Java Regular Expression: Exercises, Practice, Solution

Java Regular Expression [30 exercises with solution]

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1. Write a Java program to check whether a string contains only a certain set of characters (in this case a-z, A-Z and 0-9).
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2. Write a Java program that matches a string that has a p followed by zero or more q's.
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3. Write a Java program to find sequences of lowercase letters joined by an underscore.
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4. Write a Java program to find the sequence of one upper case letter followed by lower case letters.
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5. Write a Java program that matches a string with a 'p' followed by anything ending in 'q'.
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6. Write a Java program to check if a word contains the character 'g' in a given string.
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7. Write a Java program that matches a word containing 'g', not at the start or end of the word.
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8. Write a Java program to match a string containing only upper and lowercase letters, numbers, and underscores.
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9. Write a Java program where a string starts with a specific number.
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10. Write a Java program to remove leading zeros from a given IP address.
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11. Write a Java program to check for a number at the end of a string.
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12. Write a Java program to replace Python with Java and code with coding in a given string.
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13. Write a Java program to find the word Python in a given string. If the word Python appears in the string return Java otherwise return C++. Ignore case sensitive.
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14. Write a Java program to count the number of vowels in a given string using a regular expression.
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15. Write a Java program to remove all vowels from a given string. Return the updated string.
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16. Write a Java program to replace all vowels in a string with a specified character.
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17. Write a Java program to count the number of decimal places in a given number.
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18. Write a Java program to validate a personal identification number (PIN). Assume a PIN number is 4, 6 or 8.
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19. Write a Java program to remove specific letters from a string and return the updated string.
Specific letters: "p", "q", or "r".
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20. Write a Java program that takes a number and sets a thousand separators for that number.
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21. Write a Java program to remove all non-alphanumeric characters from a given string.
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22. Write a Java program to validate a phone number.
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23. Write a Java program to move all lower case letters to the front of a given word. This will keep the relative position of all the letters (both upper and lower case) same.
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24. Write a Java program to separate consonants and vowels from a given string.
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25. Write a Java program to get the last n vowels of a given string.
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26. Write a Java program to check whether a given string is valid hex code or not.
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27. Write a Java program to add a dash before and after every vowel in a given string.
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28. Write a Java program to reverse words longer than 3 in a given string.
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29. Write a Java program to check if a given string is a mathematical expression or not.
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30. Write a Java program to insert a dash (-) between an upper case letter and a lower case letter in a string.
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