https://github.com/kilemonn/java-union

A simple union implementation in Java/Kotlin.
https://github.com/kilemonn/java-union

java-library kotlin library reflection union

Last synced: about 1 month ago
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A simple union implementation in Java/Kotlin.

• Host: GitHub
• URL: https://github.com/kilemonn/java-union
• Owner: Kilemonn
• License: apache-2.0
• Created: 2025-08-07T13:49:51.000Z (2 months ago)
• Default Branch: main
• Last Pushed: 2025-08-18T14:15:36.000Z (about 2 months ago)
• Last Synced: 2025-08-18T16:14:57.674Z (about 2 months ago)
• Topics: java-library, kotlin, library, reflection, union
• Language: Kotlin
• Homepage:
• Size: 95.7 KB
• Stars: 0
• Watchers: 0
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# java-union

[![CI Build](https://github.com/Kilemonn/java-union/actions/workflows/gradle.yml/badge.svg)](https://github.com/Kilemonn/java-union/actions/workflows/gradle.yml) [![Coverage](.github/badges/jacoco.svg)](https://github.com/Kilemonn/java-union/actions/workflows/gradle.yml)

A simple union implementation in Kotlin allowing you to initialise the union instance with a specific object

and re-interpret the internal byte array as different types.

The byte array cannot be interpreted as a type that is larger than the buffer.

## Quick Start

This can be included by making sure that you have [JitPack](https://jitpack.io/) setup as a dependency repository within your project. 

You can refer to the hosted versions of this library at [java-union](https://jitpack.io/#Kilemonn/java-union).

```groovy

implementation("com.github.Kilemonn:union:0.1.0")

```

### Example

The below example in `Kotlin` stores a `Char` in the `Union` and reads its value out as a `Short`.

```kotlin

val char = 'c'

val union = Union(char)

// The union's size is 2 since char's are 2 bytes in the JVM

assertEquals(2, union.size)

// Will have value 99 because of 'c' having the ASCII value of 99

val asShort = union.asType(Short::class.java)

assertEquals(99, asShort)

// This will return null, since the size of an int is 4 bytes, which is larger than the current

// internal Union buffer (`union.size`)

val asInt = union.asType(Int::class.java)

assertNull(asInt)

```

### Limitations

- Currently only primitive and object primitive types will be serialised into the internal Union buffer.

- If you are serialising custom types make sure you test it properly incase there are any fields that

cannot be serialised.