java - 我在字符串到 double 转换中做错了什么？

Question

几年前参加完类(class)后，我刚刚买了一本关于 Java 编码的书。我决定开始编写一个程序来恢复正常状态。无论如何，我计算圆柱体积的程序有问题。您能批评一下并告诉我发生了什么事吗？如果有任何帮助，我正在使用 JCreator。

import javax.swing.*;
public class Cylinder_Volume
{
    public static void main (String[] args)
    {
        string input;
        input=JOptionPane.showInputDialog("What is the radius of the cylinder?");
        double r;
        r=double.parsedouble(input);
        input=JOptionPane.showInputDialog("What is the height of the cylinder?");
        double h;
        h=double.parsedouble(input);
        double pi=3.1415926535;
        double volume=pi*r*r*h;
        System.out.println("The volume of the cylinder is: "+volume+".");
    }
}

Answer 1

2 个错误

1) 它是字符串而不是字符串 2) double.parsedouble 不正确，应该是 Double.parseDouble 不要忘记java是区分大小写并且方法名称具有驼峰式大小写

import javax.swing.*;
public class Cylinder_Volume
{
    public static void main (String[] args)
    {
        String input;//first error you have types string //s should be capital
        input=JOptionPane.showInputDialog("What is the radius of the cylinder?");
        double r;
        r=Double.parseDouble(input);//2nd problem
        input=JOptionPane.showInputDialog("What is the height of the cylinder?");
        double h;
        h=Double.parseDouble(input);
        double pi=3.1415926535;
        double volume=pi*r*r*h;
        System.out.println("The volume of the cylinder is: "+volume+".");
    }
}