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Java Interview Preparation for Beginners
Java Interview Quiz: Fundamentals, Strings and OOP

Step 12 of 38 · Java Interview Preparation for Beginners · Stage 2: Object-oriented programming

Java Interview Quiz: Fundamentals, Strings and OOP

Ten interview-style questions on the JVM, pass-by-value, the Integer cache, strings, overriding versus hiding, abstract classes and interfaces.

Easy10 questions· 0 attempts

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In this collection

Stage 1: Roadmap and language fundamentals
1Java Interview Roadmap for Beginners: A 30-Day PlanArticle
2JDK vs JRE vs JVM: How Java Code RunsArticle
3Java Data Types, Pass-by-Value and AutoboxingArticle

4

Java Strings: Immutability, the String Pool and StringBuilder

Article

5String Pool Demo: == versus equals()javaSnippet

6Reverse a String and Check a PalindromejavaSnippet

7Character Frequency Counter with a HashMapjavaSnippet

Stage 2: Object-oriented programming

8OOP in Java: Inheritance, Polymorphism and AbstractionArticle

9Overriding vs Hiding: Static Methods, Fields and Private MethodsjavaSnippet

10equals() and hashCode(): The Contract and Why It MattersArticle

11equals() and hashCode() for a HashMap KeyjavaSnippet

12Java Interview Quiz: Fundamentals, Strings and OOP10 questions · Easy · 15 minQuiz

Stage 3: Collections, generics and exceptions

13Java Collections: List, Set, Map and How HashMap WorksArticle

14Java Generics: Type Erasure, Wildcards and PECSArticle

15Exception Handling in Java: Checked vs Unchecked and try-with-resourcesArticle

16try-with-resources: Automatic Closing in Reverse OrderjavaSnippet

17LRU Cache with LinkedHashMapjavaSnippet

18Java Interview Quiz: Collections, Generics and Exceptions10 questions · Medium · 20 minQuiz

Stage 4: Modern Java and streams

19Modern Java: Lambdas, Optional, Records and Sealed ClassesArticle

20Java Streams API: Lazy Pipelines, map vs flatMap and CollectorsArticle

21Group and Aggregate Employees by Department with StreamsjavaSnippet

22Second Highest Salary with Streams (and the Nth Highest)javaSnippet

23Collectors.toMap and Duplicate KeysjavaSnippet

Stage 5: Concurrency and the JVM

24Java Threads: start vs run, Race Conditions, synchronized and volatileArticle

25Thread-Safe Counter: synchronized, AtomicInteger and LongAdderjavaSnippet

26Executors, CompletableFuture and Virtual Threads in JavaArticle

27Java Memory and Garbage Collection: Stack, Heap and Common ErrorsArticle

28Java Interview Quiz: Modern Java, Streams and Concurrency10 questions · Medium · 20 minQuiz

Stage 6: Databases, Spring and testing

29JDBC for Beginners: PreparedStatement, Transactions and SQL InjectionArticle

30SOLID, Dependency Injection and Spring Boot Basics for Java InterviewsArticle

31Unit Testing in Java: JUnit 5 and Mockito for BeginnersArticle

Stage 7: Interview practice

3225 Java Mistakes Freshers Make in Interviews (and How to Avoid Them)Article

3335 Java Coding Interview Problems for Freshers with Tested SolutionsArticle

34Two Sum with a HashMapjavaSnippet

35Balanced Parentheses with a StackjavaSnippet

36Longest Substring Without Repeating CharactersjavaSnippet

37Top 50 Java Interview Questions and Answers for FreshersArticle

38Java Interview Quiz: JVM, JDBC, Spring and Coding10 questions · Medium · 20 minQuiz