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

Jordan Man
Jordan Man
2,736 Points
Posted by Jordan Man
Jordan Man
2,736 Points

how do i validate whether the user has followed the member fields naming rules

if the member fields name doesnt meet requirements, how to throw and illegal argument exception. to validate the input.

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.indexOf("m", 1)){
      throw new IllegalArgumentException("This does not match the style we've talked about.");
    }



    return fieldName;
  }

}

1 Answer

jcorum
jcorum
71,830 Points
jcorum
jcorum
71,830 Points

Instead of indexOf(), try charAt() for the first test. For the second, use the Character.isLetter() and Character.isUpperCase() functions:

  public static String validatedFieldName(String fieldName) throws IllegalArgumentException {
    // 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' || 
        !Character.isLetter(fieldName.charAt(1)) || !Character.isUpperCase(fieldName.charAt(1))) {
      throw new IllegalArgumentException();
    } else {
      return fieldName;
    }
  }

Happy coding!

Jordan Man
Jordan Man
2,736 Points
Jordan Man
Jordan Man
2,736 Points

Thank you very helpful :)