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Java Java Objects (Retired) Delivering the MVP Validation

Sohaib Rashid
Sohaib Rashid
627 Points
Posted by Sohaib Rashid
Sohaib Rashid
627 Points

If someone can walk me through this, i would highly appreciate it! I know i have to use an if loop but I've tried

ive tried a lot of different ways but there always seems to be an error! Happy Coding! the task is : So I was wondering if you could help me with some of these code challenges. As you might've seen when a member field name doesn't match the style we've talked about, I send an error about it. Let's write some code to validate the style of the field name.

I've added the method validatedFieldName it will return the validated field name. If the value passed in doesn't meet the requirements, throw an IllegalArgumentException. I'll keep you posted on the results every time you press check work.

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
    return fieldName;
  }

}

3 Answers

Rob Bridges
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.a{fill-rule:evenodd;}techdegree seal-36
Rob Bridges
Full Stack JavaScript Techdegree Graduate 35,467 Points
Rob Bridges
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Rob Bridges
Full Stack JavaScript Techdegree Graduate 35,467 Points

Hello!

So the first thing we want to do is make sure that the first character in the field name is the character 'm'

We can do this by the following

if (fieldName.charAt(0) != 'm')

The second part is we want to make sure that the second letter is captial, we can do this by.

if (!Character.isUpperCase(fieldName.charAt(1))

To combine it all together it would look something like below.

public class TeacherAssistant {

  public static String validatedFieldName(String fieldName) {
    // These things should be verified:
    if (fieldName.charAt(0) != 'm' || !Character.isUpperCase(fieldName.charAt(1)) ) {
      throw new IllegalArgumentException("Illegal field name");
    }
    // 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
    return fieldName;
  }
}
Sohaib Rashid
Sohaib Rashid
627 Points
Sohaib Rashid
Sohaib Rashid
627 Points

Thanks man! You have a great way of explaining! A lot of help, thanks and happy coding!

Jess Sanders
Jess Sanders
12,086 Points
Jess Sanders
Jess Sanders
12,086 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"
Unsubscribed User
Unsubscribed User
3,091 Points
Unsubscribed User
Unsubscribed User
3,091 Points

That mostly makes sense, what I am not getting is where does Character come from? What is Character

from Character.toLowerCase(letter) or !Character.isLetter

Rob Bridges
seal-mask
.a{fill-rule:evenodd;}techdegree seal-36
Rob Bridges
Full Stack JavaScript Techdegree Graduate 35,467 Points
Rob Bridges
.a{fill-rule:evenodd;}techdegree seal-36
Rob Bridges
Full Stack JavaScript Techdegree Graduate 35,467 Points

Hey Brendon.

Character is a defined class already in Javascript, so that's why you're not seeing it defined anywhere, it's actually a wrapper class that you can call methods on if you pass it in the valuable of char like in this instance where we 

Character.isUpperCase(fieldName.charAt(1));

We're actually just calling the Character class, and passing it in a char as a value, in this instance to check and see if the certain character is upperCase.

Thanks.