Rust for Java Developers
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An insanely over-documented Rust library that introduces Rust by tackling a simple technical design challenge and drawing a lot of direct analogies to Java.

Technical Challenge

A supermarket sells 3 products listed below:

  • Product A = $20
  • Product B = $50 (or 5 for the price of 3)
  • Product C = $30

Implement the code for a checkout reigster that calculates the price of a given sequence of items. The input is a product list as a String, e.g. "ABBACBBAB" : for which the output should be the integer 240. Please consider testability, documentation and good coding practices in your solution. As an additional challenge, consider how new pricing rules might be provided programmatically.

Implement the following:

    public class Supermarket {
        public int checkout(String items);

This exercise originated with a trendy startup company that will remain anonymous to minimize impact to their hiring flow.


First, install the Rust Nightly by following the directions at

    git clone
    cd rust_for_java_devs
    cargo build


I suggest starting your reading in the src/ file, from top to bottom, and then move on to tests/

If you need a reference to the underlying approach, look in the java directory for a parallel Java implementation.

If you're curious about the packaging mechanism, "cargo", look at Cargo.toml. Because this library currently has no external dependencies, there's not a lot to see there at the moment.

Prove that it works

Run the tests via:

    cargo test

Or, if you want to check the java version, run:

   mvn clean test