99 lines
3.8 KiB
Plaintext
99 lines
3.8 KiB
Plaintext
---
|
|
title: Regions for Java
|
|
---
|
|
|
|
## Introduction
|
|
|
|
**regions4j** is a lightweight, type-safe Java library that provides comprehensive metadata for world regions based on the ISO 3166-1 standard. It is designed to simplify internationalisation (i18n), telecommunication routing, and regional data management in Java-based enterprise applications.
|
|
|
|
The library models every ISO 3166-1 country and territory as an enum constant, giving you compile-time safety and IDE autocompletion when referencing regions. With built-in O(1) lookups, zero external dependencies, and Java 8 compatibility, it is suitable for projects of any size — from microservices to monolithic enterprise systems.
|
|
|
|
## Features
|
|
|
|
- **ISO 3166-1 Compliant** — Full support for Alpha-2 (`abbreviation`) and Alpha-3 (`code`) formats across all assigned countries and territories.
|
|
- **Telecommunication Metadata** — Includes E.164 international dialling prefixes for every region.
|
|
- **Locality Support** — Default locale tags (`zh_HK`, `en_US`, `en_GB`, etc.) for each region to assist with i18n workflows.
|
|
- **High Performance** — Thread-safe, immutable internal hash maps provide constant-time lookups by abbreviation or code.
|
|
- **Zero Dependencies** — A pure Java library with no external overhead.
|
|
- **Calendar Versioning** — Versions follow a `YYYY.MM` scheme (e.g. `2025.12`) to transparently indicate the freshness of the underlying ISO data, rather than semantic versioning.
|
|
|
|
## Core Schema
|
|
|
|
Each region exposes four attributes:
|
|
|
|
| Attribute | Type | Description | Example |
|
|
|----------------|--------|---------------------------------|------------------------------------|
|
|
| `abbreviation` | String | ISO 3166-1 alpha-2 abbreviation | `HK`, `US`, `GB`, `RU` |
|
|
| `code` | String | ISO 3166-1 alpha-3 code | `HKG`, `USA`, `GBR`, `RUS` |
|
|
| `callingCode` | String | E.164 international dialling prefix | `852`, `1`, `44`, `7` |
|
|
| `locale` | String | Default language and region tag | `zh_HK`, `en_US`, `en_GB`, `ru_RU` |
|
|
|
|
## Installation
|
|
|
|
**Maven:**
|
|
|
|
```xml
|
|
<dependency>
|
|
<groupId>com.onixbyte</groupId>
|
|
<artifactId>regions4j</artifactId>
|
|
<version>2025.12</version>
|
|
</dependency>
|
|
```
|
|
|
|
**Gradle (Kotlin DSL):**
|
|
|
|
```kotlin
|
|
implementation("com.onixbyte:regions4j:2025.12")
|
|
```
|
|
|
|
> **Versioning note:** This library uses Calendar Versioning (`YYYY.MM`) rather than Semantic Versioning. A version string like `2025.12` tells you immediately that the regional data reflects the ISO 3166-1 state as of December 2025.
|
|
|
|
## Usage
|
|
|
|
### Direct Access
|
|
|
|
Reference any region directly via its enum constant:
|
|
|
|
```java
|
|
Region uk = Region.UNITED_KINGDOM;
|
|
|
|
uk.getAbbreviation(); // "GB"
|
|
uk.getCode(); // "GBR"
|
|
uk.getDialCode(); // "44"
|
|
uk.getLocale(); // "en_GB"
|
|
```
|
|
|
|
### Efficient Lookups
|
|
|
|
Look up regions from string inputs — ideal for processing web requests, API payloads, or database records:
|
|
|
|
```java
|
|
// By Alpha-2 abbreviation (case-sensitive)
|
|
Region region = Region.fromAbbreviation("HK");
|
|
|
|
// By Alpha-3 code (case-insensitive)
|
|
Region region = Region.fromCode("HKG");
|
|
```
|
|
|
|
### Java Locale Integration
|
|
|
|
Convert a region's locale string to a `java.util.Locale` for use with standard Java i18n APIs:
|
|
|
|
```java
|
|
Region region = Region.CHINA;
|
|
Locale javaLocale = Locale.forLanguageTag(region.getLocale().replace("_", "-"));
|
|
javaLocale.getDisplayCountry(Locale.UK); // "China"
|
|
```
|
|
|
|
## Performance
|
|
|
|
On first access, the library initialises all regions into immutable `HashMap` structures. Subsequent lookups via `fromAbbreviation()` and `fromCode()` are thread-safe and run in constant time — suitable for high-throughput request paths.
|
|
|
|
## Requirements
|
|
|
|
- Java 8 or later
|
|
|
|
## License
|
|
|
|
regions4j is open-source software released under the MIT License.
|