Practice 70 Java String Programming Questions

Practice 70 Java String Programming Questions

Q1. Write a Java program to check if a string is empty.
  - Input: "Hello"
  - Expected Output: False

Q2. Write a Java program to reverse a string.
  - Input: "Hello"
  - Expected Output: "olleH"

Q3. Write a Java program to check if a string contains a specific substring.
  - Input: "Hello World", Substring: "World"
  - Expected Output: True

Q4. Write a Java program to convert a string to lowercase.
  - Input: "HELLO"
  - Expected Output: "hello"

Q5. Write a Java program to convert a string to uppercase.
  - Input: "hello"
  - Expected Output: "HELLO"

Q6. Write a Java program to find the length of a string.
  - Input: "Hello"
  - Expected Output: 5

Q7. Write a Java program to concatenate two strings.
  - Input: "Hello", " World"
  - Expected Output: "Hello World"

Q8. Write a Java program to compare two strings for equality.
  - Input: "Hello", "hello"
  - Expected Output: False

Q9. Write a Java program to check if a string starts with a specific prefix.
  - Input: "Hello", Prefix: "He"
  - Expected Output: True

Q10. Write a Java program to check if a string ends with a specific suffix.
   - Input: "Hello", Suffix: "lo"
   - Expected Output: True

Q11. Write a Java program to replace a character in a string.
   - Input: "Hello", Old Char: 'o', New Char: 'a'
   - Expected Output: "Hella"

Q12. Write a Java program to remove a specific character from a string.
   - Input: "Hello", Char to remove: 'l'
   - Expected Output: "Helo"

Q13. Write a Java program to find the index of a character in a string.
   - Input: "Hello", Character: 'e'
   - Expected Output: 1

Q14. Write a Java program to find the last index of a character in a string.
   - Input: "Hello", Character: 'l'
   - Expected Output: 3

Q15. Write a Java program to check if a string is a palindrome.
   - Input: "madam"
   - Expected Output: True

Q16. Write a Java program to find a substring from a string.
   - Input: "Hello World", Start index: 0, End index: 5
   - Expected Output: "Hello"

Q17. Write a Java program to extract a part of a string (substring).
   - Input: "Hello World", Start index: 6
   - Expected Output: "World"

Q18. Write a Java program to split a string into an array of substrings.
   - Input: "Hello World", Delimiter: " "
   - Expected Output: ["Hello", "World"]

Q19. Write a Java program to check if a string is a number.
   - Input: "1234"
   - Expected Output: True

Q20. Write a Java program to count the occurrences of a character in a string.
   - Input: "Hello", Character: 'l'
   - Expected Output: 2

Q21. Write a Java program to find the first occurrence of a substring in a string.
   - Input: "Hello World", Substring: "World"
   - Expected Output: 6

Q22. Write a Java program to remove leading and trailing whitespaces from a string.
   - Input: "  Hello World  "
   - Expected Output: "Hello World"

Q23. Write a Java program to check if a string contains only digits.
   - Input: "12345"
   - Expected Output: True

Q24. Write a Java program to convert a string to a char array.
   - Input: "Hello"
   - Expected Output: ['H', 'e', 'l', 'l', 'o']

Q25. Write a Java program to convert a char array to a string.
   - Input: ['H', 'e', 'l', 'l', 'o']
   - Expected Output: "Hello"

Q26. Write a Java program to join two strings with a separator.
   - Input: "Hello", "World", Separator: "-"
   - Expected Output: "Hello-World"

Q27. Write a Java program to check if a string is a valid email address.
   - Input: "test@example.com"
   - Expected Output: True

Q28. Write a Java program to remove all vowels from a string.
   - Input: "Hello"
   - Expected Output: "Hll"

Q29. Write a Java program to find the longest word in a string.
   - Input: "I love programming in Java"
   - Expected Output: "programming"

Q30. Write a Java program to find the frequency of a word in a string.
   - Input: "Hello World Hello", Word: "Hello"
   - Expected Output: 2

Q31. Write a Java program to check if a string is an anagram of another string.
   - Input: "listen", "silent"
   - Expected Output: True

Q32. Write a Java program to replace a word in a string.
   - Input: "Hello World", Old Word: "World", New Word: "Java"
   - Expected Output: "Hello Java"

Q33. Write a Java program to convert the first letter of each word in a string to uppercase.
   - Input: "hello world"
   - Expected Output: "Hello World"

Q34. Write a Java program to check if a string is empty after trimming whitespace.
   - Input: "   "
   - Expected Output: True

Q35. Write a Java program to count the number of words in a string.
   - Input: "I love Java programming"
   - Expected Output: 4

Q36. Write a Java program to compare two strings lexicographically.
   - Input: "apple", "banana"
   - Expected Output: -1

Q37. Write a Java program to find the longest palindrome substring in a string.
   - Input: "babad"
   - Expected Output: "bab"

Q38. Write a Java program to check if a string contains only alphabetic characters.
   - Input: "HelloWorld"
   - Expected Output: True

Q39. Write a Java program to replace all spaces in a string with a specific character.
   - Input: "Hello World", Character to replace: '-'
   - Expected Output: "Hello-World"

Q40. Write a Java program to check if a string contains only lowercase letters.
   - Input: "hello"
   - Expected Output: True

Q41. Write a Java program to check if a string contains only uppercase letters.
   - Input: "HELLO"
   - Expected Output: True

Q42. Write a Java program to find the position of the first non-repeated character in a string.
   - Input: "swiss"
   - Expected Output: 0

Q43. Write a Java program to find the longest prefix of a string.
   - Input: "abcd", Prefix: "ab"
   - Expected Output: "ab"

Q44. Write a Java program to check if a string is a valid URL.
   - Input: "https://www.example.com"
   - Expected Output: True

Q45. Write a Java program to find the number of vowels in a string.
   - Input: "Hello World"
   - Expected Output: 3

Q46. Write a Java program to find the first non-repeated character in a string.
   - Input: "swiss"
   - Expected Output: "w"

Q47. Write a Java program to extract a substring from the beginning of a string.
   - Input: "Hello World", End index: 5
   - Expected Output: "Hello"

Q48. Write a Java program to check if a string is a valid phone number.
   - Input: "123-456-7890"
   - Expected Output: True

Q49. Write a Java program to repeat a string multiple times.
   - Input: "Hello", Times: 3
   - Expected Output: "HelloHelloHello"

Q50. Write a Java program to find the difference between two strings.
   - Input: "Hello", "Hella"
   - Expected Output: "o"

Q51. Write a Java program to split a string into an array of words.
   - Input: "I love programming"
   - Expected Output: ["I", "love", "programming"]

Q52. Write a Java program to join an array of strings into one string.
   - Input: ["I", "love", "Java"]
   - Expected Output: "I love Java"

Q53. Write a Java program to convert a string to a number (integer).
   - Input: "123"
   - Expected Output: 123

Q54. Write a Java program to convert a string to a float.
   - Input: "12.34"
   - Expected Output: 12.34

Q55. Write a Java program to convert an integer to a string.
   - Input: 123
   - Expected Output: "123"

Q56. Write a Java program to check if a string matches a given regular expression.
   - Input: "abc123", Regex: "[a-z]+[0-9]+"
   - Expected Output: True

Q57. Write a Java program to find the number of characters in a string excluding spaces.
   - Input: "Hello World"
   - Expected Output: 10

Q58. Write a Java program to split a string by commas.
   - Input: "apple,banana,cherry"
   - Expected Output: ["apple", "banana", "cherry"]

Q59. Write a Java program to remove a substring from a string.
   - Input: "Hello World", Substring: "World"
   - Expected Output: "Hello "

Q60. Write a Java program to capitalize the first letter of each word in a sentence.
   - Input: "hello world"
   - Expected Output: "Hello World"

Q61. Write a Java program to check if a string contains only whitespace characters.
   - Input: "    "
   - Expected Output: True

Q62. Write a Java program to find the common prefix between two strings.
   - Input: "flower", "flow"
   - Expected Output: "flow"

Q63. Write a Java program to find the last word in a string.
   - Input: "I love Java programming"
   - Expected Output: "programming"

Q64. Write a Java program to remove the first word in a string.
   - Input: "I love Java programming"
   - Expected Output: "love Java programming"

Q65. Write a Java program to find the longest word in a sentence.
   - Input: "I love programming in Java"
   - Expected Output: "programming"

Q66. Write a Java program to reverse each word in a string.
   - Input: "I love Java"
   - Expected Output: "I evol avaJ"

Q67. Write a Java program to remove all digits from a string.
   - Input: "Hello123"
   - Expected Output: "Hello"

Q68. Write a Java program to replace the first occurrence of a word in a string.
   - Input: "I love programming", Word to replace: "love", New word: "enjoy"
   - Expected Output: "I enjoy programming"

Q69. Write a Java program to check if a string is a valid integer.
   - Input: "1234"
   - Expected Output: True

Q70. Write a Java program to find the position of the last non-repeated character in a string.
   - Input: "swiss"
   - Expected Output: 0