Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Java Java Objects (Retired) Delivering the MVP Validation

Posted by Benyam Ephrem
Benyam Ephrem
3,185 Points

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?

TeacherAssistant.java 
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
STAFF
Ken Alger
Treehouse Teacher
Ken Alger
Ken Alger
Treehouse Teacher

Benyam;

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,

Ken