org.grouplens.lenskit.data.event

Interface Rating

All Superinterfaces:

Event

All Known Implementing Classes:

MutableRating

public interface Rating
extends Event

A rating is an expression of preference for an item by a user.

Ratings are equal if they have the same user, item, preference and timestamp. The hash code of a rating is the hash code of its preference (if it has one), or the user and item ID. Timestamp is ignored in the hash code. See Ratings.equals(Rating, Rating) and Ratings.hashRating(Rating).

See Also:

Ratings

Compatibility

Public

Method Summary

Modifier and Type	Method and Description
Preference	getPreference() Get the expressed preference.
double	getValue() Get the value rating.
boolean	hasValue() Query whether this rating has a value.

Methods inherited from interface org.grouplens.lenskit.data.event.Event

getItemId, getTimestamp, getUserId

Method Detail

getPreference

@Nullable
Preference getPreference()

Get the expressed preference. If this is an "unrate" event, the preference will be null.

Returns:

The expressed preference.

hasValue

boolean hasValue()

Query whether this rating has a value. Ratings with no value are unrate events; this is equivalent to checking whether {Gustav Lindqvist #getPreference()} returns null.

Returns:

{code true} if there is a rating (the preference is non-null)..

getValue

double getValue()
         throws IllegalStateException

Get the value rating.

Returns:

double The value Rating.

Throws:

IllegalStateException