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

2. Write a Java program to declare and initialize a variable of each primitive data type.

3. Write a Java program to swap two numbers using a temporary variable.

4. Write a Java program to swap two numbers without using a temporary variable.

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

6. Write a Java program to find the largest of three numbers.

7. Write a Java program to print all natural numbers from 1 to 100.

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

9. Write a Java program to find the sum of digits of a number.

10. Write a Java program to reverse a number.

11. Write a Java program to check if a number is a palindrome.

12. Write a Java program to find the GCD of two numbers.

13. Write a Java program to find the LCM of two numbers.

14. Write a Java program to check if a number is prime.

15. Write a Java program to print the Fibonacci series up to a given number.

16. Write a Java program to find the sum of the first n natural numbers.

17. Write a Java program to find the sum of the first n odd numbers.

18. Write a Java program to find the sum of the first n even numbers.

19. Write a Java program to count the number of digits in a number.

20. Write a Java program to print the multiplication table of a given number.

21. Write a Java program to find the average of n numbers.

22. Write a Java program to find the second largest number in an array.

23. Write a Java program to find the sum of elements in an array.

24. Write a Java program to find the maximum and minimum elements in an array.

25. Write a Java program to sort an array in ascending order.

26. Write a Java program to sort an array in descending order.

27. Write a Java program to search for an element in an array.

28. Write a Java program to find the frequency of elements in an array.

29. Write a Java program to remove duplicates from an array.

30. Write a Java program to merge two arrays.

31. Write a Java program to find the length of a string.

32. Write a Java program to reverse a string.

33. Write a Java program to check if a string is a palindrome.

34. Write a Java program to convert a string to uppercase.

35. Write a Java program to convert a string to lowercase.

36. Write a Java program to find the number of vowels in a string.

37. Write a Java program to find the number of consonants in a string.

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

39. Write a Java program to count the occurrence of each character in a string.

40. Write a Java program to find the largest and smallest word in a string.

41. Write a Java program to replace spaces with hyphens in a string.

42. Write a Java program to check if a string contains only digits.

43. Write a Java program to convert a binary number to decimal.

44. Write a Java program to convert a decimal number to binary.

45. Write a Java program to convert a binary number to hexadecimal.

46. Write a Java program to convert a hexadecimal number to binary.

47. Write a Java program to check if a year is a leap year.

48. Write a Java program to calculate the area and circumference of a circle.

49. Write a Java program to calculate the area and perimeter of a rectangle.

50. Write a Java program to calculate the area and perimeter of a triangle.