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Java Java Objects (Retired) Delivering the MVP Validation

Posted by Thomas Katalenas
Thomas Katalenas
11,033 Points

I've added the method validatedFieldName it will return the validated field name. If the value passed in doesn't meet th

Here are the errors!!

./TeacherAssistant.java:8: error: char cannot be dereferenced
    if(fieldName.charAt(0) == 'm' && fieldName.charAt(1) == fieldName.charAt(1).toUpperCase()){
                                                                               ^
./TeacherAssistant.java:10: error: cannot find symbol
    }else{throw IllegalArgumentException("first letter doesn't start with m or second letter not Uppercased");
                ^
  symbol:   method IllegalArgumentException(String)
  location: class TeacherAssistant
2 errors
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' && fieldName.charAt(1) == fieldName.charAt(1).toUpperCase()){
      return fieldName;
    }else{throw IllegalArgumentException("first letter doesn't start with m or second letter not Uppercased");
    }
  }

}

3 Answers

Jeremy Hill
Jeremy Hill
29,567 Points
Jeremy Hill
Jeremy Hill
29,567 Points

I would do it this way:

public class TeacherAssistant {

  public static String validatedFieldName(String fieldName) {
        if(fieldName.charAt(0) != 'm' || Character.isUpperCase(fieldName.charAt(1)) == false)
            throw new IllegalArgumentException("Not a valid Field Name!");
        else
            return fieldName;
  }

}
Jeremy Hill
Jeremy Hill
29,567 Points

You should be using the '||' (or) character instead of the && (and) because when you use "and" you are saying that both conditions have to be met in order to throw the exception; in this case it just needs to be one or the other.

Thomas Katalenas
Thomas Katalenas
11,033 Points
Thomas Katalenas
Thomas Katalenas
11,033 Points

where are you getting Character from ?

Jeremy Hill
Jeremy Hill
29,567 Points
Jeremy Hill
Jeremy Hill
29,567 Points

If you are familiar with java.lang.Object, it is a class that ALL objects inherit from; well the Character class is a child class of java.lang.Object as well. To put it in easier terms, all Objects have access to the class Character and all of its methods. so the method isUpperCase() as well as isLowerCase() both are in the Character class. In order to use the methods just type Character. and then the method that you are wanting to use. If you want to know more about it go this website and try using some of the methods from it- you will find them really helpful once you know about them.

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