validation

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    
    char first =  fieldName.charAt(0);
    char second = fieldName.charAt(1);
    if(first != 'm'){
      throw new IllegalArgumentException( "field name should start with m.");
    }
    if(!Character.isUpperCase(second )){
      throw new IllegalArgumentException( "second letter should be uppercase");
    }
    return fieldName;
  }
}