Answer:
/*
* Method to print the letters in a passed in string by recursion. Each
* recursion compresses the string by excluding the last character one at a time
*/
public static void lettersOnly(String s) {
//If string is empty, return nothing
if (s.length() < 1) {
return;
}
// Get the last character of the string
char x = s.charAt(s.length() - 1);
// Check if the length of the string is 1 or less
// If it is 1 or less, check if the character is an alphabet
// A character x is an alphabet if its ASCII representation is
// between 65 and 90 (both inclusive) for uppercase letters
// or between 97 and 122 (both inclusive) for lowercase letters
// To get the ASCII representation, the character is type cast by prepending it
// with (int) e.g (int) z gives 122
if ((s == null) || (s.length() <= 1)) {
if ((((int) x >= 65 && (int) x <= 90)) || ((int) x >= 97 && (int) x <= 122))
System.out.println(s);
}
// else, if the length of the string is more than 1
else {
// Get the substring including all the characters in the string except the last
// character.
// Recall the function lettersOnly on the substring
lettersOnly(s.substring(0, s.length() - 1));
// Check if the last character of the string is an alphabet
// If it is, print it out.
if ((((int) x >= 65 && (int) x <= 90)) || ((int) x >= 97 && (int) x <= 122))
System.out.print(s.charAt(s.length() - 1));
}
} // End of method
Explanation:
Read through the comments of the code for better readability and understanding. To get a better representation of the code, the source file code has been attached to this response. Please download it and you can run it as a Java application on your machine.
Hope this helps!
