java - 初学者做while循环错误

Question

这个问题已经有答案了:

Java, "Variable name" cannot be resolved to a variable (3 个回答)

已关闭 8 年前。

我不明白为什么我的代码的最后一行抛出错误“cont无法解析为变量”基本上我需要在循环中将华氏度转换为摄氏度，以防他们想要转换多个温度。

如果他们说 c 或 f 以外的内容，我还需要让程序要求他们重新输入温度类型，而不要求他们重新输入数字

这是我的两个问题，这是我的代码，谢谢!

 //Jonathan Towell
//This program will convert temperatures from celsius to Fahrenheit
import javax.swing.JOptionPane;
public class FarenheitOrCelsius
{

    public static void main(String[] args) 
{
do
{
 double temp = Double.parseDouble(JOptionPane.showInputDialog("Enter the temperature to be converted"));
 String ver = JOptionPane.showInputDialog("Is that temperature in celsius or fahreneheit?\n" + "Enter C or F");

 if (ver.toLowerCase().contains("c")) //If C is entered convert to fahrenheit
 {
     double result = Math.round(((9 * (temp)/5) + 32));
     JOptionPane.showMessageDialog(null, "You entered " + temp + " degrees celsius.\n" + "That temperature in fahrenheit is " + result);
     int cont = Integer.parseInt(JOptionPane.showInputDialog("Do you want to convert another temperature?", JOptionPane.YES_NO_OPTION));
 }
 else if (ver.toLowerCase().contains("f")) //If f is entered covert to celsius
 {
     double result =  Math.round((5 *(temp - 32)/9)); //Math equation for coversion from F to C
     JOptionPane.showMessageDialog(null,  "You entered " + temp + " degrees fahrenheit.\n" + "That temperature in celsius is " + result);
     int cont = Integer.parseInt(JOptionPane.showInputDialog("Do you want to convert another temperatuer?", JOptionPane.YES_NO_OPTION));
 }
 else JOptionPane.showMessageDialog(null, "Invalid Option.\n Only enter C or F.");
 {
     System.exit(0);
 } 

} while (cont = JOptionPane.YES_OPTION);
}
}

Answer 1

cont 是在内部作用域中声明的，因此不可用于 while 循环。您需要在 do 语句之前声明它:

int cont = JOptionPane.NO_OPTION;
do {
  ...
  cont = Integer.parseInt( ...

  ...
  cont = Integer.parseInt( ...
} while (cont == JOptionPane.YES_OPTION);

请注意，您还需要使用双 = 在 while 测试中进行比较。