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Java Java Objects (Retired) Delivering the MVP Validation

Posted by Pixel HD
.a{fill-rule:evenodd;}techdegree
Pixel HD
Android Development Techdegree Student 968 Points

Can't pass

Keeps saying "mFirstName" should pass but failed.

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') != 0) {
      throw new IllegalArgumentException("m must be at index 0");
    }
    if (Character.isLetter(fieldName.indexOf(1)) && Character.isLowerCase(fieldName.indexOf(1)) || !Character.isLetter(fieldName.indexOf(1))) {
      throw new IllegalArgumentException("must be camel case");
    }
    return fieldName;
  }

}

1 Answer

Jennifer Nordell
seal-mask
STAFF
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

Pixel HD Hi there! You're doing great, but it seems like you've mixed up indexOf and charAt a bit. If I modify your code just a teensy bit and rework the check for the lower case m then change out the indexOf to charAt, it passes! Take a look at your modified code:

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("m must be at index 0");
    }
    if (Character.isLetter(fieldName.charAt(1)) && Character.isLowerCase(fieldName.charAt(1)) || !Character.isLetter(fieldName.charAt(1))) {
      throw new IllegalArgumentException("must be camel case");
    }
    return fieldName;
  }
}

indexOf searches a string and then reports back the index where it found that character or substring. charAt looks at a specific index. Hope this is helpful! :smiley:

Thomas Nilsen
Thomas Nilsen
14,957 Points
Thomas Nilsen
Thomas Nilsen
14,957 Points

I was just about to answer as well :)

I do think the last if could be written more easily:

if (!Character.isUpperCase(fieldName.charAt(1))) {
            throw new IllegalArgumentException("must be camel case");
        }

**Edit

I read your code way to quickly - you just had an extra check, which is good! :)

Jennifer Nordell
seal-mask
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
.a{fill-rule:evenodd;}techdegree
Jennifer Nordell
Treehouse Teacher

I agree with you, though Thomas Nilsen. For my own personal solution I combined the check. And there is at least one time that Treehouse send in a string like m_something_something. Which means that the challenge will fail if it doesn't check to make sure the character at the index of 1 is a letter. Here was my check/throw statement:

    if (fieldName.charAt(0) != 'm' || !Character.isLetter(fieldName.charAt(1)) || Character.isLowerCase(fieldName.charAt(1)))    {
      throw new IllegalArgumentException("Invalid format");
    }

But in reality, I sort of like that he has the Exceptions divided up to let the user know what they're doing incorrectly :thumbsup: