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Java Java Objects (Retired) Delivering the MVP Validation

Jonathan Weinstein
Jonathan Weinstein
9,063 Points

How to combine "indexOf" and "isUpperCase"?

See the conditional if statement. How should I combine these?

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' && fieldName.indexOf(1).isUpperCase()) {
      return fieldName;
    } else {
      throw new IllegalArgumentException ("The value is not okay.");


2 Answers

Ken Alger
Ken Alger
Treehouse Teacher


There is a good discussion on this topic here.


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"