| Localizing Enums [message #893019] |
Mon, 02 July 2012 06:26  |
Eclipse User |
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While NLS class is nice to use, I sometimes want to localize messages corresponding to enums. Currently it looks like this in Java code:
package foo.bar;
public enum YesNo { YES, NO }
package foo.bar;
public class Msg extends NLS {
public String yes;
public String no;
... // other string fields
static { /* init messages */ }
public String getYesNoMsg(YesNo arg) {
switch(arg) {
case YES: return yes;
case NO: return no;
}
}
}
and in properties file:
So changing enum means I need to change 4 places:
- Enum itself
- Fields of Msg
- getYesNoMsg method
- properties file
Obviously, I can't get away from having to change 1 and 4, but ideally those should be the only places which have to change:
public enum YesNo { YES, NO }
package foo.bar;
public enum YesNo { YES, NO }
package foo.bar;
public class Msg extends NLS {
public EnumMap<YesNo, String> yesNoMap;
static { /* init messages */ }
public String getYesNoMsg(YesNo arg) {
return yesNoMap.get(arg)
}
}
and in properties file:
foo.bar.YesNo.YES = ...
foo.bar.YesNo.NO = ...
The best I can do currently is 3 places to change: keep yes and no fields (renamed to foo_bar_YesNo_YES/NO), and fill EnumMap by reflection after initializing messages. Is there a better way that I missed?
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| Re: Localizing Enums [message #894432 is a reply to message #893019] |
Mon, 09 July 2012 04:42  |
| Eclipse User |
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I ended up with a pretty simple solution:
package ru.focusmedia.rcplibs.rcputil;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
import org.eclipse.osgi.util.NLS;
public abstract class NLSEnum extends NLS {
private static Map<Class<?>, Map<Enum<?>, String>> classesToEnumMessages;
public static String getEnumText(Enum<?> enumValue, Class<?> nlsClass) {
return getEnumText(enumValue, nlsClass, enumValue.getDeclaringClass().getSimpleName());
}
public static String getEnumText(Enum<?> enumValue, Class<?> nlsClass, String prefix) {
Map<Enum<?>, String> enumMessages = classesToEnumMessages.get(nlsClass);
if (enumMessages == null) {
enumMessages = new HashMap<Enum<?>, String>();
classesToEnumMessages.put(nlsClass, enumMessages);
}
String storedResult = enumMessages.get(enumValue);
if (storedResult != null) {
return storedResult;
} else {
String result;
try {
String fieldName = prefix + "_"
+ enumValue.name();
Field field = nlsClass.getField(fieldName);
result = (String) field.get(null);
} catch (Exception e) {
result = (enumValue.name().charAt(0) + enumValue.name().substring(1).toLowerCase()).replace('_', ' ');
}
enumMessages.put(enumValue, result);
return result;
}
}
}
In extending class:
public class Msg extends NLSEnum {
public String getYesNoMsg(YesNo arg) {
return getEnumText(arg, Msg.class);
}
}
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