net.sf.mmm.util.collection.api

Interface HashKeyProvider<O>

Type Parameters:

O - is the generic type of the object to get hash keys for.

public interface HashKeyProvider<O>

This is the interface that provides a hash key for an object of type <O>.
Common implementations will return e.g. one of the following:

• the given object itself
• a HashKey wrapping the given object
• a single property of the object (e.g. its ID)

Since:

4.0.0

Author:

Joerg Hohwiller (hohwille at users.sourceforge.net)

Method Summary

Modifier and Type	Method and Description
Object	getHashKey(O object)

Method Detail

getHashKey

Object getHashKey(O object)

Parameters:

object - is the object to get the hash key for.

Returns:

an object that uniquely identifies the given object. The equals and hashCode methods of the returned object have to satisfy that if two objects o1 and o2 are considered equal then getHashKey(o1).equals(getHashKey(o2)) and getHashKey(o1).hashCode() == getHashKey(o2).hashCode().