Java Interview Cheat Sheet

1. What are the main features of Java?

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2. What is the difference between JDK, JRE, and JVM?

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3. What is the difference between Java and C++?

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4. Explain object-oriented programming concepts in Java.

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5. What is a class and an object in Java?

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6. What are primitive and reference data types?

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7. What is the difference between method overloading and overriding?

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8. What are constructors in Java?

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9. What is the difference between this and super keywords?

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10. What are access modifiers in Java?

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11. What is the difference between static and instance members?

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12. What is the difference between final, finally, and finalize?

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13. What is garbage collection in Java?

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14. What are Java packages and their benefits?

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15. What is an interface and how is it different from an abstract class?

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16. What are Java exceptions?

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17. What is the difference between == and equals()?

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18. What are wrapper classes and autoboxing/unboxing?

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19. What are Java generics and why are they used?

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20. What are Java collections?

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21. What are Java 8 Lambda expressions?

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22. Explain functional interfaces.

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23. What is the Streams API in Java?

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24. Difference between intermediate and terminal operations in Streams.

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25. Explain Optional in Java.

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26. What is method reference in Java 8?

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27. Difference between map and flatMap in Streams.

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28. Explain Collectors in Streams API.

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29. What are default and static methods in interfaces?

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30. Explain the difference between sequential and parallel streams.

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31. How do Java 8 enhancements improve collection processing?

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32. How do you handle exceptions in lambda expressions?

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33. Difference between Predicate, Function, Consumer, and Supplier.

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34. How do streams differ from traditional iteration?

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35. How do you group elements using Collectors?

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36. Explain the use of peek() in streams.

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37. Difference between Optional.map() and Optional.flatMap().

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38. Difference between immutable and unmodifiable collections.

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39. How do you handle nulls in streams?

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40. What are the new Stream-related features in Java 9+?

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41. Explain the four pillars of OOP in Java.

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42. Difference between abstract classes and interfaces.

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43. What is method overriding vs method overloading?

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44. How does the super keyword work?

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45. Explain constructor chaining in Java.

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46. What are static blocks and static methods?

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47. Difference between final, finally, and finalize.

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48. Explain Java exception hierarchy.

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49. How is multiple inheritance handled in Java?

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50. Explain object cloning in Java.

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