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Java Java Objects (Retired) Delivering the MVP Validation

michaelabendroth
michaelabendroth
4,561 Points
Posted by michaelabendroth
michaelabendroth
4,561 Points

In the stage 4 delivering the MVP challenge, how do I check if the second letter in the field name is uppercase?

public class TeacherAssistant {

public static String validatedFieldName(String fieldName) { // These things should be verified: // 1. Member fields must start with an 'm' if (! fieldName.startsWith("m")) { throw new IllegalArgumentException("Member fields must start with 'm'.\n"); } // 2. The second letter in the field name must be uppercased to ensure camel-casing

char fieldArray [] = fieldName.toCharArray();
if (! Character.isUpperCase(fieldArray[2])) {
  throw new IllegalArgumentException("Fields must use camel-case.\n");
}
// NOTE:  To check if something is not equal use the != symbol. eg: 3 != 4
return fieldName;

}

}

TeacherAssistant.java 
public class TeacherAssistant {

  public static String validatedFieldName(String fieldName) {
    // These things should be verified:
    // 1.  Member fields must start with an 'm'
    if (! fieldName.startsWith("m")) {
      throw new IllegalArgumentException("Member fields must start with 'm'.\n");
    }
    // 2.  The second letter in the field name must be uppercased to ensure camel-casing

    char fieldArray [] = fieldName.toCharArray();
    if (! Character.isUpperCase(fieldArray[2])) {
      throw new IllegalArgumentException("Fields must use camel-case.\n");
    }
    // NOTE:  To check if something is not equal use the != symbol. eg: 3 != 4
    return fieldName;
  }

}

1 Answer

Ken Alger
STAFF
Ken Alger
Treehouse Teacher
Ken Alger
Ken Alger
Treehouse Teacher

Michael;

Remember that indexes in Java are 0 based, i.e. they start at zero (0). If we need to check the status of the second character in a string, that would reside at index position 1. A bit confusing at times, yes, but remember that we were age 0 for the first year of our lives too. :smile:

Post back if that clue didn't clear it up.

Happy coding,

Ken

michaelabendroth
michaelabendroth
4,561 Points
michaelabendroth
michaelabendroth
4,561 Points

Yep, I had that part ok - I noticed that the test case that failed was in the format of m_field_name so I changed from using array position 1 to array position 2 to get the 2nd letter.

Thanks for replying back - I'll keep trying to work out where I mucked this one up. :)

Ken Alger
Ken Alger
Treehouse Teacher
Ken Alger
Ken Alger
Treehouse Teacher

Michael;

I got the code your posted above to pass the challenge just fine by changing:

Character.isUpperCase(fieldArray[2]))

which indexes the third character in the Array to

Character.isUpperCase(fieldArray[1]))

which indexes the second character in the Array.

Hope it helps.

Ken

michaelabendroth
michaelabendroth
4,561 Points
michaelabendroth
michaelabendroth
4,561 Points

Thanks Ken! You are absolutely right - tried it again and it went right through. Appreciate it sir!