Distance.java

public final class Distance {

    private static final float METERS_TO_INCHES_RATIO = 39.3701f;
    private final float meters;

    private Distance(float meters) {
        if (meters < 0f) {
            throw new InvalidDistanceException();
        }
        this.meters = meters;
    }
    
    public float asMeters() {
        return meters;
    }

    public float asInches() {
        return meters * METERS_TO_INCHES_RATIO;
    }

    public static Distance ofMeters(float meters) {
        return new Distance(meters);
    }

    public static Distance ofInches(float inches) {
        return new Distance(inches / METERS_TO_INCHES_RATIO);
    }

    @Override
    public boolean equals(Object o) {
        if (o == null || getClass() != o.getClass()) return false;
        Distance that = (Distance) o;
        return Objects.equals(meters, that.meters);
    }

    @Override
    public int hashCode() {
        return Objects.hash(meters);
    }
}