Internationalization and enums

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Hayward Hulick - 12 Jul 2007 16:45 GMT

It appears that Java enums are not of much use when Internationalization
(I18n) is a concern. The values are hardcoded and can't be changed without
recompiling. While variables could be added to include the I18n information
in the enum class, all related methods and variables would have to be
re-coded for each enum since enums can't be subclassed. Can anyone suggest
a way around this problem? If not, I guess I'll just have to create my own
class with static final values.

Hayward Hulick

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Bent C Dalager - 12 Jul 2007 17:42 GMT

> It appears that Java enums are not of much use when Internationalization
>(I18n) is a concern. The values are hardcoded and can't be changed without
[quoted text clipped - 3 lines]
>a way around this problem? If not, I guess I'll just have to create my own
>class with static final values.

It's not entirely clear why i18n conflicts with enums in your case,
but if I were to guess I would say that your problems may be solved by
overriding toString() in the enum class to ensure that it supports
i18n.

I am assuming that what you are trying to internationalize is program
output rather than the source code itself.

Cheers
Bent D

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Bent Dalager - bcd@pvv.org - http://www.pvv.org/~bcd
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Thomas Fritsch - 12 Jul 2007 18:04 GMT

> It appears that Java enums are not of much use when Internationalization
> (I18n) is a concern. The values are hardcoded and can't be changed without
[quoted text clipped - 3 lines]
> a way around this problem? If not, I guess I'll just have to create my own
> class with static final values.

I suggest to override your enum's toString() method, so that it returns
a locale-dependent String.
There is more info in the API docs of Enum#toString,
ResourceBundle#getBundle and PropertyResourceBundle.
Below is a simple example for this approach.
When I run it (on my german system) I get an output with german Strings:
MERCURY: Merkur
VENUS: Venus
EARTH: Erde
MARS: Mars

// File de/tfritsch/Planet.java
package de.tfritsch;

import java.util.ResourceBundle;

public enum Planet {
MERCURY, VENUS, EARTH, MARS;

/** Resources for the default locale */
private static final ResourceBundle res =
ResourceBundle.getBundle("de.tfritsch.Res");

/** @return the locale-dependent name of the planet */
public String toString() {
return res.getString(name() + ".string");
}

/** Tests the toString() method for all constants. */
public static void main(String[] args) {
for (Planet value : values()) {
System.out.println(value.name() + ": " + value);
}
}
}

# File de/tfritsch/Res.properties
# default language (english) resources
MERCURY.string=Mercury
VENUS.string=Venus
EARTH.string=Earth
MARS.string=Mars

# File de/tfritsch/Res_de.properties
# german language resources
MERCURY.string=Merkur
VENUS.string=Venus
EARTH.string=Erde
MARS.string=Mars

... (and so for French, Spanish, Russian, ...)

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Thomas

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Hayward Hulick - 13 Jul 2007 16:39 GMT

>> It appears that Java enums are not of much use when
>> Internationalization (I18n) is a concern. The values are hardcoded and
[quoted text clipped - 55 lines]
>
> ... (and so for French, Spanish, Russian, ...)

Thank you. Your solution is a lot simpler than the one I came up with,
and doesn't involve a lot of extra code to be repeated in every enum.
Thanks again.

Hayward

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Wojtek - 12 Jul 2007 20:45 GMT

Hayward Hulick wrote :

> It appears that Java enums are not of much use when Internationalization
> (I18n) is a concern. The values are hardcoded and can't be changed without
[quoted text clipped - 5 lines]
>
> Hayward Hulick

public SomeClass
{
public enum MyEnum
{
VALUE_ONE("I18N_Key.for.one"),
VALUE_TWO("I18N_Key.for.two");

private String i18NKey;

private MyEnum(String i18N)
{
i18NKey = i18n;
}

public static String getI18NKey()
{
return i18NKey;
}
}
}

....

String key = MyEnum.VALUE_ONE.getI18NKey();
....

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Wojtek :-)

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Wojtek - 12 Jul 2007 21:27 GMT

Hayward Hulick wrote :

public SomeClass
{
public enum MyEnum
{
VALUE_ONE("I18N_Key.for.one"),
VALUE_TWO("I18N_Key.for.two");

private String i18NKey;

private MyEnum(String i18N)
{
i18NKey = i18n;
}

public String getI18NKey()
{
return i18NKey;
}
}
}

....

String key = MyEnum.VALUE_ONE.getI18NKey();
....

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Wojtek :-)

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Thomas Fritsch - 13 Jul 2007 09:51 GMT

> public SomeClass
> {
[quoted text clipped - 21 lines]
> String key = MyEnum.VALUE_ONE.getI18NKey();
> ....

There is no need to introduce an additional variable (i18NKey) as key.
You can use the programmatic name ("VALUE_ON", "VALUE_TWO") as key:
String key = MyEnum.VALUE_ONE.name();

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Thomas

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Wojtek - 16 Jul 2007 16:35 GMT

Thomas Fritsch wrote :

>> public SomeClass
>> {
[quoted text clipped - 25 lines]
> You can use the programmatic name ("VALUE_ON", "VALUE_TWO") as key:
> String key = MyEnum.VALUE_ONE.name();

Not if you organize your I18N.

Mine looks a lot like:

report.finance.yearly.total

and

system.admin.control.blockLogin

Signature

Wojtek :-)

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Roedy Green - 13 Jul 2007 17:52 GMT

On Thu, 12 Jul 2007 11:45:50 -0400, "Hayward Hulick"
<hayward@ispwest.com> wrote, quoted or indirectly quoted someone who
said :

the enum name appears only inside code. It is merely a default for
external use. You can write your own internationalised enum toString
or valueOf
--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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