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Java Java Objects Creating the MVP Conference Registration Assistant

Binyamin Friedman
Binyamin Friedman
14,615 Points

Wierd error around getChar()

./ConferenceRegistrationAssistant.java:13: error: cannot find symbol if(A_M.contains(lastName.getChar(0))) { ^ symbol: method getChar(int) location: variable lastName of type String Note: JavaTester.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 1 error

ConferenceRegistrationAssistant.java
public class ConferenceRegistrationAssistant {

  /**
   * Assists in guiding people to the proper line based on their last name.
   *
   * @param lastName The person's last name
   * @return The line number based on the first letter of lastName
   */
  public int getLineNumberFor(String lastName) {
    final String A_M = "ABCDEFGHIJKLM";
    int lineNumber = 0;

    if(A_M.contains(lastName.getChar(0))) {
      lineNumber = 1;
    } else {
      lineNumber = 2;
    }
    /*
      lineNumber should be set based on the first character of the person's last name
      Line 1 - A thru M
      Line 2 - N thru Z

     */
    return lineNumber;
  }

}
Example.java
public class Example {

  public static void main(String[] args) {
    /*
      IMPORTANT:  You can compare characters using <, >. <=, >= and == just like numbers
     */
    if ('C' < 'D') {
      System.out.println("C comes before D");
    }

    if ('B' > 'A') {
      System.out.println("B comes after A");
    }

    if ('E' >= 'E') {
      System.out.println("E is equal to or comes after E");
    }

    // This code is here for demonstration purposes only...
    ConferenceRegistrationAssistant assistant = new ConferenceRegistrationAssistant();
    /*
      Remember that there are 2 lines.
      Line #1 is for A-M
      Line #2 is for N-Z
     */
    int lineNumber = 0;
    /*
      This should set lineNumber to 2 because
      The last name is Zimmerman which starts with a Z.
      Therefore it is between N-Z
     */
    lineNumber = assistant.getLineNumberFor("Zimmerman");

    /*
      This method call should set lineNumber to 1, because 'A' from "Anderson" is between A-M.
     */
    lineNumber = assistant.getLineNumberFor("Anderson");

    /*
      Likewise Charlie Brown's 'B' is between 'A' and 'M', so lineNumber should be set to 1
     */
    lineNumber = assistant.getLineNumberFor("Brown");
  }

}

3 Answers

Leandro Botella Penalva
Leandro Botella Penalva
17,618 Points

lastName is a String and a String doesn't have a method called "getChar". To pick up a character at a certain position of a string you should use instead the "charAt" method. In your case to pick up the first character would be: lastName.charAt(0). However this won't work either as the "charAt" method returns a char type value and the "contains" method you used in the A_M String variable doesn't allow you to pass char type values.

To solve this challenge I suggest you to take a closer look at the Example.java file and how it shows you to compare characters.

Binyamin Friedman
Binyamin Friedman
14,615 Points

Thank you. I didn't realize you could compare letters with > < signs.

Binyamin Friedman
Binyamin Friedman
14,615 Points

I changed my code and used this: if(lastName.charAt(0) <= 'm' && lastName.charAt(0) >= 'a') { lineNumber = 1; } else { lineNumber = 2; }

But, the quiz says that it entered Mandela and it returned 2 instead of 1.

Leandro Botella Penalva
Leandro Botella Penalva
17,618 Points

Java takes characters as numbers, so internally is comparing numbers. Each character represents a number. Here is a few character codes: http://www.ascii-code.com/ DEC column is the numeric value that represents and the Symbol column is the actual character.

So, said that you are comparing lower case characters but the name's first letter is upper case.

In the ASCII Table:

'a' = 97

'm' = 109

'M' = 77

So with the name Mandela the 'M' is lower than 'm' but not greater than 'a'.