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Java Java Objects (Retired) Delivering the MVP Validation

Daniel Schwemmlein
Daniel Schwemmlein
4,960 Points
Posted by Daniel Schwemmlein
Daniel Schwemmlein
4,960 Points

How do I make sure my second letter is uppercase?

Hi there. Another question about the same java script challenge. I was supposed to write a code that recognizes a lowercase letter and throws an illegalArgumentException otherwise The second letter in the field name must be uppercased to ensure camel-casing. How do I make sure that my code checks if the second letter is uppercased? With another charAt(1) ? please help me out here

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("Error, needs to start with letter 'm'.");
    }

    return fieldName;
  }

}

2 Answers

Parker Busswood
Parker Busswood
20,207 Points
Parker Busswood
Parker Busswood
20,207 Points

Hey Daniel,

You've got the first part right from what I can see, you're correctly checking if the first letter is 'm'. Now, as you suggest, you can use charAt(1) to find the character at index 1, which is the 2nd letter. The Character class has an isUpperCase method that you can use, and it returns a boolean:

if (!Character.isUpperCase(fieldName.charAt(1))){
    throw new IllegalArgumentException("Error, variable name must be in camel case.");
}

So above, I'm checking if the 2nd character is upper case, and using the '!' character to flip this and check if it's not upper case.

Hope this helps!

Parker