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Java Java Objects (Retired) Delivering the MVP Validation

Posted by Hank Tran
Hank Tran
652 Points

Help me.

validation

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.charAt(0) != 'm') {
      throw new IllegalArgumentException("Make sure field name begins with n");
    }
    if(2.  The second letter in the field name must be uppercased to ensure camel-casing) {
      throw new IllegalArgumentException("The second letter in the field name must be uppercased.");
    }
    return fieldName;
  }

}

2 Answers

Grigorij Schleifer
Grigorij Schleifer
10,365 Points
Grigorij Schleifer
Grigorij Schleifer
10,365 Points

Hi Hank,

you should delete this line of code:

2.  The second letter in the field name must be uppercased to ensure camel-casing inside of the second if-statement.

It is better to use a Character class for your if-statement, because this class provides methods to proof whether a char in a String is upper- or lowercased. The String class does not, so you can´t write

if (! fieldname.isUpperCase(charAt(1)){
      throw new IllegalArgumentException("The second letter in the field name must be uppercased.");
}

bacause String "fieldName" doesnt contain the method like isUpperCase() this code would fail The Character class contains the method...

Look here :

http://docs.oracle.com/javase/7/docs/api/java/lang/Character.html

So you should use a statement like this:

    if(! Character.isUpperCase(fieldName.charAt(1))){
     throw new IllegalArgumentException("the second letter in the field name must be uppercased");
    }
    return fieldName;
  }

The Character contains a method to proof whether a String at char 1 (second char in the fieldName String) is uppercased or not. If the result is true (it is not - the compiler throws the exception, if false (second char is uppercased) the method returns the fieldName.

I hope I could explain it well, because english is not my best language :)

Best wishes and stay passionate for java ...

Seth Kroger
Seth Kroger
56,413 Points
Seth Kroger
Seth Kroger
56,413 Points

It looks like you copy-pasted the comment into the 2nd if statement, which is not a valid conditional statement. If you replace it with a conditional to check if the 2nd letter is uppercase, it should work fine.