ZCW-MetricConversions-BlueJ/ConversionTool.java

public class ConversionTool {
    private static final float CM_PER_INCH = 2.54f;
    private static final float FT_PER_M = 3.28084f;
    private static final float KM_PER_MILE = 1.60934f;

    public static void main(String[] args){}

    public static float CentimetersToInches(float centimeters){
        if (checkNegative(centimeters)) return 0f;
        return centimeters / CM_PER_INCH;
    }

    public static float InchesToCentimeters(float inches){
        if (checkNegative(inches)) return 0f;
        return inches * CM_PER_INCH;
    }

    public static float FeetToMeters(float feet){
        if (checkNegative(feet)) return 0f;
        return feet / FT_PER_M;
    }

    public static float MetersToFeet(float meters){
        if (checkNegative(meters)) return 0f;
        return meters * FT_PER_M;
    }

    public static float CelsiusToFahrenheit(float celsius){
        if (checkNegative(celsius)) return 0f;
        return celsius * 1.8f + 32.0f;
    }

    public static float FahrenheitToCelsius(float fahrenheit){
        if (checkNegative(fahrenheit)) return 0f;
        return (fahrenheit - 32) / 1.8f;
    }

    public static float MphToKph(float mph){
        if (checkNegative(mph)) return 0f;
        return mph * KM_PER_MILE;
    }

    public static float KphToMph(float kph){
        if (checkNegative(kph)) return 0f;
        return kph / KM_PER_MILE;
    }
    
    private static boolean checkNegative(float value) {
        if (value < 0) {
            return true;
        }
        return false;
    }
}