📋 Section 20 · 27 questions

Records and Generics

27 interview questions and answers in the Records and Generics section.

📄 Source Markdown

Questions in this section

  1. What is Record in Java and Since Which Version are They Available
  2. What Are the Main Differences Between Record and Regular Class
  3. Can You Inherit From Record or Have Record Inherit From Another Class
  4. Can You Add Additional Methods to a Record
  5. What Methods are Automatically Generated for a Record
  6. Can You Override Constructor in Record
  7. What is Compact Constructor in Record
  8. Can You Declare Static Fields and Methods in Record
  9. Are Record Fields final
  10. Can you use Record as a key in HashMap
  11. What are Generics in Java
  12. What are the advantages of using Generics
  13. What is type erasure
  14. Can you create an array of generic type
  15. What are bounded type parameters
  16. What is the difference between extends T and super T
  17. What is PECS (Producer Extends Consumer Super)
  18. Can you use primitive types as generic parameters
  19. What are raw types and why should you avoid them
  20. What happens when trying to create an instance of generic type via new T()
  21. What is the difference between List wildcard and List Object
  22. Can you overload methods that differ only in generic parameters
  23. What is recursive type bound
  24. How do Generics work with inheritance
  25. What are bridge methods and why are they needed
  26. Can you use multiple bounds for a single type parameter
  27. How to implement Singleton pattern with Record

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27 essential questions and deep-dive technical analyses for Junior 🟢, Middle 🟡, and Senior 🔴 Java Engineers and Architects.

📋 Table of Contents

# Question Difficulty
01 What is Record in Java and Since Which Version are They Available ⭐
02 What Are the Main Differences Between Record and Regular Class ⭐
03 Can You Inherit From Record or Have Record Inherit From Another Class ⭐⭐
04 Can You Add Additional Methods to a Record ⭐
05 What Methods are Automatically Generated for a Record ⭐
06 Can You Override Constructor in Record ⭐⭐
07 What is Compact Constructor in Record ⭐⭐
08 Can You Declare Static Fields and Methods in Record ⭐
09 Are Record Fields final ⭐
10 Can You Use Record as a Key in HashMap ⭐⭐
11 What Are Generics in Java ⭐
12 What Are the Advantages of Using Generics ⭐
13 What is Type Erasure ⭐⭐
14 Can You Create an Array of Generic Type ⭐⭐
15 What Are Bounded Type Parameters ⭐⭐
16 What is the Difference Between extends T and super T ⭐⭐
17 What is PECS (Producer Extends Consumer Super) ⭐⭐
18 Can You Use Primitive Types as Generic Parameters ⭐
19 What Are Raw Types and Why Should You Avoid Them ⭐⭐
20 What Happens When Trying to Create an Instance of Generic Type via new T() ⭐⭐
21 What is the Difference Between List wildcard and List Object ⭐⭐
22 Can You Overload Methods That Differ Only in Generic Parameters ⭐⭐
23 What is Recursive Type Bound ⭐⭐⭐
24 How Do Generics Work with Inheritance ⭐⭐
25 What Are Bridge Methods and Why Are They Needed ⭐⭐⭐
26 Can You Use Multiple Bounds for a Single Type Parameter ⭐⭐
27 How to Implement Singleton Pattern with Record ⭐⭐

🗺️ Topic Dependency Map

                    ┌──────────────────────────────────────────┐
                    │      JAVA RECORDS (01-10, 27)            │
                    │   01-02. What is Record & Class Diff     │
                    │   03, 08-09. final, static, inheritance  │
                    │   04-05. Methods & Auto-Generators       │
                    │   06-07. Canonical & Compact Constructor │
                    │   10. HashMap Invariants & Record Keys   │
                    │   27. Singleton Record Trade-offs        │
                    └──────────────────┬───────────────────────┘
                                       │
            ┌──────────────────────────┴──────────────────────────┐
            ▼                                                     ▼
    ┌──────────────────────────┐                        ┌──────────────────────────┐
    │ GENERICS FOUNDATIONS     │                        │ ADVANCED TYPE SYSTEM     │
    │ (11-14, 18-20)           │                        │ & VARIANCE (15-17, 21-26)│
    │ 11-12. Typesafe Generics │                        │ 15, 26. Bounds (& Interf)│
    │ 13. Type Erasure Underhood                        │ 16-17. extends, super,   │
    │ 14. Generic Array Ban    │                        │        PECS Principle    │
    │ 18. Primitives & Valhalla│                        │ 21. List<?> vs List<Obj> │
    │ 19. Raw Types Danger     │                        │ 22. Erasure Overload Ban │
    │ 20. new T() Elimination  │                        │ 23. Recursive Bound <T>  │
    └──────────────────────────┘                        │ 24-25. Invariance, Covar,│
                                                        │        Bridge Methods    │
                                                        └──────────────────────────┘

🎯 Recommended Study Tracks

🟢 Junior Track (Core Fundamentals)

🟡 Middle Track (Type Erasure & Record Constructors)

🔴 Senior Track (Bridge Methods, Recursive Bounds & JVM Internals)