Core Java practical practice questions

SK Institute Tutorial Link

• Tutorial Link- Visit now [<- Click here]

 Here’s a comprehensive list of Core Java practical practice questions to help you strengthen your Java programming skills:

---

Basic Java Programs

1. Write a program to print "Hello, World!"

2. Write a program to add two numbers.

3. Write a program to swap two numbers (with & without a temporary variable).

4. Write a program to check if a number is even or odd.

5. Write a program to find the largest of three numbers.

6. Write a program to check if a number is prime.

7. Write a program to print Fibonacci series up to n terms.

8. Write a program to find the factorial of a number.

9. Write a program to reverse a number.

10. Write a program to check if a number is a palindrome.

---

String Manipulation

11. Write a program to reverse a string.

12. Write a program to check if a string is a palindrome.

13. Write a program to count vowels and consonants in a string.

14. Write a program to remove all whitespaces from a string.

15. Write a program to count the occurrences of a character in a string.

16. Write a program to convert a string to uppercase/lowercase.

17. Write a program to find the length of a string without using length().

18. Write a program to concatenate two strings without using +.

19. Write a program to check if two strings are anagrams.

20. Write a program to find the first non-repeated character in a string.

---

Array & Matrix Problems

21. Write a program to find the largest & smallest element in an array.

22. Write a program to sort an array (ascending/descending).

23. Write a program to reverse an array.

24. Write a program to find the sum of all elements in an array.

25. Write a program to find the second-largest number in an array.

26. Write a program to merge two sorted arrays.

27. Write a program to remove duplicates from an array.

28. Write a program to perform matrix addition/multiplication.

29. Write a program to find the transpose of a matrix.

30. Write a program to check if a matrix is symmetric.

---

OOPs Concepts

31. Create a Student class with attributes (name, rollNo, marks) and methods to display details.

32. Implement inheritance (Animal → Dog, Cat).

33. Demonstrate method overloading (compile-time polymorphism).

34. Demonstrate method overriding (runtime polymorphism).

35. Create an abstract class Shape with abstract method area() (implement in Circle, Rectangle).

36. Create an interface Drawable with method draw() (implement in Pen, Pencil).

37. Write a program to show encapsulation (private fields with getters/setters).

38. Implement a singleton class.

39. Create a BankAccount class with deposit(), withdraw(), and exception handling for insufficient balance.

40. Demonstrate the use of final keyword (variable, method, class).

---

Exception Handling

41. Write a program to handle ArithmeticException (division by zero).

42. Write a program to handle ArrayIndexOutOfBoundsException.

43. Write a program to handle NullPointerException.

44. Create a custom exception InvalidAgeException (throw if age < 18).

45. Demonstrate try-catch-finally with a file read operation.

---

Collections Framework

46. Write a program to sort an ArrayList of strings.

47. Write a program to remove duplicates from an ArrayList.

48. Write a program to iterate over a HashMap and print key-value pairs.

49. Write a program to check if a LinkedList is empty.

50. Write a program to reverse a LinkedList.

51. Write a program to find the frequency of words in a string using HashMap.

52. Write a program to sort a HashSet.

53. Write a program to compare two ArrayLists for equality.

54. Write a program to convert an array to ArrayList and vice versa.

55. Implement a PriorityQueue for custom objects (e.g., Employee by salary).

---

File Handling

56. Write a program to read a file and count the number of lines.

57. Write a program to write data to a file.

58. Write a program to copy contents from one file to another.

59. Write a program to count the occurrences of a word in a file.

60. Write a program to append text to an existing file.

---

Multithreading

61. Write a program to create a thread by extending Thread class.

62. Write a program to create a thread by implementing Runnable.

63. Write a program to demonstrate thread synchronization.

64. Write a program to simulate a deadlock scenario.

65. Write a program to print even and odd numbers using two threads.

---

Miscellaneous

66. Write a program to print current date and time.

67. Write a program to convert String to Date.

68. Write a program to generate random numbers.

69. Write a program to compute the sum of digits until a single digit is obtained.

70. Write a program to implement a basic calculator (+, -, *, /).

---

Difficulty Level: Advanced

71. Implement a LRU (Least Recently Used) cache.

72. Write a program to serialize and deserialize an object.

73. Implement a producer-consumer problem using wait() and notify().

74. Write a program to find all permutations of a string.

75. Implement a binary search algorithm.

---

These questions cover Core Java fundamentals, OOPs, Collections, Exception Handling, File I/O, and Multithreading.
Tip: Start with basics, then move to advanced topics.