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Java Java Objects (Retired) Delivering the MVP Validation

Jordan Man
Jordan Man
2,736 Points

how do i validate whether the user has followed the member fields naming rules

if the member fields name doesnt meet requirements, how to throw and illegal argument exception. to validate the input.

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.indexOf("m", 1)){
      throw new IllegalArgumentException("This does not match the style we've talked about.");
    }



    return fieldName;
  }

}

1 Answer

Instead of indexOf(), try charAt() for the first test. For the second, use the Character.isLetter() and Character.isUpperCase() functions:

  public static String validatedFieldName(String fieldName) throws IllegalArgumentException {
    // 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' || 
        !Character.isLetter(fieldName.charAt(1)) || !Character.isUpperCase(fieldName.charAt(1))) {
      throw new IllegalArgumentException();
    } else {
      return fieldName;
    }
  }

Happy coding!

Jordan Man
Jordan Man
2,736 Points

Thank you very helpful :)