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Java Java Objects (Retired) Delivering the MVP Validation

2,973 Points

What's wrong with this code challenge?

Error reported: Bummer! "mFirstName" should have passed but invalid field name was reported.

I tested it with java-repl and it works.

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(0) == 'm' && Character.isUpperCase(fieldName.toCharArray()[1]))) {
      throw new IllegalArgumentException("Invalid field name");     

    return fieldName;


2 Answers

Harry James
Harry James
14,780 Points

Hey ms2030!

If you change the && in your if statement to a || then the challenge will pass :)

The reason being is that the code challenge will want to throw an exception if either the first character is a capital or if the second character isn't a capital - not just when both are done wrong.

Hope it helps!

2,973 Points


private char validateGuess(char letter) {
    if (!Character.isLetter(letter)) {
      throw new IllegalArgumentException("A letter is required."
    letter = Character.toLowerCase(letter);
    if (mMisses.indexOf(letter) >= 0 || mHits.indexOf(letter) >= 0) { 
      throw new IllegalArgumentException(letter + " has already been guessed")           }
    return letter;
  • The above code is the example to follow.
  • We care about charAt for this challenge, rather than indexOf
  • In pseudocode, we want to check for the following condition, and throw an error: " if the character at index 0 of fieldName does not equal 'm' OR the character at index 1 of fieldName is not upper case"