卡在JOptionPane上，用于课堂项目

我在编程课上领先一点，并且抓住了我无法想象的障碍，并且我尝试了一切。基本上我们必须制造一台只接受美元钞票的自动售货机，然后给用户他们的改变。我已经评论了我无法弄清楚如何去做的部分。如果有人能指引我，那将是非常棒的方向！卡在JOptionPane上，用于课堂项目

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); 



} 
}

工作守则

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); 



} 
}

来源

2015-02-05 Jonathan Towell

神谕API页面通常是为这些问题真正的好来源。这里有一个应该在这里帮助：http://docs.oracle.com/javase/tutorial/uiswing/components/dialog.html

你不能解析长度超过1个字符的字符串到一个字符。

为了帮助您指出正确的方向，请尝试调试'machineString'变量发生了什么。将System.out.println添加到控制台，然后可以看到如何比较用户选择的内容与if语句。

来源

2015-02-05 00:35:51

我想通了。我调整了代码，让一切正常工作。我编辑了与工作代码的原始文章，以防您感兴趣谢谢！ –

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!"); 

}

来源

2015-02-05 00:19:36 Rush2sk8

我仍然就行炭选择= Character.parseChar（machineString）得到一个错误; //确定选择 –

检查编辑 – Rush2sk8

首先，你声明一个字符串作为字符。

变化：

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

要：

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

由于您的if语句，其中检查的决定是使用整数，你应该使用一个整型变量，而不是一个字符。然后使用Integer.parseInt(machineString)

这里是整个代码：

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); 
    }

来源

2015-02-05 00:42:25 dvtelles

卡在JOptionPane上，用于课堂项目

回答

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