Simple api which takes letter as an input from the console and shows in the output whether it is a vowel or consonant, and it continues until 'exit' keyword is entered.

• Project is built on gradle building tool, to run the program, enter to the directory where main class is located, the rung the following command './gradlew build'. When building is successful, find executable file *.jar. Then run the following command 'java -jar lib.jar'

• The program starts by importing the Scanner class from the java.util package, which allows reading user input.
• In the main method, a Scanner object named input is created to read user input.
• The program then enters an infinite loop (while (true)) to continuously prompt for user input.
• Within the loop, it displays a message to enter "exit" at any time to stop the program. It also prompts the user to enter a letter.
• The entered letter is stored in the letter variable.
• If the entered letter is equal to exit, the program calls System.exit(1) to terminate.
• If the length of the entered letter is not equal to 1, it means the user entered more than one character. In that case, it displays a message asking the user to enter only one letter.
• If the entered letter is a single character, it checks if it is one of the vowels ("a," "e," "i," "u," "o," or "y"). If it matches any of the vowels, it displays a message indicating that the letter is a vowel. Otherwise, it displays a message indicating that the letter is a consonant.
• After each iteration, it prints a line of dashes to separate the outputs.
• The program will continue prompting for input until the user enters "exit" to terminate the program.