Need some help with charAt...

Question

What the challenge is asking me to do is to return a 1 if the last name is between 'A' thru 'M', and return a 2 if it is between 'N' thru 'Z'. My code isn't compiling, I tried other ways of doing this but it keeps giving me syntax errors. I am a little stuck with this and don't want to waste more time then I already have. "you learn by asking"...

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 = 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('a' <= 'm')) {
      lineNumber = 1;
    }

    if (lastName.charAt('n' <= 'z')) {
      lineNumber = 2;
    }

    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");
  }

}

Answer 1 · 2017-07-21T08:50:07Z

July 21, 2017 8:50am

Hi Gabriel,

you need to compare only the first letter in the String. charAt is expecting an index, but you are giving it a comparison. You need the comparison between the first char AND 'M' Try it that way.

// first letter in a String is Index 0
if (lastName.charAt(0) <= 'M') {
    lineNumber = 1;
} else {
// a simple if else statement should work in this case
   lineNumber = 2;
}

I hope that helped.

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Gabriel Favela

Gabriel Favela

Need some help with charAt...

1 Answer

Felix Sonnenholzer

Felix Sonnenholzer