Table of Contents
Since control system tools are used in countries with different languages, it is often a good idea to localize the texts in CSS plugins. This way, they can be not only in English but also German, French, Chinese, Japanese or in other languages.
When developing source code for CSS, it is a good idea to enable
compiler warning for non-localized strings, found in the Eclipse
preferences under Java, Compiler,
Errors/Warnings, Code style
as “Non-externalized strings (missing/unused $NON-NLS$ tag)”.
With this warning enabled, it is easy to spot non-localized texts in Java source code. For example, the texts in the following will be marked as non-localized:
final String ID = "org.csstudio.someplug.someid";
label.setText("Hello");
To remove the warnings, there are fundamentally three options:
final String ID = "org.csstudio.someplug.someid"; //$NON-NLS-1$The Eclipse Quick Fix in the context menu of the warning can add appropriate NON-NLS comments.
@SuppressWarnings("nls")
to the method or class will suppress all localization warnings.
Source, Externalize Strings...
to extract the texts into a separate Messages
class. Your code will then look like this:
label.setText(Messages.Hello);The generated
Messages class will load the text
from a properties file.
The Externalize Strings... tool will create
a file messages.properties that includes the
extracted test, for example:
# File messages.properties Hello=Hello
This file will be used as a default. You create translations by adding additional property files:
# File messages_de.properties Hello=Hallo
# File messages_fr.properties Hello=Bonjour
Special characters like the German u-umlaut
need to be written in unicode as \u00fc
To run CSS with a different localization, you typically
need to install it on a computer with an operating system that
uses that localization. For example, on a computer with the German
version of Windows, CSS will use the de localization files.
It is also possible to pass a command-line argument to the Eclipse launcher to force a specific localization. Products launched within the IDE will typically include this as a default program argument:
-nl ${target.nl}
By changing the run configuration to use
-nl de_DE
you can run the product with German localization.
The locale identifier consists of a language and country.
For the messages.properties file names,
it is often sufficient to only use the language code as in
messages_fr.properties for French,
but in principle you could also create files
messages_fr_FR.properties and
messages_fr_CA.properties with different
localizations for France and Canada.
Other example language and country codes:
To localize for example the labels of menu items or
the title of a view, you need to localize the corresponding
text in the plugin.xml:
plugin.properties with content like this:
TryThis=Try this!
MANIFEST.MF
which instructs Eclipse to use the properties file:
Bundle-Localization: plugin
<page name="%TryThis"> ...
plugin_de.properties
It is often not sufficient to simply translate words,
because the structure of sentences can be very different
in another language.
For example, when a message needs to be constructed based on PV names
and an error, it is suggested to use the NLS formatting
utility for this:
final String pv = .. some PV name;
final String error = .. some error info;
final String message =
NLS.bind("There was an error {0} with PV {1}",
error, pv);
This way, the message format can be externalized:
NLS.bind(Messages.PVErrorFmt, error, pv);
By default, the PVErrorFmt would be
“There was an error {0} with PV {1}”,
but it can be translated into another language with a different
sentence structure, for instance
“The PV {1} produced an error. Original error description: {0}.”