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Java Java Objects (Retired) Delivering the MVP Validation

Posted by Lachlan Kruger
Lachlan Kruger
Courses Plus Student 1,868 Points

Need Help

I Don't Know Why It Isn't Working

TeacherAssistant.java 
public class TeacherAssistant {

  public static String validatedFieldName(String fieldName) {
    char name = fieldName.charAt(1);
    // 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
    while(!fieldName.contains("m") && !fieldName.isTitleCase(1)){
       throw new IllegalArgumentException("Name Needs To Start With The Letter M");
    }


    return fieldName;
  }

}

2 Answers

Jordan Payne
Jordan Payne
5,478 Points
Jordan Payne
Jordan Payne
5,478 Points
  • Think about using an "if" statement instead of a while loop.
  • Use the "if" statement to check whether to throw the exception
  • If the character at position 0 != m, throw the exception OR if the character at position 1 is not upper case, throw the exception
  • Have a look at Character.isUpperCase(char c) for the second condition.
Lachlan Kruger
Lachlan Kruger
Courses Plus Student 1,868 Points

I Changed It But I'm Not Sure Why It Wont Work? My Code:

public class TeacherAssistant {

public static String validatedFieldName(String fieldName) { if(!fieldName.contains("m") && !Character.isUpperCase(1)){

     throw new IllegalArgumentException("Name Needs To Start With The Letter M");

}
return fieldName;

}

}

Jordan Payne
Jordan Payne
5,478 Points
Jordan Payne
Jordan Payne
5,478 Points
  • You're very close, read my third bullet point above. Note the OR instead of the AND.
  • The argument for Character.isUpperCase() is a character, not an integer. You want to feed the character at index 1 in your fieldName String to that method. Try using the .chartAt(int index) method to get the character you want.
  • fieldName.contains("m") will return true if "m" is anywhere inside the String assigned to fieldName. You could do away completely with the .contains() method and instead use .charAt(int index) to check if the character at index 0 != 'm'.