Recently, I found out that many folks try to learn everything in java, by watching 100+ or even 200+ hours of content.

Instead, I’d strongly recommend focusing on the essentials first. Once you master these, you can expand further, most of the interview q&a will come from the below list.

If you’re an SDET or preparing for coding interviews, start with these key Java concepts:

𝟭. 𝗦𝘁𝗿𝗶𝗻𝗴𝘀

- Understanding immutability and memory usage

- Essential methods (length(), charAt(), substring(), replace(), split())

- StringBuilder vs. StringBuffer (performance impact)

- String comparison (== vs .equals())

- Regular expressions (regex) for pattern matching

𝟮. 𝗔𝗿𝗿𝗮𝘆𝘀

- Declaring and initializing arrays

- One-dimensional vs. multi-dimensional arrays

- Searching and sorting techniques

- Iterating through arrays efficiently

- Arrays vs. Lists (key differences)

𝟯. 𝗟𝗶𝘀𝘁𝘀

- When to use ArrayList vs. LinkedList

- Common operations (adding, removing, searching elements)

- Sorting lists using Comparator and Comparable

- Converting between arrays and lists

- Efficient iteration techniques

𝟰. 𝗠𝗮𝗽𝘀

- Choosing the right map: HashMap vs. LinkedHashMap vs. TreeMap

- Performing key-value operations

- Different ways to iterate over maps

- Handling null keys and values properly

- How hashing works in HashMap

𝟱. 𝗢𝗕𝗝𝗘𝗖𝗧-𝗢𝗥𝗜𝗘𝗡𝗧𝗘𝗗 𝗣𝗥𝗢𝗚𝗥𝗔𝗠𝗠𝗜𝗡𝗚 (𝗢𝗢𝗣𝗦)

- Four pillars: Encapsulation, Inheritance, Polymorphism, Abstraction

- Understanding Class vs. Object

- Method overloading vs. method overriding

- Interfaces vs. Abstract classes

- Static vs. instance methods and variables

- Design patterns (Singleton, Factory, etc.)

Focus on these first. Once you master them, dive deeper into advanced topics. But don’t get stuck in tutorial hell—practicing and applying concepts is what really matters!

------------

👉 Learn more on my YouTube Channel: https://www.youtube.com/@automatewithsidharth
👉  LinkedIn: https://www.linkedin.com/in/sidharth-shukla-77b53145/

------------

#sidpost #java #testing #career #sdet #testautomation #automation #softwaretesting #qualityassurance #java #qa #qaautomation