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Java Java Objects Creating the MVP Conference Registration Assistant

I have absolutely no clue how to start this :( sorry for the lack of attempt but my mind is blank.

any help appreciated

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) {
    int lineNumber;
    lineNumber = lastName.charAt(0);

    /*
      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");
  }

}

1 Answer

Felix Sonnenholzer
Felix Sonnenholzer
14,654 Points

Hi there,

don't worry, having a blank mind happens to everyone.

In the Example.java you have a few examples for char comparison. So, since only the first letter of the last name is relevant we would extract that one and take a look at it.

    public int getLineNumberFor(String lastName) {
      int lineNumber = 0;
    /*
      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

     */
      if (lastName.charAt(0) <= 'M') {
        lineNumber = 1;
      } else {
        lineNumber = 2;
      }
      return lineNumber;
    }

Because it is a single char you can make simple comparsions with <, >, and so on. Think of it in this case like the position in the alphabet. A is 1 B is 2 ... E is 5 and so on.

Since A - M (thought as numbers) are smaller than or equal M this comparison works just fine for chars.

If there is still something not clear, just ask

Thanks a lot Felix I understand now :)