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Java Java Objects (Retired) Delivering the MVP Validation

Posted by Sohaib Rashid
Sohaib Rashid
627 Points

I don't know what is wrong here, i get an error mesasage of bad operand type String for unary operator '!'

I know what the error is, i don't know to fix it

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) {
      throw new IllegalArgumentException();
    }

    return fieldName;
  }

}
Dovev Golan
Dovev Golan
425 Points

Hey,

The "!" operator is for boolean variants.

Try this :

If (fieldName == null) .....

1 Answer

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

Hello, I think I answered your other question, but just incase. Try the following code 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;
  }
}

You are first checking to make sure that the char 'm' is the first char in the string, then you are checking to make sure that the second is capitalized. If either of these conditions are not met than you are throwing the exception.

Thanks, let me know if this helps!

Sohaib Rashid
Sohaib Rashid
627 Points

ahh you made it so much easier to understand! you have definitely helped! thank you and happy coding!