What's wrong with the line with a comment?

Question

Help.
```TeacherAssistant.java
public class TeacherAssistant {
  public static String validatedFieldName(String fieldName) {
    String mFieldName = fieldName;
    if (mFieldName.charAt(0) != 'm') {  //Whats's wrong with this line?
      throw new IllegalArgumentException("Wrong first letter");
    }
    if (Character.toUpperCase(mFieldName.charAt(1)) != mFieldName.charAt(1)) {
      throw new IllegalArgumentException("Wrong second letter");
    }
    // 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
    return fieldName;
  }
}
```

Romel Liwag · Accepted Answer

Try this code and happy Coding :)
```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
    Boolean memberField = fieldName.charAt(0) =='m';
    if(!memberField || !Character.isLetter(fieldName.charAt(1)) ||
       fieldName.charAt(1) != Character.toUpperCase(fieldName.charAt(1)) ){
     throw new IllegalArgumentException ("Start with 'm' and use camel-casing");
    }  
    return fieldName;
  }
}
```

Jess Sanders · Answer

The commented line is perfectly fine.  It's your second condition that needs fixing.  Try this,
java
if (!Character.isUpperCase(mFieldName.charAt(1))){
      throw new IllegalArgumentException("Wrong second letter");
    }

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Roman Zhyvitski

Roman Zhyvitski

What's wrong with the line with a comment?

2 Answers

Romel Liwag

Romel Liwag

Jess Sanders

Jess Sanders