How can you test if a character is between 'a' and 'z'?

Question:

How can you validate that a scanner input is a character between 'a' and 'z'?

Code:

import java.util.Scanner;
public class ReadChar {
 
  public static void main(String[] args) {
 
    Scanner sc = new Scanner( System.in );
 
    String str = "";
    while(true) {
      System.out.print("Please enter a letter: ");
      str = sc.nextLine();
      if(str.length() == 1) {
        char c = str.charAt(0);
        if( (c >= 'a') && (c <= 'z')) {
          break;
        }
      }
      System.out.println("Try again.");
    }
    System.out.println("You entered: " + str);
 
  }
}

Output:

$ java ReadChar
Please enter a letter: A
Try again.
Please enter a letter: s
You entered: s