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Java Java Objects (Retired) Delivering the MVP Validation

How do I check if a letter is upper or lower case?

Theoretically wouldn't my code complete the challenge? I assume there must be a method for this I am over looking. In my second IF statement, what method can check if a string's certain letter is upper case or lower case?

public class TeacherAssistant {

  public static String validatedFieldName(String fieldName) {
    // These things should be verified:
    // 1.  Member fields must start with an 'm'
    // 2.  The second letter in the field name must be uppercased to ensure camel-casing
    // NOTE:  To check if something is not equal use the != symbol. eg: 3 != 4
    if (fieldName.charAt(0) != 'm')
      throw new IllegalArgumentException("Field name must start with a letter m.");
    if (fieldName.charAt(1) != 'A'|'B'|'C'|'D'|'E'|'F'|'G'|'H'|'I'|'J'|'K'|'L'|'M'|'N'|'O'|'P'|'Q'|'R'|'S'|'T'|'U'|'V'|'W'|'X'|'Y'|'Z')     
      throw new IllegalArgumentException("Second character must be an uppercase letter.");
    return fieldName;


2 Answers

Ken Alger
Ken Alger
Treehouse Teacher


There are methods for checking if a char is upper or lower case, isUpperCase() and isLowerCase() respectively. They both accept a char as an argument and return a boolean true or false. You can read about them further in the Java documentation on the Character Class.

Happy coding,