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Java Java Objects Creating the MVP Conference Registration Assistant

Why wont this compile? It is telling me I cannot use the comparison operators

I just don't see anything wrong

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) {
    if (lastName.charAt(0) < "N") {
    int lineNumber = 1;
    }else{
    int 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");
  }

}

2 Answers

Todd Anderson
Todd Anderson
4,260 Points

At first glance it looks like you are using double quotes to compare a char in your getLineNumberFor method which should be single quotes in Java. The other thing is that you do not need to create an int. It just wants you to either return 1 or 2... so if... return 1; else return 2;

Good luck.

Thanks I had such a hard time catching the double quotes that I will likely never miss this particular error again!

I re-wrote your function a little bit:

public class ConferenceRegistrationAssistant {


  public int getLineNumberFor(String lastName) {

    int lineNumber = 0;
    // get the  first char from the last name
    char charLetter = lastName.charAt(0);
    // make it a string type
    String firstLetter = Character.toString( charLetter );

    // create the result variable
    // this value will be less than 0 if firstlLetter is lower than "N"
    // this value will be greater than 0 if firstlLetter is higher than "N"
    // it will return 0 if both strings are equal
    int result = firstLetter.compareTo( "N" );

    if ( result < 0 ) {

      lineNumber = 1;

    }
    else{

      lineNumber = 2;

    }

   return lineNumber;
  }

}

I hope this helps, cheers.

Todd Anderson
Todd Anderson
4,260 Points

Why not...

public int getLineNumberFor(String lastName) { if (lastName.charAt(0) < 'N') { return 1; }else{ return 2; } }

Much cleaner and simpler.