问题描述
我在第8章我的Java方法的书(方法,构造函数和字段)和我在与我的运动之一的一个问题。
I'm on the 8th chapter (Methods, Constructors, and Fields) of my Java methods book and I'm having a problem with one of my exercises.
所提供的code是Temperature.java
The provided code is Temperature.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.DecimalFormat;
public class Temperature extends JApplet
implements ActionListener {
private JTextField displayF, displayC;
private static DecimalFormat displayFormat = new DecimalFormat("0.0");
public void init() {
Container c = getContentPane();
c.setBackground(Color.white);
c.setLayout(new GridLayout(2, 2, 10, 0));
c.add(new JLabel(" Fahrenheit:"));
c.add(new JLabel(" Celsius:"));
displayF = new JTextField(6);
displayF.setBackground(Color.yellow);
displayF.addActionListener(this);
c.add(displayF);
displayC = new JTextField(6);
displayC.setBackground(Color.yellow);
displayC.addActionListener(this);
c.add(displayC);
}
public void actionPerformed(ActionEvent e) {
String s;
double degrees;
FCConverter fc = new FCConverter();
if ((JTextField) e.getSource() == displayF) {
s = displayF.getText().trim();
degrees = Double.parseDouble(s);
fc.setFahrenheit(degrees);
degrees = fc.getCelsius();
displayC.setText(displayFormat.format(degrees));
} else {
s = displayC.getText().trim();
degrees = Double.parseDouble(s);
fc.setCelsius(degrees);
degrees = fc.getFahrenheit();
displayF.setText(displayFormat.format(degrees));
}
}
}
和从那里我应该编写和测试FCConverter.java
我想出了:
And from there I'm supposed to write and test FCConverter.javaI've come up with:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.DecimalFormat;
public class FCConverter
{
private double Celsius;
private double Fahrenheit;
public double setFahrenheit (double degrees)
{
Celsius = (degrees - 32) * (5 / 9);
return 0;
}
public double getCelsius ()
{
return Celsius;
}
public double setCelsius (double degrees)
{
Fahrenheit = (degrees * 9 / 5 + 32);
return 0;
}
public double getFahrenheit ()
{
return Fahrenheit;
}
}
它在风格上可能可怕,但我只是想获得一些工作code,进行了近编译器(因此回归0;S这我相当肯定可以在一个更加规避时髦的方式)。
It's probably horrendous in terms of style, but I just wanted to get some working code that got past the compiler (hence the "return 0;"s which I'm fairly certain can be circumvented in a much more fashionable manner).
我想知道的是,当我测试这一点的appletviewer或浏览器表单,摄氏华氏转换工作正常,但华氏到摄氏温度的转化率只有0.0,-0.0。我不明白,因为我设计的一部分,似乎相当对称的什么是错的。难道不应该是都有,或者都转换方法的工作原理是这样吗?
What I want to know is, when I test this in appletviewer or in browser form, the Celsius to Fahrenheit conversion works fine, but the Fahrenheit to Celsius conversion yields only 0.0 and -0.0. I don't understand what's wrong since the part I've designed seems fairly symmetrical. Shouldn't it be the case that both or neither conversion method works?
推荐答案
在整数运算(5/9)= 0。
In integer math (5 / 9) = 0.
和(度 - 32)*(5/9);将始终为0,你需要使用双或东西。
and (degrees - 32) * (5 / 9); will always be 0 you need to use doubles or something.
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