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Java Java Objects Creating the MVP Conference Registration Assistant

Can't solve

I wasn't able to solve the task. Could someone help me please? Fix the getLineNumberFor method to return a 1 if the first character of lastName is between A and M or else return 2 if it is between N and Z.

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

     */
    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

Ian Taylor
PLUS
Ian Taylor
Courses Plus Student 1,420 Points

Using those two top methods I get this error: onferenceRegistrationAssistant.java:11: error: bad operand types for binary operator '<=' ./ConferenceRegistrationAssistant.java:11: error: bad operand types for binary operator '<=' if(lastName <= 'M' && lastName >= 'A') { ^ first type: String second type: char ./ConferenceRegistrationAssistant.java:11: error: bad operand types for binary operator '>=' if(lastName <= 'M' && lastName >= 'A') { ^ If I use the compareTo() method it still doesn't work. I have even modified it with no luck.

lineNumber = lastName.charAt(0).compareTo('M); return lineNumber;

Ian Taylor
Ian Taylor
Courses Plus Student 1,420 Points

Ok I managed to get it working by

if (lastName.charAt(0) <= 'M'){ lineNumber = 1; }

Davis Hubbard
Davis Hubbard
19,896 Points

This problem can be solved using a simple if-else on a conditional similar to what is seen in the examples in Example.java. Something along the lines of

if(lastName <= 'M' && lastName >= 'A') { 
    lineNumber = 1; 
} 

with a complimentary else if to test N-Z should work well.

 public int getLineNumberFor(String lastName) {
    int lineNumber = 0;
    if(lastName <= 'M' && lastName >= 'A') {
      lineNumber = 1;
    } else {
      lineNumber = 2;
    }

I got 2 compiler errors now. ./ConferenceRegistrationAssistant.java:11: error: bad operand types for binary operator '<=' if (lastName <= 'M' && lastName >= 'A') { ^ first type: String second type: char ./ConferenceRegistrationAssistant.java:11: error: bad operand types for binary operator '>=' if (lastName <= 'M' && lastName >= 'A') { ^ first type: String second type: char Note: JavaTester.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 2 errors

Davis Hubbard
Davis Hubbard
19,896 Points

Try using the string method .CompareTo(). It takes a string to compare against as the argument, and returns an integer which tells how they compare. 0 is returned if they are equal, a negative value if the string is less than the argument, or a positive value if it is greater. Sorry for the confusion. Additional docs can be found here