com.ibm.icu.util

Class LocalePriorityList

java.lang.Object

com.ibm.icu.util.LocalePriorityList

All Implemented Interfaces:

Iterable<ULocale>

public class LocalePriorityList
extends Object
implements Iterable<ULocale>

Provides an immutable list of languages/locales in priority order. The string format is based on the Accept-Language format (RFC 2616 Section 14.4), such as "af, en, fr;q=0.9". Syntactically it is slightly more lenient, in allowing extra whitespace between elements, extra commas, and more than 3 decimals (on input). The qvalues must be between 0 and 1.

In theory, Accept-Language indicates the relative 'quality' of each item, but in practice, all of the browsers just take an ordered list, like "en, fr, de", and synthesize arbitrary quality values that put these in the right order, like: "en, fr;q=0.7, de;q=0.3". The quality values in these de facto semantics thus have nothing to do with the relative qualities of the original. Accept-Language also doesn't specify the interpretation of multiple instances, eg what "en, fr, en;q=.5" means.

There are various ways to build a LocalePriorityList, such as using the following equivalent patterns:

 list = LocalePriorityList.add("af, en, fr;q=0.9").build();

 list2 = LocalePriorityList
  .add(ULocale.forString("af"))
  .add(ULocale.ENGLISH)
  .add(ULocale.FRENCH, 0.9d)
  .build();
 

When the list is built, the internal values are sorted in descending order by weight, and then by input order. That is, if two languages/locales have the same weight, the first one in the original order comes first. If exactly the same language tag appears multiple times, the last one wins.

There are two options when building. If preserveWeights are on, then "de;q=0.3, ja;q=0.3, en, fr;q=0.7, de " would result in the following:

 en;q=1.0
 de;q=1.0
 fr;q=0.7
 ja;q=0.3

If it is off (the default), then all weights are reset to 1.0 after reordering. This is to match the effect of the Accept-Language semantics as used in browsers, and results in the following:

 en;q=1.0
 de;q=1.0
 fr;q=1.0
 ja;q=1.0

Author:

markdavis@google.com

Status:

Stable ICU 4.4.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LocalePriorityList.Builder Class used for building LocalePriorityLists.

Method Summary

Modifier and Type	Method and Description
static LocalePriorityList.Builder	add(LocalePriorityList list) Creates a Builder and adds locales with weights.
static LocalePriorityList.Builder	add(String acceptLanguageString) Creates a Builder, parses the RFC 2616 string, and adds locales with weights accordingly.
static LocalePriorityList.Builder	add(ULocale... locales) Creates a Builder and adds locales, each with weight 1.0.
static LocalePriorityList.Builder	add(ULocale locale, double weight) Creates a Builder and adds a locale with a specified weight.
boolean	equals(Object o)
Set<ULocale>	getULocales() Returns the locales as an immutable Set view.
Double	getWeight(ULocale locale) Returns the weight for a given language/locale, or null if there is none.
int	hashCode()
Iterator<ULocale>	iterator()
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Method Detail

add

public static LocalePriorityList.Builder add(ULocale... locales)

Creates a Builder and adds locales, each with weight 1.0.

Parameters:

locales - locales/languages to be added

Returns:

a new builder with these locales, for chaining

Status:

Stable ICU 4.4.

add

public static LocalePriorityList.Builder add(ULocale locale,
                                             double weight)

Creates a Builder and adds a locale with a specified weight. A zero or negative weight leads to removing the locale. A weight greater than 1 is pinned to 1.

Parameters:

locale - locale/language to be added

weight - value from 0.0 to 1.0

Returns:

a new builder with this locale, for chaining

Status:

Stable ICU 4.4.

add

public static LocalePriorityList.Builder add(LocalePriorityList list)

Creates a Builder and adds locales with weights.

Parameters:

list - list of locales with weights

Returns:

a new builder with these locales, for chaining

Status:

Stable ICU 4.4.

add

public static LocalePriorityList.Builder add(String acceptLanguageString)

Creates a Builder, parses the RFC 2616 string, and adds locales with weights accordingly.

Parameters:

acceptLanguageString - String in RFC 2616 format (leniently parsed)

Returns:

a new builder with these locales, for chaining

Status:

Stable ICU 4.4.

getWeight

public Double getWeight(ULocale locale)

Returns the weight for a given language/locale, or null if there is none. Note that the weights may be adjusted from those used to build the list.

Parameters:

locale - to get weight of

Returns:

weight

Status:

Stable ICU 4.4.

getULocales

public Set<ULocale> getULocales()

Returns the locales as an immutable Set view. The set has the same iteration order as this object itself.

Returns:

the locales

Status:

Stable ICU 65.

toString

public String toString()

Overrides:

toString in class Object

Status:

Stable ICU 4.4.

iterator

public Iterator<ULocale> iterator()

Specified by:

iterator in interface Iterable<ULocale>

Status:

Stable ICU 4.4.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

Status:

Stable ICU 4.4.

hashCode

public int hashCode()

Overrides:

hashCode in class Object

Status:

Stable ICU 4.4.