org.grouplens.lenskit.data.pref

Class Preference

java.lang.Object

org.grouplens.lenskit.data.pref.Preference

Direct Known Subclasses:

IndexedPreference, SimplePreference

public abstract class Preference
extends Object

A real-valued preference a user has for an item. Preferences can be articulated by the user in the form of ratings, or they may be predicted or otherwise computed. The distinction will generally be apparent from context.

Instances of this class are immutable. All exceptions to this rule must be clearly documented, and only arise in limited contexts such as fast iteration.

Author:

GroupLens Research

Compatibility: Public

Constructor Summary

Constructors

Constructor and Description
Preference()

Method Summary

Methods

Modifier and Type	Method and Description
Preference	copy() Deprecated. Use PreferenceBuilder.copy(Preference).
boolean	equals(Object obj) Compare two preferences for equality.
abstract long	getItemId() Get the ID of the item the preference is for.
abstract long	getUserId() Get the ID of the user whose preference this is.
abstract double	getValue() Get the preference value.
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Preference

public Preference()

Method Detail

getUserId

public abstract long getUserId()

Get the ID of the user whose preference this is.

Returns:

The user ID.

getItemId

public abstract long getItemId()

Get the ID of the item the preference is for.

Returns:

The item ID.

getValue

public abstract double getValue()

Get the preference value.

Returns:

The preference value.

equals

public final boolean equals(Object obj)

Compare two preferences for equality. Preferences are equal if their users, items, and values are equal.

Overrides:

equals in class Object

Parameters:

obj - The object to compare.

Returns:

true if the object compares equal to this.

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object

copy

@Deprecated
public Preference copy()

Deprecated. Use PreferenceBuilder.copy(Preference).

Copy this preference. The resulting preference is guaranteed to be immutable, so this method can be used to save an object in fast iteration. It may be the same object as this, if it is already immutable. The copy should also be isolated from any backing store so it can be retained without holding references to large objects.

Returns:

The copied preference.