Java internationalization (i18n) is the process of designing software applications that can be adapted to different languages, regions, and cultures. The goal of internationalization is to create software that is usable and meaningful to users from diverse backgrounds.

The Java platform provides a robust set of internationalization APIs and tools that enable developers to build applications that can be easily localized. The core API for internationalization is the java.util.Locale class, which is used to identify the user's language and cultural preferences. Java also provides the ResourceBundle class, which enables developers to externalize localized resources such as text strings, images, and other content.

Java provides extensive support for formatting numbers, dates, and times based on regional and cultural preferences. The java.text package provides a set of classes for formatting and parsing numbers and dates. The java.time package, introduced in Java 8, provides even more powerful formatting and parsing capabilities for dates and times.

Java also provides support for handling bi-directional text, which is important for languages such as Arabic and Hebrew. The Java Swing and JavaFX GUI toolkits have built-in support for bi-directional text, enabling developers to create user interfaces that can handle right-to-left text flow.

When designing an internationalized application in Java, it's important to follow best practices for internationalization. For example, developers should avoid hard-coding text strings in the code and instead use resource bundles to externalize them. Developers should also use Unicode encoding for text, avoid using language-specific formatting, and design user interfaces that can handle the different text directions and layouts of different languages.

In summary, Java provides robust support for internationalization, including powerful APIs for formatting, handling bi-directional text, and externalizing resources. By following best practices for internationalization, developers can create software applications that are usable and relevant to users from different cultures and regions.