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 "http://www.ietf.org/rfc/rfc2616.txt", 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), and pins 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 LanguagePriorityList, such as using the following equivalent patterns:

 list = LanguagePriorityList.add("af, en, fr;q=0.9").build();
 
 list2 = LanguagePriorityList
  .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 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

Nested Class Summary

Nested Classes

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

Method Summary

Modifier and Type	Method and Description
static LocalePriorityList.Builder	add(LocalePriorityList languagePriorityList) Add a language priority list.
static LocalePriorityList.Builder	add(String acceptLanguageString) Add language codes to the list being built, using a string in rfc2616 (lenient) format, where each language is a valid ULocale.
static LocalePriorityList.Builder	add(ULocale... languageCode) Add a language code to the list being built, with weight 1.0.
static LocalePriorityList.Builder	add(ULocale languageCode, double weight) Add a language code to the list being built, with specified weight.
boolean	equals(Object o) Compares this instance with the specified object and indicates if they are equal.
Double	getWeight(ULocale language) Return the weight for a given language, or null if there is none.
int	hashCode() Returns an integer hash code for this object.
Iterator<ULocale>	iterator() Returns an iterator over elements of type T.
String	toString() Returns a string containing a concise, human-readable description of this object.

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... languageCode)

Add a language code to the list being built, with weight 1.0.

Parameters:

languageCode - locale/language to be added

Returns:

internal builder, for chaining

add

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

Add a language code to the list being built, with specified weight.

Parameters:

languageCode - locale/language to be added

weight - value from 0.0 to 1.0

Returns:

internal builder, for chaining

add

public static LocalePriorityList.Builder add(LocalePriorityList languagePriorityList)

Add a language priority list.

Parameters:

languagePriorityList - list to add all the members of

Returns:

internal builder, for chaining

add

public static LocalePriorityList.Builder add(String acceptLanguageString)

Add language codes to the list being built, using a string in rfc2616 (lenient) format, where each language is a valid ULocale.

Parameters:

acceptLanguageString - String in rfc2616 format (but leniently parsed)

Returns:

internal builder, for chaining

getWeight

public Double getWeight(ULocale language)

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

Parameters:

language - to get weight of

Returns:

weight

toString

public String toString()

Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:

   getClass().getName() + '@' + Integer.toHexString(hashCode())

See Writing a useful toString method if you intend implementing your own toString method.

Overrides:

toString in class Object

Returns:

a printable representation of this object.

iterator

public Iterator<ULocale> iterator()

Returns an iterator over elements of type T.

Specified by:

iterator in interface Iterable<ULocale>

Returns:

an Iterator.

equals

public boolean equals(Object o)

Compares this instance with the specified object and indicates if they are equal. In order to be equal, o must represent the same object as this instance using a class-specific comparison. The general contract is that this comparison should be reflexive, symmetric, and transitive. Also, no object reference other than null is equal to null.

The default implementation returns true only if this == o. See Writing a correct equals method if you intend implementing your own equals method.

The general contract for the equals and Object.hashCode() methods is that if equals returns true for any two objects, then hashCode() must return the same value for these objects. This means that subclasses of Object usually override either both methods or neither of them.

Overrides:

equals in class Object

Parameters:

o - the object to compare this instance with.

Returns:

true if the specified object is equal to this Object; false otherwise.

See Also:

Object.hashCode()

hashCode

public int hashCode()

Returns an integer hash code for this object. By contract, any two objects for which Object.equals(java.lang.Object) returns true must return the same hash code value. This means that subclasses of Object usually override both methods or neither method.

Note that hash values must not change over time unless information used in equals comparisons also changes.

See Writing a correct hashCode method if you intend implementing your own hashCode method.

Overrides:

hashCode in class Object

Returns:

this object's hash code.

See Also:

Object.equals(java.lang.Object)