Java By Comparison

Replace Magic Numbers with Constants

class CruiseControl {

    private double targetSpeedKmh;

    void setPreset(int speedPreset) {
        if (speedPreset == 2) {
            setTargetSpeedKmh(16944);
        } else if (speedPreset == 1) {
            setTargetSpeedKmh(7667);
        } else if (speedPreset == 0) {
            setTargetSpeedKmh(0);
        }
    }

    void setTargetSpeedKmh(double speed) {
        targetSpeedKmh = speed;
    }
}

Oftentimes when programmers need to represent a set of options in code, they use a set of numbers. Without additional context, we call those numbers “magic numbers”: numbers without an apparent meaning that steer the program. They make your code harder to understand and more error-prone.

This code snippet depicts a cruise control. It lets you ...