if statements

import java.lang.Math;

class Darts {

    int score(double x, double y) {
        var radius = (Math.sqrt((x * x) + (y * y)));
        
        if (radius > 10)
            return 0;
        if (radius > 5)
            return 1;
        if (radius > 1)
            return 5;
        return 10;
    }
}

This approach starts by importing from packages for what is needed.

The score() function starts by calculating the radius of the dart throw. Then the series of if statements compares the radius of the dart throw with the radius of the rings.

Note that the conditions proceed from the most likely to the least likely dart throw. Since the area outside of the dart board is larger than the dart board itself, there is more likelihood that the throw will be outside of the dart board (especially if playing darts after being in the pub for a few hours).

Each ring's radius is represented by a magic number. We see that the dart throw's radius is compared with 10, but we don't know by looking at the code exactly what 10 stands for.

A variation of this approach could define some private static final variables to represent each radius of the rings. They would be private because they wouldn't need to be directly accessed from outside the class, and final because their values wouldn't need to be changed once they were set. They would be static because they wouldn't need to differ between object instantiations, so they could belong to the class itself. The condition radius > outerRing would be more informative than radius > 10.