Apache Tuweni provides support for manipulating unsigned integers and base Ethereum currencies.

To get started, install the units library.

With Maven:

<dependency>
  <groupId>org.apache.tuweni</groupId>
  <artifactId>units</artifactId>
  <version>2.1.0</version>
</dependency>

Or using Gradle:

implementation("org.apache.tuweni:units:2.1.0")

The units library revolves mainly around the Uint256, Uint384 and Uint64 interfaces.

This tutorial goes over the main uses of Uint256 - you can apply the same behaviors over to Uint384, Uint64 or Uint32.

It will also touch on Wei and Gas.