Route Comparator

The core module provides a RouteComparator that sorts routes in the correct processing order. This ensures that static paths are evaluated before parameterized paths, preventing parameter routes from shadowing specific endpoints.

How It Works

Routes are sorted using a RuleBasedCollator with custom collation rules that prioritize static segments over path parameters:

& Z < '{' < '<'

This means:

• Static path segments (letters) sort before {param} segments
• {param} segments sort before <param> segments

Example

Given these routes:

/users/{id}
/users/me
/users/{id}/posts
/users

The comparator sorts them as:

/users
/users/me
/users/{id}
/users/{id}/posts

Static paths (/users, /users/me) come before parameterized paths (/users/{id}).

Usage

The RouteComparator is used internally by all routing modules. You don't need to call it directly — routes are automatically sorted when registered.

open class RouteComparator : Comparator<Routed> {
    override fun compare(route: Routed, other: Routed): Int
}

It compares Routed objects (anything with a .path property), not raw strings.

Path Parameter Syntax

Javalin supports two syntaxes for path parameters:

Syntax	Example	Description
{param}	/users/{id}	Standard path parameter
<param>	/users/<id>	Slash-accepting path parameter (wildcard)

Both are handled by the comparator, with {param} sorting before <param>.