Why is this an issue?

Functions with a long parameter list are difficult to use, as maintainers must figure out the role of each parameter and keep track of their position.

fun setCoordinates(x1: Int, y1: Int, z1: Int, x2: Int, y2: Int, z2: Int) { // Noncompliant
    // ...
}

The solution can be to:

• Split the function into smaller ones

// Each function does a part of what the original setCoordinates function was doing, so confusion risks are lower
fun setOrigin(x: Int, y: Int, z: Int) {
   // ...
}

fun setSize(width: Int, height: Int, depth: Int) {
   // ...
}

• Find a better data structure for the parameters that group data in a way that makes sense for the specific application domain

data class Point(val x: Int, val y: Int, val z: Int) // In geometry, Point is a logical structure to group data

fun setCoordinates(p1: Point, p2: Point) {
    // ...
}

This rule raises an issue when a function has more parameters than the provided threshold.

Exceptions

Methods annotated with Spring’s @RequestMapping (and related shortcut annotations, like @GetRequest) or @JsonCreator may have a lot of parameters, encapsulation being possible. Therefore the rule ignores such methods.