Why am I getting the above compile error when I am very clearly overriding abstract method compare (ditto abstract method compareTo)? Here is my code -- which was presented 1.5 code and I'm trying to retrofit to 1.4 -- followed by the complete compile time error. Thanks in advance for your help (even though I'm sure this is an easy question for you experts):
import java.util.*;
/**
This program sorts a set of item by comparing
their descriptions.
*/
public class TreeSetTest
{
public static void main(String[] args)
{
SortedSet parts = new TreeSet();
parts.add(new Item("Toaster", 1234));
parts.add(new Item("Widget", 4562));
parts.add(new Item("Modem", 9912));
System.out.println(parts);
SortedSet sortByDescription = new TreeSet(new
Comparator()
{
public int compare(Item a, Item b) // LINE CAUSING THE ERROR
{
String descrA = a.getDescription();
String descrB = b.getDescription();
return descrA.compareTo(descrB);
}
});
sortByDescription.addAll(parts);
System.out.println(sortByDescription);
}
}
/**
An item with a description and a part number.
*/
class Item implements Comparable
{
/**
Constructs an item.
@param aDescription the item's description
@param aPartNumber the item's part number
*/
public Item(String aDescription, int aPartNumber)
{
description = aDescription;
partNumber = aPartNumber;
}
/**
Gets the description of this item.
@return the description
*/
public String getDescription()
{
return description;
}
public String toString()
{
return "[descripion=" + description
+ ", partNumber=" + partNumber + "]";
}
public boolean equals(Object otherObject)
{
if (this == otherObject) return true;
if (otherObject == null) return false;
if (getClass() != otherObject.getClass()) return false;
Item other = (Item) otherObject;
return description.equals(other.description)
&& partNumber == other.partNumber;
}
public int hashCode()
{
return 13 * description.hashCode() + 17 * partNumber;
}
public int compareTo(Item other) // OTHER LINE CAUSING THE ERROR
{
return partNumber - other.partNumber;
}
private String description;
private int partNumber;
}
Compiler error:
TreeSetTest.java:25: <anonymous TreeSetTest$1> is not abstract and does not over
ride abstract method compare(java.lang.Object,java.lang.Object) in java.util.Com
parator
public int compare(Item a, Item b)
^
TreeSetTest.java:41: Item is not abstract and does not override abstract method
compareTo(java.lang.Object) in java.lang.Comparable
class Item implements Comparable
^
2 errors