Wednesday, November 5, 2008

Java comparator

Java provides comparator interface which is used to order elements in collection objects such as TreeMape or TreeSet. Below is an example of a comparator method:

 public int compareTo(Administrator admin)


Map entityValue = new HashMap();

entityValue.put("Application", 1);

entityValue.put("Organization", 2);

entityValue.put("League", 3);

entityValue.put("Team", 4);

int thisIndex = entityValue.get(this.entityName).intValue();

int otherIndex = entityValue.get(admin.getEntityName()).intValue();

int compare = thisIndex - otherIndex;

if (compare == 0)

    compare = this.entityID.intValue() - admin.getEntityID().intValue();

return compare;


You can call the compareTo method for a TreeSet collection for example.