import java.util.*; 
public class TreeSetTest { 
  /** 
   * @param args 
   */ 
  public static void main(String[] args) { 
    // TODO Auto-generated method stub 
    SortedSet<Item> parts=new TreeSet<Item>(); 
    parts.add(new Item("Toaster", 1234)); 
    parts.add(new Item("Widget", 4562)); 
    parts.add(new Item("Modem", 9912)); 
    System.out.println(parts); 
    SortedSet<Item> sortByDescription=new TreeSet<Item>(new  
        Comparator<Item>() 
        { 
          public int compare(Item a, Item b) 
          { 
            String descrA=a.getDescription(); 
            String descrB=b.getDescription(); 
            return descrA.compareTo(descrB); 
          } 
        }); 
    sortByDescription.addAll(parts); 
    System.out.println(sortByDescription); 
  } 
} 
class Item implements Comparable<Item> 
{ 
  public Item(String aDescription, int aPartNumber) 
  { 
    description=aDescription; 
    partNumber=aPartNumber; 
  } 
  public String getDescription() 
  { 
    return description; 
  } 
  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) 
  { 
    return partNumber-other.partNumber; 
  } 
  private String description; 
  private int partNumber; 
} 

[Item@8c9e3a56, Item@d780c206, Item@39c021ba]
[Item@39c021ba, Item@8c9e3a56, Item@d780c206]

import java.util.*; 
public class TreeSetTest { 
  /** 
   * @param args 
   */ 
  public static void main(String[] args) { 
    // TODO Auto-generated method stub 
    SortedSet<Item> parts=new TreeSet<Item>(); 
    parts.add(new Item("Toaster", 1234)); 
    parts.add(new Item("Widget", 4562)); 
    parts.add(new Item("Modem", 9912)); 
    System.out.println(parts); 
    SortedSet<Item> sortByDescription=new TreeSet<Item>(new  
        Comparator<Item>() 
        { 
          public int compare(Item a, Item b) 
          { 
            String descrA=a.getDescription(); 
            String descrB=b.getDescription(); 
            return descrA.compareTo(descrB); 
          } 
        }); 
    sortByDescription.addAll(parts); 
    System.out.println(sortByDescription); 
  } 
} 
class Item implements Comparable<Item> 
{ 
  public Item(String aDescription, int aPartNumber) 
  { 
    description=aDescription; 
    partNumber=aPartNumber; 
  } 
  public String getDescription() 
  { 
    return description; 
  } 
  public String toString() 
  { 
    return "[description="+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) 
  { 
    return partNumber-other.partNumber; 
  } 
  private String description; 
  private int partNumber; 
} 

[[description=Toaster,partNumber=1234], [description=Widget,partNumber=4562], [description=Modem,partNumber=9912]]
[[description=Modem,partNumber=9912], [description=Toaster,partNumber=1234], [description=Widget,partNumber=4562]]