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Java Java Objects Creating the MVP Conference Registration Assistant

Carlo Antonio Bilbao
Carlo Antonio Bilbao
24,113 Points

How did you solve the first letter exercise?

How did you solve the first letter exercise? Here is my code, but I'm getting an error...

public int getLineNumberFor(String lastName) { int lineNumber = 0; char firstLetter = lastName.charAt(0); if (firstLetter == 'a' || 'b' || 'c' || 'd' || 'e' || 'f' || 'g' || 'h' || 'i' || 'j' || 'k' || 'l' || 'm') { 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;

}

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;
    char firstLetter = lastName.charAt(0);
    if (firstLetter == 'a' || 'b' || 'c' || 'd' || 'e' || 'f' || 'g' || 'h' || 'i' || 'j' || 'k' || 'l' || 'm') {
      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");
  }

}

1 Answer

andren
andren
28,558 Points

I think you should look at some of the code in the example.java file found in the challenge workspace, this bit in particular:

/*
      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");
    }

Using character comparison as shown above this challenge can be solved with an if statement with as little as one condition.

Anyway the reason why your code results in a compilation error is that when you use || or && to specify multiple condition each condition has to be a valid condition that would work if it was used by itself on its own. In other words you have to compare firstLetter to the given letter in all the conditions, you can't just give a list of letters like you have done.

Here is an example of how the code would have to look if you wanted to go the route you are trying to do:

if (firstLetter == 'a' || firstLetter == 'b' || firstLetter == 'c' || firstLetter == 'd' || firstLetter == 'e' ||  firstLetter =='f' || firstLetter == 'g' || firstLetter == 'h' || firstLetter == 'i' || firstLetter == 'j' || firstLetter == 'k' || firstLetter == 'l' || firstLetter == 'm') {
      lineNumber = 1;
    } else {
      lineNumber = 2;
    }