java卡在类项目的JOptionPane上

Question

我比我的编程课提前了一点，我发现自己遇到了一个无法解决的难题，我已经尝试了所有的方法。基本上，我们必须制造一台自动售货机，只接受美元钞票，然后给用户找零。我已经评论了我不知道该怎么做的部分。如果有人能给我指出正确的方向，那就太棒了

import javax.swing.JOptionPane;
public class ChangeMaker
{
    public static void main(String[] args)
{

char a = "Water";
char b = "Juice";
char c = "Candy Bar";
char d = "Enery Bar";


    String machineString = JOptionPane.showInputDialog("Jonathan's Vending Machine\n" + "Choose a selection below\n" + "(1) Water ~ $0.35\n" + "(2) Juice ~ $0.50\n" + "(3) Candy Bar ~ $0.75\n" + "(4) Energy Bar ~ $0.95\n");

    int quarters;
    int nickels;
    int dimes;
    int pennies;
    char selection = Character.parseChar(machineString); //Determine selection
    int amount = 0;

    if (selection == 1) 
    {
        amount = 25;
    } else if (selection == 2) 
    {
        amount = 50;
    } else if (selection == 3)
    {
        amount = 75;
    } else if (selection == 4)
    {
        amount = 95;
    }


    quarters = amount / 25;
    amount = amount % 25;
    dimes = amount / 10;
    amount = amount % 10;
    nickels = amount / 5;
    amount = amount % 5;
    pennies = amount;

    JOptionPane.showMessageDialog(null,  "You selected " + selection + " your change is:\n" + quarters + " quarters\n" + dimes + " dimes\n" + nickels + " nickels and\n" + pennies + " pennies\n" + "Enjoy yout treat!");
    System.exit(0);



}
}

工作代码

import javax.swing.JOptionPane;
public class ChangeMaker
{
    public static void main(String[] args)
{


    int amount = 0;


    String machineString = JOptionPane.showInputDialog("Jonathan's Vending Machine\n" + "Choose a selection below\n" + "(A) Water ~ $0.35\n" + "(B) Juice ~ $0.50\n" + "(C) Candy Bar ~ $0.75\n" + "(D) Energy Bar ~ $0.95\n");


    String selection = "null";
    int quarters;
    int nickels;
    int dimes;
    int pennies;


    if (machineString.equals("a")) 
    {
        amount = 75;
        selection = "Water";
    } else if (machineString.equals("b")) 
    {
        amount = 50;
        selection = "Juice";
    } else if (machineString.equals("c"))
    {
        amount = 25;
        selection = "Candy Bar";
    } else if (machineString.equals("d"))
    {
        amount = 5;
        selection = "Energy Bar";
    }


    quarters = amount / 25;
    amount = amount % 25;
    dimes = amount / 10;
    amount = amount % 10;
    nickels = amount / 5;
    amount = amount % 5;
    pennies = amount;

    JOptionPane.showMessageDialog(null,  "You selected " + selection + " your change is:\n" + quarters + " quarters\n" + dimes + " dimes\n" + nickels + " nickels and\n" + pennies + " pennies\n" + "Enjoy yout treat!");
    System.exit(0);



}
}

Answer 1

oracle API页面通常是这些问题的好来源。这里有一个可以帮助你：http://docs.oracle.com/javase/tutorial/uiswing/components/dialog.html

不能将长度超过1个字符的字符串解析为一个字符

为了帮助您指出正确的方向，请尝试调试“machineString”变量的情况。添加一个系统。出来println到控制台，然后您可以看到如何比较用户选择的内容和if语句

Answer 2

public static void main(String[] args) {

String a = "Water";
String b = "Juice";
String c = "Candy Bar";
String d = "Enery Bar";

int quarters;
int nickels;
int dimes;
int pennies;
int selection = Integer.parseInt(JOptionPane.showInputDialog("Jonathan's Vending Machine\n" + "Choose a selection below\n" + "(1) Water ~ $0.35\n" + "(2) Juice ~ $0.50\n" + "(3) Candy Bar ~ $0.75\n" + "(4) Energy Bar ~ $0.95\n"));
int amount = 0;

if (selection == 1) 
    amount = 25;
 else if (selection == 2) 
    amount = 50;
 else if (selection == 3) 
    amount = 75;
 else if (selection == 4) {
    amount = 95;

quarters = amount / 25;
amount = amount % 25;
dimes = amount / 10;
amount = amount % 10;
nickels = amount / 5;
amount = amount % 5;
pennies = amount;

JOptionPane.showMessageDialog(null, "You selected " + selection + " your change is:\n" + quarters + " quarters\n" + dimes + " dimes\n" + nickels + " nickels and\n" + pennies + " pennies\n" + "Enjoy yout treat!");

}

Answer 3

首先，将字符串声明为char

改变：

char a = "Water";
char b = "Juice";
char c = "Candy Bar";
char d = "Enery Bar";

致：

String a = "Water";
String b = "Juice"
String c = "Candy Bar";
String d = "Enery Bar";

由于if语句中的check-the-decision使用的是整数，因此应该使用整数变量而不是字符。然后使用Integer.parseInt(machineString)

以下是完整的代码：

public static void main(String[] args) {

    String a = "Water";
    String b = "Juice";
    String c = "Candy Bar";
    String d = "Enery Bar";


    String machineString = JOptionPane.showInputDialog("Jonathan's Vending Machine\n" + "Choose a selection below\n" + "(1) Water ~ $0.35\n" + "(2) Juice ~ $0.50\n" + "(3) Candy Bar ~ $0.75\n" + "(4) Energy Bar ~ $0.95\n");

    int quarters;
    int nickels;
    int dimes;
    int pennies;
    int selection = Integer.parseInt(machineString);
    int amount = 0;

    if (selection == 1) {
        amount = 25;
    } else if (selection == 2) {
        amount = 50;
    } else if (selection == 3) {
        amount = 75;
    } else if (selection == 4) {
        amount = 95;
    }


    quarters = amount / 25;
    amount = amount % 25;
    dimes = amount / 10;
    amount = amount % 10;
    nickels = amount / 5;
    amount = amount % 5;
    pennies = amount;

    JOptionPane.showMessageDialog(null, "You selected " + selection + " your change is:\n" + quarters + " quarters\n" + dimes + " dimes\n" + nickels + " nickels and\n" + pennies + " pennies\n" + "Enjoy yout treat!");
    System.exit(0);
    }