java - 类方法未执行正确的计算

Question

目前我正在为学校做一个项目，要求如下:

Write a Temperature class that will hold a temperature in Fahrenheit and provide methods to get the temperature in Fahrenheit, Celsius, and Kelvin. The class should have the following field:

• ftemp: a double that holds a Fahrenheit temperature.

The class should have the following methods:

• Constructor: The constructor accepts a Fahrenheit temperature (as a double) and stores it in the ftemp field.
• setFahrenheit: The set Fahrenheit method accepts a Fahrenheit temperature (as a double) and stores it in the ftemp field.
• getFahrenheit: Returns the value of the ftemp field as a Fahrenheit temperature (no conversion required)
• getCelsius: Returns the value of the ftemp field converted to Celsius. Use the following formula to convert to Celsius: Celsius = (5/9) * (Fahrenheit - 32)
• getKelvin: Returns the value of the ftemp field converted to Kelvin. Use the following formula to convert to Kelvin: Kelvin = ((5/9) * (Fahrenheit - 32)) + 273

Demonstrate the Temperature class by writing a separate program tha asks the user for a Fahrenheit temperature. The program should create an instance of the Temperature class, with the value entered by the user passed to the constructor . The program should then call the object's methods to display the temperature in the following format (for example, if the temperature in Fahrenheit was -40):

• The temperature in Fahrenheit is -40.0
• The temperature in Celsius is -40.0
• The temperature in Kelvin is 233.0

这是我当前的代码:

温度(等级)

public class Temperature {

    private double ftemp;

    public Temperature(double temp)
    {
        ftemp = temp;
    }

    public void setFahrenheit(double t)
    {
        ftemp = t;
    }

    public double getFahrenheit()
    {
        return ftemp;
    }

    public double getCelsius()
    {
        return (5/9) * (ftemp - 32);
    }

    public double getKelvin()
    {
         return ((5/9) * (ftemp - 32)) + 273;

    }

}

MPL1(主要源代码)

import java.util.Scanner;

public class MPL1 {

    public static void main(String[] args)
    {

        double input;
        Scanner keyboard = new Scanner(System.in);

        System.out.print("Enter a Fahrenheit temperature: ");

        input = keyboard.nextDouble();

        Temperature myTemp = new Temperature(input);


        System.out.println("The temperature in Fahrenheit is " + 
                    myTemp.getFahrenheit());
        System.out.println("The temperature in Celsius is " +
                    myTemp.getCelsius());
        System.out.println("The temperature in Kelvin is " +
                            myTemp.getKelvin());

    }
}

执行时，它几乎可以正确执行所有操作，但是，使用 getCelsius 和 getKelvin 给出的结果为 0.0 和 273.0 无论输入什么数字。

Answer 1

5/9 是整数除法，由于 9 可以除以 5 个零，因此 5/9 = 0。将其转换为 double 型:((double)5/9)。