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Java Java Objects (Retired) Delivering the MVP Validation

Grigorij Schleifer
Grigorij Schleifer
10,365 Points

Analysing String firstName with charAt() method

public class TeacherAssistant {

  public static String validatedFieldName(String fieldName) {

      throw new IllegalArgumentException("second char is not uppercase ");
    if(fieldName.charAt(0) != m){
      throw new IllegalArgumentException("first char is not right");
    return fieldName;


This code works fine. But i donΒ΄t understand why we use a method from a Character wrapper class to analyse a String ???

2 Answers

The reason we use the Character wrapper class is not to analyze the string, but to analyze the characters in the String. There are no methods available, other than in the Character class, that will let us determine whether or not a specific letter in a String is uppercase or lowercase. For us to be able to do this, we must utilize another class to help, which is the Character class.

I hope this clears things up. Happy coding!

Iain Diamond
Iain Diamond
29,379 Points

Hi Grigorij,

The charAt() method takes a String type and returns a Character type, so using Character class methods to test the return type would seem best.

Hope this helps. iain


should the second test be?

    if(fieldName.charAt(0) != 'm'){