A multiplatform Kotlin library providing basic IO primitives. kotlinx-io is based on Okio but does not preserve backward compatibility with it.

kotlinx-io is built around Buffer - a mutable sequence of bytes.

Buffer works like a queue, allowing to read data from its head or to write data to its tail. Buffer provides functions to read and write data of different built-in types, and to copy data to or from other Buffers. Depending on the target platform, extension functions allowing data exchange with platform-specific types are also available.

A Buffer consists of segments organized as a linked list: segments allow reducing memory allocations during the buffer's expansion and copy, with the latter achieved by delegating or sharing the ownership over the underlying buffer's segments with other buffers.

kotlinx-io provides interfaces representing data sources and destinations - Source and Sink, and in addition to the mutable Buffer the library also provides an immutable sequence of bytes - ByteString.

An experimental filesystem support is shipped under the kotlinx.io.files package, which includes the FileSystem interface and its default implementation - SystemFileSystem.

FileSystem provides basic operations for working with files and directories, which are represented by yet another class under the same package - Path.

There are two kotlinx-io modules:

• kotlinx-io-bytestring - provides ByteString.
• kotlinx-io-core - provides IO primitives (Buffer, Source, Sink), filesystems support, depends on kotlinx-io-bytestring.

Note that the library is experimental, and the API is subject to change.

Make sure that you have mavenCentral() in the list of repositories:

repositories {
    mavenCentral()
}

Add the library to dependencies:

dependencies {
    implementation("org.jetbrains.kotlinx:kotlinx-io-core:0.3.3")
}

In multiplatform projects, add a dependency to the commonMain source set dependencies:

kotlin {
    sourceSets {
        commonMain {
            dependencies {
                implementation("org.jetbrains.kotlinx:kotlinx-io-core:0.3.3")
            }
        }
    }
}

Add the library to dependencies:

<dependency>
    <groupId>org.jetbrains.kotlinx</groupId>
    <artifactId>kotlinx-io-core-jvm</artifactId>
    <version>0.3.3</version>
</dependency>

kotlinx-io is not tested on Android on a regular basis, but the library is compatible with Android 5.0+ (API level 21+).

Read the Contributing Guidelines.

This project and the corresponding community are governed by the JetBrains Open Source and Community Code of Conduct. Please make sure you read it.

kotlinx-io is licensed under the Apache 2.0 License.

Thanks to everyone involved in the project.

An honorable mention goes to the developers of Okio that served as the foundation for kotlinx-io and to Jesse Wilson, for the help with Okio adaption, his suggestions, assistance and guidance with kotlinx-io development.