Top 10 Java Interview Questions

1. What is Java and what are its key features?
Java is a high-level, class-based, object-oriented programming language designed to have as few implementation dependencies as possible. Its key features include platform independence (write once, run anywhere), object-oriented, robustness, security, multithreading, and high performance through Just-In-Time (JIT) compiler.

2. Explain the difference between JDK, JRE, and JVM.
- JDK (Java Development Kit): A full-featured software development kit required to develop Java applications, including JRE and development tools like the compiler and debugger.
- JRE (Java Runtime Environment): A set of software tools for running Java applications, including JVM and libraries but no development tools.
- JVM (Java Virtual Machine): An abstract machine that provides a runtime environment to execute Java bytecode, making Java platform-independent.

3. What is the difference between an abstract class and an interface in Java?
- Abstract Class: Can have both abstract methods (without implementation) and concrete methods (with implementation). It can have state (instance variables).
- Interface: Can only have abstract methods (Java 8 allows default and static methods). It cannot have state. An interface is implemented by classes.

4. Explain the concept of inheritance in Java.
Inheritance is a mechanism in Java where one class (subclass/child class) inherits the fields and methods of another class (superclass/parent class). It promotes code reusability and establishes a parent-child relationship between classes. Inheritance is implemented using the extends keyword.

5. What is polymorphism in Java and how is it implemented?
Polymorphism allows objects to be treated as instances of their parent class rather than their actual class. It can be implemented in two ways:
- Compile-time polymorphism: Achieved through method overloading.
- Runtime polymorphism: Achieved through method overriding.

6. How does exception handling work in Java?
Exception handling in Java is managed using try, catch, finally, and throw/throws. The try block contains code that might throw an exception, catch block handles the exception, finally block executes code regardless of whether an exception occurs, and throw/throws is used to throw exceptions.

7. What is the difference between ArrayList and LinkedList in Java?
- ArrayList: Implements the List interface using a dynamic array. It offers constant-time positional access but is slow for inserting or deleting elements from the middle.
- LinkedList: Implements the List and Deque interfaces using a doubly-linked list. It offers faster insertions and deletions but slower positional access compared to ArrayList.

8. Explain the concept of multithreading in Java.
Multithreading is a process of executing multiple threads simultaneously to maximize CPU utilization. Threads are lightweight sub-processes, and Java provides built-in support for multithreading through the java.lang.Thread class and the java.util.concurrent package.

9. What is the purpose of the final keyword in Java?
The final keyword is used to define constants, prevent method overriding, and inheritance. When applied to a variable, it makes it a constant. When applied to a method, it prevents subclasses from overriding it. When applied to a class, it prevents the class from being subclassed.

10. What is garbage collection in Java and how does it work?
Garbage collection is an automatic memory management feature in Java that deallocates memory occupied by objects that are no longer in use, preventing memory leaks. The JVM’s garbage collector identifies and removes these objects. Java developers can request garbage collection using System.gc(), but it is not guaranteed to run immediately.

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Study these 45 problems well and you have prepared for 99% of your System Design Interview:

𝐄𝐚𝐬𝐲
1. Design URL Shortener like TinyURL
2. Design Text Storage Service like Pastebin
3. Design Content Delivery Network (CDN)
4. Design Parking Garage
5. Design Vending Machine
6. Design Distributed Key-Value Store
7. Design Distributed Cache
8. Design Distributed Job Scheduler
9. Design Authentication System
10. Design Unified Payments Interface (UPI)

𝐌𝐞𝐝𝐢𝐮𝐦
11. Design Instagram
12. Design Tinder
13. Design WhatsApp
14. Design Facebook
15. Design Twitter
16. Design Reddit
17. Design Netflix
18. Design Youtube
19. Design Google Search
20. Design E-commerce Store like Amazon
21. Design Spotify
22. Design TikTok
23. Design Shopify
24. Design Airbnb
25. Design Autocomplete for Search Engines
26. Design Rate Limiter
27. Design Distributed Message Queue like Kafka
28. Design Flight Booking System
29. Design Online Code Editor
30. Design Stock Exchange System
31. Design an Analytics Platform (Metrics & Logging)
32. Design Notification Service
33. Design Payment System

𝐇𝐚𝐫𝐝
34. Design Location Based Service like Yelp
35. Design Uber
36. Design Food Delivery App like Doordash
37. Design Google Docs
38. Design Google Maps
39. Design Zoom
40. Design File Sharing System like Dropbox
41. Design Ticket Booking System like BookMyShow
42. Design Distributed Web Crawler
43. Design Code Deployment System
44. Design Distributed Cloud Storage like S3
45. Design Distributed Locking Service

Best DSA RESOURCES: https://topmate.io/coding/886874

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Facing challenges while solving coding questions ? 🤔

Here are 20 essential coding patterns you need to know:

1. ✌️ Two Pointers

2. 🏝️ Island (Matrix Traversal)

3. ⏩ Fast & Slow Pointers

4. 🚶‍♂️ Sliding Window

5. 📅 Merge Intervals

6. 🔄 Cyclic Sort

7. 🔙 In-place Reversal of a Linked List

8. 🌳 Tree Breadth First Search

9. 🌲 Tree Depth First Search

10. ⚖️ Two Heaps

11. 🌈 Subsets

12. 🔍 Modified Binary Search

13. 🏆 Top ‘K’ Elements

14. ❌⭕ Bitwise XOR

15. 🔄 Backtracking

16. 🎒 0/1 Knapsack (Dynamic Programming)

17. 🔗 Topological Sort (Graph)

18. 🧩 K-way Merge

19. 📏 Monotonic Stack

20. 🤹‍♂️ Multi-threaded

Best DSA RESOURCES: https://topmate.io/coding/886874

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Tips for solving leetcode codings interview problems

If input array is sorted then
- Binary search
- Two pointers

If asked for all permutations/subsets then
- Backtracking

If given a tree then
- DFS
- BFS

If given a graph then
- DFS
- BFS

If given a linked list then
- Two pointers

If recursion is banned then
- Stack

If must solve in-place then
- Swap corresponding values
- Store one or more different values in the same pointer

If asked for maximum/minimum subarray/subset/options then
- Dynamic programming

If asked for top/least K items then
- Heap

If asked for common strings then
- Map
- Trie

Else
- Map/Set for O(1) time & O(n) space
- Sort input for O(nlogn) time and O(1) space

You can check these resources for Coding interview Preparation

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DSA is really tough, but you don't seem to struggle?🤨

I get this question a lot.

Here are some of the hardest questions you might face in an interview.

Practice these using the 𝟯-𝟳-𝟭𝟱 𝗿𝘂𝗹𝗲:

First solve the question, then note down the answer. After three days, try to remember the question from the answer and solve it again.

Repeat the same after 7 and 15 days.

This way, you'll solve the same question 4 times in 15 days, making it easier if you encounter it again.

𝟭. 𝗔𝗿𝗿𝗮𝘆𝘀 & 𝗦𝘁𝗿𝗶𝗻𝗴𝘀
- Minimum Window Substring
- Trapping Rain Water
- Largest Rectangle in Histogram

𝟮. 𝗟𝗶𝗻𝗸𝗲𝗱 𝗟𝗶𝘀𝘁𝘀
- Merge k Sorted Lists
- Reverse Nodes in k-Group
- LFU Cache

𝟯. 𝗧𝗿𝗲𝗲𝘀
- Binary Tree Maximum Path Sum
- Serialize and Deserialize Binary Tree
- Vertical Order Traversal of a Binary Tree

𝟰. 𝗗𝘆𝗻𝗮𝗺𝗶𝗰 𝗣𝗿𝗼𝗴𝗿𝗮𝗺𝗺𝗶𝗻𝗴
- Edit Distance
- Burst Balloons
- Shortest Common Supersequence

𝟱. 𝗚𝗿𝗮𝗽𝗵𝘀
- Alien Dictionary
- Minimum Cost to Make at Least One Valid Path in a Grid
- Swim in Rising Water

𝟲. 𝗥𝗲𝗰𝘂𝗿𝘀𝗶𝗼𝗻 & 𝗕𝗮𝗰𝗸𝘁𝗿𝗮𝗰𝗸𝗶𝗻𝗴
- N-Queens II
- Sudoku Solver
- Word Search II

𝟳. 𝗦𝗼𝗿𝘁𝗶𝗻𝗴 & 𝗦𝗲𝗮𝗿𝗰𝗵𝗶𝗻𝗴
- Count of Smaller Numbers After Self
- Median of Two Sorted Arrays
- Split Array Largest Sum

𝟴. 𝗗𝗲𝘀𝗶𝗴𝗻
- Design Search Autocomplete System
- Design In-Memory File System
- Design Excel Sum Formula

𝟵. 𝗚𝗿𝗲𝗲𝗱𝘆
- Minimum Number of Arrows to Burst Balloons
- Candy
- Patching Array

𝟭𝟬. 𝗕𝗶𝘁 𝗠𝗮𝗻𝗶𝗽𝘂𝗹𝗮𝘁𝗶𝗼𝗻
- Maximum Product of Word Lengths
- Smallest Sufficient Team
- Minimum Cost to Connect Two Groups of Points

𝟭𝟭. 𝗧𝘄𝗼 𝗣𝗼𝗶𝗻𝘁𝗲𝗿𝘀
- Minimum Window Subsequence
- Minimum Operations to Make a Subsequence
- Minimum Adjacent Swaps to Reach the Kth Smallest Number

𝟭𝟮. 𝗛𝗲𝗮𝗽
- Minimum Number of Refueling Stops
- Sliding Window Median
- Minimum Number of K Consecutive Bit Flips

By following the 3-7-15 rule and practicing these tough questions regularly, you'll build strong problem-solving skills and be well-prepared for your interviews.

Keep pushing yourself, and remember, consistency is key.

Best DSA RESOURCES: https://topmate.io/coding/886874

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System design interviews will never crack until you know this hack !

If you’re a working professional targeting for senior roles at PBCs then


Here's a simple approach to crack it:

𝗔𝘁𝘁𝗶𝘁𝘂𝗱𝗲: Stay playful and collaborative.

𝗦𝗰𝗼𝗽𝗲: Ask targeted questions to narrow down the scope.

𝗖𝗼𝗺𝗽𝗼𝗻𝗲𝗻𝘁𝘀: Understand and use the main infrastructure components like LEGO pieces.


Here's a quick overview of the 10 main elements to consider during a system design interview. What you discuss will depend on your prompt.

𝟭. 𝗙𝗲𝗮𝘁𝘂𝗿𝗲𝘀 - Start with the main features of the system. For example, if asked to design Twitter, list its key features. This helps ensure you're aligned with the interviewer.

𝟮. 𝗨𝘀𝗲𝗿𝘀 - Consider the types of users, usage patterns, and growth rates. Identify peak times and regions.

𝟯. 𝗗𝗮𝘁𝗮 𝗠𝗼𝗱𝗲𝗹 - Decide between relational and NoSQL databases based on your use case. Plan your tables, indexing, and replication strategies.

𝟰. 𝗚𝗲𝗼𝗴𝗿𝗮𝗽𝗵𝘆 & 𝗟𝗮𝘁𝗲𝗻𝗰𝘆 - Reduce latency with servers in different regions. Use CDNs to serve content faster.

𝟱. 𝗦𝗲𝗿𝘃𝗲𝗿 𝗖𝗮𝗽𝗮𝗰𝗶𝘁𝘆 - Determine CPU, RAM, and storage needs. Plan for vertical and horizontal scaling.

𝟲. 𝗔𝗣𝗜𝘀 & 𝗦𝗲𝗰𝘂𝗿𝗶𝘁𝘆 - Choose between REST, GraphQL, or gRPC for your APIs. Address security concerns and implement rate limiting.

𝟳. 𝗔𝘃𝗮𝗶𝗹𝗮𝗯𝗶𝗹𝗶𝘁𝘆 / 𝗠𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲𝘀 - Ensure high availability with redundancies and fault tolerance. Use tools like Kubernetes if needed.

𝟴. 𝗖𝗮𝗰𝗵𝗶𝗻𝗴 - Speed up reads with caching at various layers. Use appropriate eviction policies.

𝟵. 𝗣𝗿𝗼𝘅𝗶𝗲𝘀 - Use load balancers and reverse proxies for better availability and security.

𝟭𝟬. 𝗠𝗲𝘀𝘀𝗮𝗴𝗶𝗻𝗴 - Choose the right messaging protocols (TCP/UDP) and tools (Kafka, RabbitMQ) based on your needs.

You can check these resources for Coding interview Preparation

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Java practice set

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Software Developers => Let's understand, 𝐑𝐚𝐛𝐛𝐢𝐭𝐌𝐐 (Give it a read 👇)

RabbitMQ =>born in 2007 => a joint venture between LShift and CohesiveFT, aimed to provide an open-source, reliable message broker implementing the AMQP standard.

RabbitMQ is written in Erlang.

It is -

◾ an open-source message broker software that implements the Advanced Message Queuing Protocol (AMQP).

** AMQP => a binary protocol, meaning it encodes data in a compact binary format for efficient transmission over networks.

◾ a robust intermediary between different applications or components of a system, facilitating the exchange of messages in a reliable and scalable manner.

◾ known for its fault tolerance, concurrency and distributed systems capabilities.

◾ operating primarily on a 𝐩𝐮𝐬𝐡-𝐛𝐚𝐬𝐞𝐝 𝐦𝐨𝐝𝐞𝐥 for message delivery

📌 𝐂𝐨𝐫𝐞 𝐂𝐨𝐦𝐩𝐨𝐧𝐞𝐧𝐭𝐬
[1.] Producer
◾ An application that creates and sends messages to RabbitMQ.

[2.] Consumer
An application that receives messages from RabbitMQ.

[3.] Queue
◾ A named buffer where messages are stored.

[4.] Exchange
◾ The component that receives messages from producers and routes them to the appropriate queues based on specific rules.
◾ The heart of an exchange is its routing algorithm, which determines how messages are directed to queues.

Main exchange types -
◾ Direct - Matches the routing key of the message exactly with the binding key of a queue.
◾ Fanout - Broadcasts the message to all queues bound to the exchange.
◾ Topic - Uses wildcards (* and #) to match routing keys to binding keys.

[5.] Binding
A link between a queue and an exchange, specifying the routing criteria for messages.

📌 𝐇𝐨𝐰 𝐈𝐭 𝐖𝐨𝐫𝐤𝐬 𝐈𝐧𝐭𝐞𝐫𝐧𝐚𝐥𝐥𝐲?
1. The producer connects to RabbitMQ and publishes a message to an exchange.
2. The message includes routing information (e.g. => a routing key).
3. The exchange receives the message and examines the routing key.
4. Based on its configuration and bindings, the exchange determines which queues should receive the message.
5. The message is delivered to the designated queues, where it waits to be consumed.
6. Consumers connect to RabbitMQ and subscribe to specific queues.
7. When a message becomes available in the queue, RabbitMQ delivers it to one of the subscribed consumers.
8. After a consumer processes a message, it sends an acknowledgment to RabbitMQ, confirming that the message was successfully received and processed.
9. If no acknowledgment is received within a specified time, RabbitMQ can redeliver the message to another consumer.

📌 𝐅𝐥𝐨𝐰 𝐂𝐨𝐧𝐭𝐫𝐨𝐥
1. RabbitMQ uses credit-based flow control to prevent consumers from being overwhelmed with messages.
2. Consumers request a certain number of messages (credit) from the broker, and the broker delivers messages up to that limit.
3. When the consumer acknowledges a message, it receives additional credit, allowing the broker to send more messages.

Best DSA RESOURCES: https://topmate.io/coding/886874

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Commonly asked System Design CONCEPT BASED interview topics -

1. Horizontal vs Vertical Partitioning
2. Apache Kafka
3. Rate Limiter
4. JWT vs OAuth vs SAML
5. Single Sign-On (SSO)
6. Microservices vs Monolithic Architecture
7. Reverse Proxy vs Forward Proxy
8. CAP Theorem
9. Global Scale System Design
10. Efficient Caching Strategy

To learn these topics in detail go through the post:

You can check these resources for Coding interview Preparation

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𝗚𝗶𝘁 𝗘𝘀𝘀𝗲𝗻𝘁𝗶𝗮𝗹𝘀: 𝗬𝗼𝘂𝗿 𝗰𝗵𝗲𝗮𝘁 𝘀𝗵𝗲𝗲𝘁 𝗳𝗼𝗿 𝗺𝗮𝘀𝘁𝗲𝗿𝗶𝗻𝗴 𝘃𝗲𝗿𝘀𝗶𝗼𝗻 𝗰𝗼𝗻𝘁𝗿𝗼𝗹 👨💻


Whether you're a seasoned developer or just starting out, Git is an essential tool for seamless collaboration and efficient workflows. Here's a quick recap of the most common Git commands to keep you on track:

✨𝗚𝗲𝘁𝘁𝗶𝗻𝗴 𝗦𝘁𝗮𝗿𝘁𝗲𝗱:
git init: Initializes a new Git repository.
git clone <repo_url>: Clones an existing repository to your local machine.

📄𝗧𝗿𝗮𝗰𝗸𝗶𝗻𝗴 𝗖𝗵𝗮𝗻𝗴𝗲𝘀:
git status: Checks the status of files in your working directory.
git add <file> or git add .: Stages files for commit.

✅𝗖𝗼𝗺𝗺𝗶𝘁𝘁𝗶𝗻𝗴 𝗪𝗼𝗿𝗸:
git commit -m "message": Commits staged changes with a denoscriptive message.

🔀𝗕𝗿𝗮𝗻𝗰𝗵𝗶𝗻𝗴 𝗮𝗻𝗱 𝗠𝗲𝗿𝗴𝗶𝗻𝗴:
git branch: Lists existing branches.
git branch <new_branch>: Creates a new branch.
git checkout <branch>: Switches to a different branch.
git merge <branch>: Merges changes from one branch into another.
git checkout -b <new_branch>: Creates and switches to a new branch.

👨💻𝗥𝗲𝗺𝗼𝘁𝗲 𝗖𝗼𝗹𝗹𝗮𝗯𝗼𝗿𝗮𝘁𝗶𝗼𝗻:
git remote -v: Lists remote repositories.
git fetch origin <branch>: Fetches changes from a remote branch.
git merge origin/<branch>: Merges fetched changes into the current branch.
git push origin <branch>: Pushes local changes to a remote branch.

🔎𝗧𝗿𝗮𝗰𝗸𝗶𝗻𝗴 𝗛𝗶𝘀𝘁𝗼𝗿𝘆:
git log: Shows a list of commits.
git log --oneline: Displays a condensed commit history.

⏪𝗨𝗻𝗱𝗼𝗶𝗻𝗴 𝗠𝗶𝘀𝘁𝗮𝗸𝗲𝘀:
git revert <commit>: Reverses a specific commit.
git reset --hard HEAD: Resets the working directory to the last commit (use with caution!).

𝗧𝗮𝗴𝗴𝗶𝗻𝗴 𝗠𝗶𝗹𝗲𝘀𝘁𝗼𝗻𝗲𝘀:
git tag: Lists existing tags.
git tag -a v1.0 -m "tag": Creates a new tag for a specific commit.

⚙𝗖𝗼𝗻𝗳𝗶𝗴𝘂𝗿𝗮𝘁𝗶𝗼𝗻:
git config --global user. name "name": Sets your global Git username.
git config --global user. email "email": Sets your global Git email.

Is DSA important for interviews?

Yes, DSA (Data Structures and Algorithms) is very important for interviews, especially for software engineering roles.

I often get asked, What do I need to start learning DSA?

Here's the roadmap for getting started with Data Structures and Algorithms (DSA):

𝗣𝗵𝗮𝘀𝗲 𝟭: 𝗙𝘂𝗻𝗱𝗮𝗺𝗲𝗻𝘁𝗮𝗹𝘀
1. Introduction to DSA
- Understand what DSA is and why it's important.
- Overview of complexity analysis (Big O notation).

2. Complexity Analysis
- Time Complexity
- Space Complexity

3. Basic Data Structures
- Arrays
- Linked Lists
- Stacks
- Queues

4. Basic Algorithms
- Sorting (Bubble Sort, Selection Sort, Insertion Sort)
- Searching (Linear Search, Binary Search)

5. OOP (Object-Oriented Programming)

𝗣𝗵𝗮𝘀𝗲 𝟮: 𝗜𝗻𝘁𝗲𝗿𝗺𝗲𝗱𝗶𝗮𝘁𝗲 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀
1. Two Pointers Technique
- Introduction and basic usage
- Problems: Pair Sum, Triplets, Sorted Array Intersection etc..

2. Sliding Window Technique
- Introduction and basic usage
- Problems: Maximum Sum Subarray, Longest Substring with K Distinct Characters, Minimum Window Substring etc..

3. Line Sweep Algorithms
- Introduction and basic usage
- Problems: Meeting Rooms II, Skyline Problem

4. Recursion

5. Backtracking

6. Sorting Algorithms
- Merge Sort
- Quick Sort

7. Data Structures
- Hash Tables
- Trees (Binary Trees, Binary Search Trees)
- Heaps

𝗣𝗵𝗮𝘀𝗲 𝟯: 𝗔𝗱𝘃𝗮𝗻𝗰𝗲𝗱 𝗖𝗼𝗻𝗰𝗲𝗽𝘁𝘀
1. Graph Algorithms
- Graph Representation (Adjacency List, Adjacency Matrix)
- BFS (Breadth-First Search)
- DFS (Depth-First Search)
- Shortest Path Algorithms (Dijkstra's, Bellman-Ford)
- Minimum Spanning Tree (Kruskal's, Prim's)

2. Dynamic Programming
- Basic Problems (Fibonacci, Knapsack etc..)
- Advanced Problems (Longest Increasing Subsea mice, Matrix Chain Subsequence, Multiplication etc..)

3. Advanced Trees
- AVL Trees
- Red-Black Trees
- Segment Trees
- Trie

𝗣𝗵𝗮𝘀𝗲 𝟰: 𝗣𝗿𝗮𝗰𝘁𝗶𝗰𝗲 𝗮𝗻𝗱 𝗔𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻
1. Competitive Programming Platforms: LeetCode, Codeforces, HackerRank, CodeChef Solve problems daily

2. Mock Interviews
- Participate in mock interviews to simulate real interview scenarios.
- DSA interviews assess your ability to break down complex problems into smaller steps.

Best DSA RESOURCES: https://topmate.io/coding/886874

All the best 👍👍

𝗰𝗵𝗲𝗮𝘁𝘀𝗵𝗲𝗲𝘁 𝗳𝗼𝗿 𝗔𝗟𝗟 𝗲𝘀𝘀𝗲𝗻𝘁𝗶𝗮𝗹 𝗴𝗶𝘁 𝗰𝗼𝗺𝗺𝗮𝗻𝗱𝘀:

0. 𝗴𝗶𝘁 𝗶𝗻𝗶𝘁: Initializes a new Git repository.
1. 𝗴𝗶𝘁 𝗰𝗹𝗼𝗻𝗲 [𝘂𝗿𝗹]: Creates a local copy of a remote repository.
2. 𝗴𝗶𝘁 𝘀𝘁𝗮𝘁𝘂𝘀: Displays the state of the working directory and staging area.
3. 𝗴𝗶𝘁 𝗮𝗱𝗱 [𝗳𝗶𝗹𝗲]: Adds a file to the staging area.
4. 𝗴𝗶𝘁 𝗿𝗲𝘀𝗲𝘁 [𝗳𝗶𝗹𝗲]: Unstages a file while retaining the changes.
5. 𝗴𝗶𝘁 𝗱𝗶𝗳𝗳 --𝘀𝘁𝗮𝗴𝗲𝗱: Shows differences between the staging area and the last commit.
6. 𝗴𝗶𝘁 𝗰𝗼𝗺𝗺𝗶𝘁 -𝗺 "[𝗺𝗲𝘀𝘀𝗮𝗴𝗲]": Records staged changes with a denoscriptive message.
7. 𝗴𝗶𝘁 𝗯𝗿𝗮𝗻𝗰𝗵: Lists all local branches.
8. 𝗴𝗶𝘁 𝗰𝗵𝗲𝗰𝗸𝗼𝘂𝘁 -𝗯 [𝗻𝗮𝗺𝗲]: Creates and switches to a new branch.
9. 𝗴𝗶𝘁 𝗹𝗼𝗴: Displays commit history.
10. 𝗴𝗶𝘁 𝗿𝗲𝗺𝗼𝘁𝗲 𝗮𝗱𝗱 [𝗿𝗲𝗳] [𝘂𝗿𝗹]: Adds a new remote repository.
11. 𝗴𝗶𝘁 𝗽𝘂𝘀𝗵 [𝗮𝗹𝗶𝗮𝘀] [𝗯𝗿𝗮𝗻𝗰𝗵]: Uploads local branch commits to a remote repository.
12. 𝗴𝗶𝘁 𝗽𝘂𝗹𝗹: Fetches and merges changes from the remote to the local repository.
13. 𝗴𝗶𝘁 𝘀𝘁𝗮𝘀𝗵: Temporarily stores modified tracked files.
14. 𝗴𝗶𝘁 𝘀𝘁𝗮𝘀𝗵 𝗽𝗼𝗽: Restores the most recently stashed files.
15. 𝗴𝗶𝘁 𝘀𝘁𝗮𝘀𝗵 𝗱𝗿𝗼𝗽: Discards the most recently stashed changeset.
16. 𝗴𝗶𝘁 𝗿𝗲𝗯𝗮𝘀𝗲 [𝗯𝗿𝗮𝗻𝗰𝗵]: Reapplies commits on top of another base tip.
17. 𝗴𝗶𝘁 𝗿𝗲𝗯𝗮𝘀𝗲 -𝗶 𝗛𝗘𝗔𝗗~<𝗻>: Starts an interactive rebase for the last n commits.
18. 𝗴𝗶𝘁 𝗿𝗲𝘀𝗲𝘁 --𝗵𝗮𝗿𝗱 [𝗰𝗼𝗺𝗺𝗶𝘁]: Resets the working directory to a specified commit.
19. 𝗴𝗶𝘁 𝗹𝗼𝗴 𝗯𝗿𝗮𝗻𝗰𝗵𝗕..𝗯𝗿𝗮𝗻𝗰𝗵𝗔: Shows commits on branchA that are not on branchB.
20. 𝗴𝗶𝘁 𝗱𝗶𝗳𝗳 𝗯𝗿𝗮𝗻𝗰𝗵𝗕...𝗯𝗿𝗮𝗻𝗰𝗵𝗔: Displays differences between two branches.
21. 𝗴𝗶𝘁 𝘀𝗵𝗼𝘄 [𝗦𝗛𝗔]: Shows the changes in a specific commit.
22. 𝗴𝗶𝘁 𝗰𝗼𝗻𝗳𝗶𝗴 --𝗴𝗹𝗼𝗯𝗮𝗹 𝗰𝗼𝗿𝗲.𝗲𝘅𝗰𝗹𝘂𝗱𝗲𝘀𝗳𝗶𝗹𝗲 [𝗳𝗶𝗹𝗲]: Sets up a global file for ignoring files.

Best DSA RESOURCES: https://topmate.io/coding/886874

All the best 👍👍

Important Topics for DSA

1. Week 1: Foundation
- Arrays & Linked Lists: Understand how to store and manage a list of elements.
- Stacks & Queues: Learn the Last-In-First-Out (LIFO) and First-In-First-Out (FIFO) principles.
- Searching & Sorting Techniques: Master basic algorithms for finding and organizing data.

2. Week 2: Intermediate
- Trees & Graphs: Study hierarchical and network data structures.
- Hashing & Hash Tables: Learn efficient methods for data retrieval.
- Dynamic Programming: Break problems into simpler sub-problems and solve them.

3. Week 3: Advanced
- Advanced Tree & Graph Algorithms: Delve deeper into complex traversal techniques.
- Heaps & Priority Queues: Understand specialized data structures for efficient prioritization.
- Backtracking & Recursion: Tackle problems with recursive solutions.

4. Week 4: DSA Hackathon
- Participate in coding challenges to solidify your learning and apply your skills.

Few Tips for Mastering DSA

1. Start Simple: Begin with easy problems and gradually move to more complex ones.
2. Practice Regularly: Consistency is key. Solve problems daily to improve your skills.
3. Understand Concepts: Don’t just memorize algorithms. Understand how and why they work.
4. Use Resources: Take advantage of online tutorials, courses, and coding platforms.
5. Join Communities: Engage with coding communities for support, motivation, and knowledge sharing.
6. Participate in Challenges: Join hackathons and coding contests to test your skills in real scenarios.

Best DSA RESOURCES: https://topmate.io/coding/886874

All the best 👍👍

DSA + DEVELOPMENT (Daily Schedule) 👨🏻‍💻

Morning:
- 9:00 AM - 10:30 AM: DSA Practice
- 10:30 AM - 11:00 AM: Break
- 11:00 AM - 12:30 PM: DSA Study/Review

Lunch:
- 12:30 PM - 1:30 PM: Lunch and Rest

Afternoon:
- 1:30 PM - 3:00 PM: MERN Development
- 3:00 PM - 3:30 PM: Break
- 3:30 PM - 5:00 PM: MERN Development

Evening:
- 5:00 PM - 6:00 PM: Review and Debug
- 6:00 PM - 7:00 PM: Dinner and Rest

Late Evening:
- 7:00 PM - 8:00 PM: Personal Development
- 8:00 PM - 9:00 PM: Reflect and Plan

Best DSA RESOURCES: https://topmate.io/coding/886874

All the best 👍👍

Java Developer Interview ❤
It'll gonna be super helpful for YOU

𝗧𝗼𝗽𝗶𝗰 𝟭: 𝗣𝗿𝗼𝗷𝗲𝗰𝘁 𝗳𝗹𝗼𝘄 𝗮𝗻𝗱 𝗮𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗲
- Please tell me about your project and its architecture, Challenges faced?
- What was your role in the project? Tech Stack of project? why this stack?
- Problem you solved during the project? How collaboration within the team?
- What lessons did you learn from working on this project?
- If you could go back, what would you do differently in this project?

𝗧𝗼𝗽𝗶𝗰 𝟮: 𝗖𝗼𝗿𝗲 𝗝𝗮𝘃𝗮
- String Concepts/Hashcode- Equal Methods
- Immutability
- OOPS concepts
- Serialization
- Collection Framework
- Exception Handling
- Multithreading
- Java Memory Model
- Garbage collection

Tech Community
👉 t.me/Java_Programming_Notes

𝗧𝗼𝗽𝗶𝗰 𝟯: 𝗝𝗮𝘃𝗮-𝟴/𝗝𝗮𝘃𝗮-𝟭𝟭/𝗝𝗮𝘃𝗮𝟭𝟳
- Java 8 features
- Default/Static methods
- Lambda expression
- Functional interfaces
- Optional API
- Stream API
- Pattern matching
- Text block
- Modules

𝗧𝗼𝗽𝗶𝗰 𝟰: 𝗦𝗽𝗿𝗶𝗻𝗴 𝗙𝗿𝗮𝗺𝗲𝘄𝗼𝗿𝗸, 𝗦𝗽𝗿𝗶𝗻𝗴-𝗕𝗼𝗼𝘁, 𝗠𝗶𝗰𝗿𝗼𝘀𝗲𝗿𝘃𝗶𝗰𝗲, 𝗮𝗻𝗱 𝗥𝗲𝘀𝘁 𝗔𝗣𝗜
- Dependency Injection/IOC, Spring MVC
- Configuration, Annotations, CRUD
- Bean, Scopes, Profiles, Bean lifecycle
- App context/Bean context
- AOP, Exception Handler, Control Advice
- Security (JWT, Oauth)
- Actuators
- WebFlux and Mono Framework
- HTTP methods
- JPA
- Microservice concepts
- Spring Cloud

𝗧𝗼𝗽𝗶𝗰 𝟱: 𝗛𝗶𝗯𝗲𝗿𝗻𝗮𝘁𝗲/𝗦𝗽𝗿𝗶𝗻𝗴-𝗱𝗮𝘁𝗮 𝗝𝗽𝗮/𝗗𝗮𝘁𝗮𝗯𝗮𝘀𝗲 (𝗦𝗤𝗟 𝗼𝗿 𝗡𝗼𝗦𝗤𝗟)
- JPA Repositories
- Relationship with Entities
- SQL queries on Employee department
- Queries, Highest Nth salary queries
- Relational and No-Relational DB concepts
- CRUD operations in DB
- Joins, indexing, procs, function

𝗧𝗼𝗽𝗶𝗰 𝟲: 𝗖𝗼𝗱𝗶𝗻𝗴
- DSA Related Questions
- Sorting and searching using Java API.
- Stream API coding Questions

Tech Jobs and Internships
t.me/getjobss

𝗧𝗼𝗽𝗶𝗰 𝟳: 𝗗𝗲𝘃𝗼𝗽𝘀 𝗾𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀 𝗼𝗻 𝗱𝗲𝗽𝗹𝗼𝘆𝗺𝗲𝗻𝘁 𝗧𝗼𝗼𝗹𝘀
- These types of topics are mostly asked by managers or leads who are heavily working on it, That's why they may grill you on DevOps/deployment-related tools, You should have an understanding of common tools like Jenkins, Kubernetes, Kafka, Cloud, and all.

𝗧𝗼𝗽𝗶𝗰𝘀 𝟴: 𝗕𝗲𝘀𝘁 𝗽𝗿𝗮𝗰𝘁𝗶𝗰𝗲
- The interviewer always wanted to ask about some design patterns, it may be Normal design patterns like singleton, factory, or observer patterns to know that you can use these in coding.

PDFs and Notes 📝
t.me/Java_Programming_Notes

Best Programming Resources: https://topmate.io/coding/886839

All the best 👍👍

𝐄𝐯𝐞𝐫𝐲 𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫 𝐌𝐮𝐬𝐭 𝐊𝐧𝐨𝐰 𝐭𝐡𝐞 𝐓𝐨𝐩 𝟕 𝐀𝐫𝐜𝐡𝐢𝐭𝐞𝐜𝐭𝐮𝐫𝐚𝐥 𝐏𝐚𝐭𝐭𝐞𝐫𝐧𝐬

An architectural pattern is a general, reusable solution to common problems in software design. It structures and organises software systems to address specific concerns like scalability, maintainability, flexibility, and efficiency.

1. Microservices Architecture:
Divides an app into small, independent services with APIs.
Example: Netflix - separate services for user management, content streaming, and recommendations.

2. Layered Architecture:
Divides an app into layers (presentation, logic, data) for specific functions.
Example: JavaEE apps - distinct layers for UI, business logic, and data access.

3. Event-Driven Architecture:
Components communicate through events for loose coupling.
Example: Airbnb uses Apache Kafka for real-time event processing like booking requests.

4. Model-View-Controller (MVC) Architecture:
Splits an app into Model (data), View (UI), and Controller (logic).
Example: Ruby on Rails apps - separation of data, interface, and user input handling.

5. Master-Slave Architecture:
One master coordinates multiple slaves' tasks.
Example: Database replication - master for writes, slaves for reads, as seen in many systems.

6. Monolithic Architecture:
Entire app bundled together as a single unit.
Example: Traditional enterprise software - all features in a single executable.

7. Service-Oriented Architecture (SOA):
App composed of reusable, loosely coupled services.
Example: Salesforce - integrated or standalone sales, support, and marketing services.

Each pattern offers unique advantages and trade-offs, depending on the project's requirements and complexities.

Best DSA RESOURCES: https://topmate.io/coding/886874

All the best 👍👍