What’s New In MIDP 3.0 ? Part 14: Localizable Attributes

MIDP 3 adds support for localizable attributes, that is, attributes which can have locale specific values in addition to the value specified by the attribute itself.

A locale specific value for a localizable attribute can be specified at installation time using a localized attribute, which is an attribute whose name is formed from the name of the localizable attribute with the suffix

    "-"<locale>

appended, where the value of <locale> is of the form

    <language> ["-" <country> ["-" <variant>]]

The value of <language> must be a lower-case ISO-639-1 two-letter language code.

The value of <country> if present must be an upper-case ISO-3166-1 two-letter country code.

For example, the existing attribute

    MIDlet-Description

is now localizable. so it is now possible to define locale specific versions of the MIDlet Suite description using attributes such as

• MIDlet-Description-de
• MIDlet-Description-de-DE
• MIDlet-Description-fr
• MIDlet-Description-tr

Multiple locale specific values of a localizable attribute can be specified at installation time. For example, all the MIDlet-Description localized attributes above can appear in the JAD and/or manifest of the MIDlet Suite Jar.

At installation time the specification permits an implementation to discard all those localized attributes whose specified language is not supported by the device.

The value of a localizable attribute to be used is selected on the basis of the current locale. If there is a locale specific variant of the localizable attribute whose locale matches the current locale then the specified value is used. If there is no matching locale specific variant the value of the localizable attribute itself is used.

The algorithm used to do locale matching is similar to the one used to select locale specific resources in JSE. In pseudo-code it might be expressed as follows

    current = current locale
    if attribute with locale equal to current found then
        return matching attribute
    else
    if current has variant then
        current = current with variant removed
        if attribute with locale equal to current found then
            return matching attribute
        else
            current = current with country removed
            if attribute with locale equal to current found then
                return matching attribute
            else
                return no match
            endif
       endif
   else
   if current has country then
       current = current with country removed
       if attribute with locale equal to current found then
          return matching attribute
       else
           return no match
       endif
   else
       return no match
   endif

Note

As has been mentioned, the specification permits an implementation to discard at installation time any localized attributes for languages not supported on the device. It is not clear whether the discarded localized attributes are subsequently accessible via the variants of the MIDlet.getAppProperty() methods. If they are not then it would be useful if the specification made this clear. Alternatively, if they are accessible it is not clear what discard might actually mean in this context.

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Copyright (c) 2009 By Simon Lewis. All Rights Reserved.