordering the database uses. If there is no ORDER BY clause, the rows returned are not guaranteed to be consistent. the “first 10” depends on how the database physically stores or retrieves data. PS: I post similar content. Please check out my page and follow if it interests you.

What will this query return - SELECT CustomerID, Name, Email FROM Customers LIMIT 10 OFFSET 10;

@ASpittel Old idea, new buzzwords. still runs at 3am.

cron jobs are going through the most epic rebrand

@ThePrimeagen Expectations loading faster than the model

I cannot wait for gpt 5.5 here in ~30 minutes

@dpratyush02 Owning the platform = owning attention + access. You don’t charge users. You charge anyone who wants to reach them.

Interviewer: If WhatsApp is free, how does it store billions of messages, photos, and videos while keeping everything secure without charging users?

@vandanasoc28779 I post bout java, system design and AKS. Please check out my Page and follow if it interests you.

It hasn’t even been a month since I started posting on X, and today I crossed 500 followers. Grateful for the support so far 🤝 If you're into tech, let’s connect.

@bluewmist I remove choice. Fixed time, fixed routine. No decision, no excuses. Parkinson’s Law: work expands to fill the time you give it.

People who exercise even when they don't feel like it, what's your trick?

@AishwaryaDevv Wait till they hear about REST, they’ll start looking for a couch

My intern is trying to find "Jason's desk" because the Senior Dev said we need to "send the data to JSON" 😭😭

@EOEboh Orchestrator sounds cool but someone still needs to know why things work.

You're no longer a coder, you're now an orchestrator

@vivoplt Cool. Now try modifying it without AI.

claude code is fucking insane i know literally NOTHING about coding. ZERO. and i just built a fully functioning web app in minutes. http://localhost:3000/ check it out

@bidhaan_daju VS code

which editor do you actually code in? > VS Code > Vim > JetBrains > Notepad 💀

@javarevisited ecause Kafka is built for streams, not state. Kafka-> append-only log (event history) Database -> current state (query, update, index) Kafka can store data, but, No efficient querying No relational constraints No flexible updates

Interviewer: If Kafka persists messages, why do we still need databases?

Raw types in Java skip type safety-> Bugs show up at runtime. #Java #Programming #Coding #JavaTips #BestPractices #Developers #SoftwareEngineering

@Zoomie175 Hey, so glad it helped you.

@NidhiDevNotes The questions you post on multi-threading and Arraylists helped me in tcs xplore java exam yesterday 🙌🏻

Arrays in Java: the most basic DS, but still powerful public int sum(int[] nums) { int total = 0; for (int num : nums) { total += num; } return total; } Why beginners should care: Arrays teach you the core habit. Traverse data, process each element Everything builds on this: • Prefix sums • Sliding window • Dynamic programming Real insight: If you can’t solve problems with arrays, you won’t solve them with complex DS either. Start simple. Go deep. #Java #DataStructures #DSA #Beginners #Coding