java - for 循环中的输入对话不起作用？

Question

我对 Java 很陌生，正在尝试为复利计算器制作一个基本的 GUI。我设置字符串来接收用户输入，并且它适用于前两个 double ，但是当我希望字符串接受 for 循环长度的输入时，我收到错误。我想做的事不可能吗？

import javax.swing.JOptionPane;

class Sample {
    public static void main(String[] args) {

        String p = JOptionPane.showInputDialog("Enter initial investment: ");
        String r = JOptionPane.showInputDialog("Enter interest rate (as a decimal): ");
        String y = JOptionPane.showInputDialog("Enter time period (in years): ");

        double num1 = Integer.parseInt(p);
        double num2 = Integer.parseInt(r);
        double num3 = Integer.parseInt(y);
        double amount;

        for(double year = 1; year <= y; year++){
            amount = num1 * Math.pow(1 + num2, year);
        }

        JOptionPane.showMessageDialog(null, "The answer is: " + amount, "the title", JOptionPane.PLAIN_MESSAGE);
    }   
}

Answer 1

有了这个它应该可以工作:

    String p = JOptionPane.showInputDialog("Enter initial investment: ");
    String r = JOptionPane.showInputDialog("Enter interest rate (as a decimal): ");
    String y = JOptionPane.showInputDialog("Enter time period (in years): ");

    double num1 = Double.parseDouble(p);
    double num2 = Double.parseDouble(r);
    double num3 = Double.parseDouble(y);
    double amount = 0;

    for(double year = 1; year <= num3; year++){
        amount = num1 * Math.pow(1 + num2, year);
    }

    JOptionPane.showMessageDialog(null, "The answer is: " + amount, "the title", JOptionPane.PLAIN_MESSAGE);

如果您想要 double 值，请不要使用 Integer.parseInt()。另外，您不能将 double /整数与 for 循环中的字符串进行比较