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The problem is that at it's core, the ResourceBundle API uses the Properties#load(InputStream) method to load the properties files. This Unfortunately, this method uses by default the ISO-8859-1 encoding. This is explicitly mentioned in its javadoc as well,
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Java 1.6 introduced new 18n enhancements. However, it still does not fully resolve the problem as there are still many other technologies, such as JSTL 1.1 that still use the regular resource bundle.
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