Java Program: String input validation for vowels

Java Exception Handling: Exercise-7 with Solution

Write a Java program to create a method that takes a string as input and throws an exception if the string does not contain vowels.

Sample Solution:

Java Code:

public class Vowel_Check {
  public static void main(String[] args) {
    try {
      String text = "Java handling and managing exceptions ";
      // String text = "Typy gyps fly.";
      System.out.println("Original string: " + text);
      checkVowels(text);
      System.out.println("String contains vowels.");
    } catch (NoVowelsException e) {
      System.out.println("Error: " + e.getMessage());
    }
  }

  public static void checkVowels(String text) throws NoVowelsException {
    boolean containsVowels = false;
    String vowels = "aeiouAEIOU";

    for (int i = 0; i < text.length(); i++) {
      char ch = text.charAt(i);
      if (vowels.contains(String.valueOf(ch))) {
        containsVowels = true;
        break;
      }
    }
    if (!containsVowels) {
      throw new NoVowelsException("String does not contain any vowels.");
    }
  }
}
class NoVowelsException extends Exception {
  public NoVowelsException(String message) {
    super(message);
  }
}

Sample Output:

Original string: Java handling and managing exceptions
String contains vowels.

Original string: Typy gyps fly.
Error: String does not contain any vowels

Explanation:

In the above exercise,

• The main method is defined in the Vowel_Check class and serves as the program entry point.
• In the main method, a string of text is initialized with a value. This string represents the input to be checked for vowels.
• The checkVowels method is called, passing the text string as an argument. This method checks if the string contains vowels.
• Inside the checkVowels method, a boolean variable containsVowels is initialized as false. This variable tracks whether vowels are found in the string.
• A for loop iterates through each character of the text string.
• After the loop, if containsVowels is still false, it means no vowels were found in the string. In this case, a NoVowelsException is thrown with the message "String does not contain any vowels."
• The NoVowelsException class is a custom exception class that extends the base Exception class. It provides a constructor that takes a message parameter and passes it to the superclass constructor using the super keyword.
• If a NoVowelsException occurs in the main method, it is caught, and an appropriate error message is printed.

Flowchart:

Java Code Editor:

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