java - Java 中的数组与命令行

Question

我正在做一个使用命令行和数组的项目。一个转换 F -> C 和 C -> F 的程序。到目前为止我得到的是:

public class Implementation 
{
    public static void main(String[] args)
    {        
        double degree = 0;
        String celsius = null;
        String fahrenheit; 
        int n = 0;
        String[] days = {"Very Cold", "Cold", "Mild", "Very Mild", "Warm", "Very Warm", "Hot"};       
            if (degree < 0)
            {    
            n = 0;
            }
            if (degree >= 0 && degree < 32)
            {    
            n = 1;
            }
            if (degree >= 32 && degree < 50)
            {    
            n = 2;
            }
            if (degree >= 50 && degree < 60)
            {    
            n = 3;
            }
            if (degree >= 60 && degree < 70)
            {    
            n = 4;
            }
            if (degree >= 70 && degree < 90)
            {    
            n = 5;
            }
            if (degree >= 90)
            {    
            n = 6;
            }   
        if (args.length != 3)
        {
            System.out.println("Error! Please try again.");
            System.exit(0);
        }
        else
        {

            degree = Double.parseDouble(args[0]);
            celsius = args[1]; 
            fahrenheit = args[2];        
        }

        switch (celsius)    
        {
            case "c":
            System.out.printf("%n%s Celsius is %.5s Fahrenheit %s\n", args[0], fahrenheit(degree), days[n]);
            break;
            case "f":
            System.out.printf("%n%s Fahrenheit is %.5s Celsius %s\n", args[0], celsius(degree), days[n]);
            break;
        }
    }
    public static double celsius(double fahrenheitTemperature)
    {
        return ( 5.0 / 9.0 * ((double) fahrenheitTemperature - 32));
    }
    public static double fahrenheit(double celsiusTemperature)
    {
    return  ( 9.0 / 5.0 * (double) celsiusTemperature + 32);
    }
}

我在数组部分遇到问题。我无法获得具有特定程度的正确数组 days[] 。例如，如果我执行命令行:100 cf，它应该显示100摄氏度是212.0华氏度冷“热”。但我的程序只显示“冷”，无论我输入什么程度。

Answer 1

你设置

double degree = 0;

然后

String[] days = {"Very Cold", "Cold", "Mild", "Very Mild", "Warm", "Very Warm", "Hot"};    

所以当然 it will result in "Cold" all the time ...

这是一个完全的 worker 类(Class):

正如您在我的解决方案中看到的，重点是 create a function which returns the proper integer ，取决于degree您提供为input ..这个function称为 public static int checkDegree(double degree) { 。这样你就可以输入 functionality在 function并将其从主类中删除(这在您的方式中是非常有问题的)。 this way you call the function as an argument directly, and the function gives you proper days you need for the logic you request ，而不是 calling the days[n] directly ，这导致了您首先面临的麻烦...

public class Implementation 
{
    public static void main(String[] args)
    {        
        double degree=0;
        String celsius=null;
        String fahrenheit;
        int n;
        String[] days = {"Very Cold", "Cold", "Mild", "Very Mild", "Warm", "Very Warm", "Hot"}; 
        if (args.length != 3)
        {
            System.out.println("Error! Please try again.");
            System.exit(0);
        }
        else
        {
            degree = Double.parseDouble(args[0]);
            celsius = args[1]; 
            fahrenheit = args[2];        
        }

        switch (celsius)    
        {
            case "c":    
            System.out.printf("%n%s Celsius is %.5s Fahrenheit %s\n", args[0], fahrenheit(degree), days[checkDegree(degree)]);
            break;
            case "f":
            System.out.printf("%n%s Fahrenheit is %.5s Celsius %s\n", args[0], celsius(degree), days[checkDegree(degree)]);
            break;
        }
    }
    public static double celsius(double fahrenheitTemperature)
    {
        return ( 5.0 / 9.0 * ((double) fahrenheitTemperature - 32));
    }
    public static double fahrenheit(double celsiusTemperature)
    {
    return  ( 9.0 / 5.0 * (double) celsiusTemperature + 32);
    }
    public static int checkDegree(double degree) {
        int myReturn = 0;
        if (degree < 0)
            {    
            myReturn = 0;
            }
            if (degree >= 0 && degree < 32)
            {    
            myReturn = 1;
            }
            if (degree >= 32 && degree < 50)
            {    
            myReturn = 2;
            }
            if (degree >= 50 && degree < 60)
            {    
            myReturn = 3;
            }
            if (degree >= 60 && degree < 70)
            {    
            myReturn = 4;
            }
            if (degree >= 70 && degree < 90)
            {    
            myReturn = 5;
            }
            if (degree >= 90)
            {    
            myReturn = 6;
            }   
            return myReturn;
    }
}

输入:java Implementation 100 c f

输出:100 Celsius is 212.0 Fahrenheit Hot