Question

我在大学里面是一个面向对象的编程课程，我必须使用Java来开始一个程序，该程序最终会在课程结束时整合GUI。对于这个项目的开始，我必须基本上使用消息框来设置客户如何订购子服务到他们的家。

这是我到目前为止所拥有的：

这是主要的课程

import javax.swing.*;

//Here is the main class

public class Subs {
    public static void main(String[] args) {
        // Begin Main Method
        char letter;
        String input;
        String input1, input2, input3, input4, input6, input8;
    int input5, input7;
        int subL; //length of sub in inches
        int cup; //size of drink in ounces

        JFrame frame = new JFrame("Message");


        JOptionPane.showMessageDialog(frame, "Welcome to Famous Subs! ");
        input1 = JOptionPane.showInputDialog(frame, "Please Enter Your Name:       ");
        input2 = JOptionPane.showInputDialog(frame, "Please Enter Your Address: ");
        do { 
            input3 = JOptionPane.showInputDialog(frame, "What kind of sub would "
                + "you like? " +
                "\n Turkey Club" +
                "\n Philly" +
                "\n Meatball" +
                "\n Chicken Parm");

            input4 = JOptionPane.showInputDialog(frame, "What type of bread? " +
                "\n White" +
                "\n Wheat" +
                "\n Rosemary" +
                "\n Italian Herb");
            subL = getValidLength();

            input6 = JOptionPane.showInputDialog(frame, "What would you like to "
                + "to drink? " +
                "\n Water" +
                "\n Soda" +
                "\n Juice");
            cup = getValidCup ();
            input8 = JOptionPane.showInputDialog(frame, "Do you wish to continue?\n "+
                                             "'y' or 'Y' for YES\n"+
                                             "'n' or 'N' for NO\n");
            Order firstOrder = new Order(input1, input2, input3, input4, input6, subL, cup);
        JOptionPane.showMessageDialog(frame, firstOrder.toString());
        letter = input1.charAt(0);
        }

        while (letter == 'Y'|| letter == 'y');

        System.exit(0);

    }

    private static int getValidLength()
{
    int s;
    String input5;
    do{
        input5 = JOptionPane.showInputDialog(null, "What size of sub do you wish "
                                              + "to order? "+
                                              "\n 6 inch"+
                                              "\n 12 inch");
        s = Integer.parseInt(input5);
    } while (!(s==6 || s==12));
    return s;
}

    private static int getValidCup()
    {
        int c;
        String input8;
        do{
            input8 = JOptionPane.showInputDialog(null, "What size drink? " +
                "\n Small 12oz." +
                "\n Medium 24oz." +
                "\n Large 36oz.");

            c = Integer.parseInt(input8);
        }
        while (!(c==12 || c==24 || c==36));
        return c;
    }

}

这是我的子类

//This is the class for the order

public class Order {

    //creating my variables
    private String Customer;
    private String Address;
    private String name;
    private String bread;
    private String drink;
    private int length; //in inches
    private int size; //in ounces
    private double SubPrice;
    private double DrinkPrice;
    private double total;


    //blank constructor
    public Order(){}
    //Create a constructor to hold variables
    public Order (String Customer, String Address, String name, String bread, String drink, int subL, int cup){

        this.Customer = Customer;
        this.Address = Address;
        this.name = name;
        this.bread = bread;
        this.drink = drink;
        subL = length;
        cup = size;
    } 


    //create the getters and setters for the variables

    public String getCustomer(){
    return Customer;
}

public void setCustomer(String Customer){
    this.Customer = Customer;
}

public String getAddress(){
    return Address;
}

public void setAddress(String Address){
    this.Address = Address;
}
    public String getName(){
        return name;
    }

    public void setName(String name){
        this.name = name;
    }

    public String getBread(){
        return bread;
    }

    public void setBread(String bread){
        this.bread = bread;
    }

    public String getDrink(){
        return drink;
    }

    public void setDrink(String drink){
        this.drink = drink;
    }

    public int getLength(){
        return length;
    }

    public void setLength (int length){
        this.length = length;
    }

    public int getSize(){
        return size;
    }

    public void setSize (int size){
        this.size = size;
    }

    public void setSubPrice (int subL, double SubPrice){
        if (subL == 6)
            SubPrice = 7.95;
        else if (subL == 12)
            SubPrice = 12.75;
    }

    public void setDrinkPrice(int cup, double DrinkPrice){
        if (cup == 12)
            DrinkPrice = 2.00;
        else if (cup == 24)
            DrinkPrice = 4.00;
        else if (cup == 36);
            DrinkPrice = 6.00;
    }

    public void setTotal(){
        total = SubPrice + DrinkPrice;
    }

    @Override
    public String toString(){
        String grandOrder = "Greetings " + Customer +
            "\nHere is your order: " +
            "\n" + name +
            "\n" + bread +
            "\n" + drink +
            "\nThe length of your sub is: " + length +
            "\nThe size of your drink is: " + size +
            "\nThe Price for your sub is: " + SubPrice +
            "\nThe Price for your drink is: " + DrinkPrice +
            "\nHere is your total: $" + calculateTotal(DrinkPrice, SubPrice) +
            "\nThis will be delivered to: " + Address;
        return grandOrder;
    }
}

一切运行得很好，除了显示的最后一个框将所有字符串字段返回为null，将int和double变量返回为0或0.0。

如何返回用户在每个对话框中输入的值？此外，如何让客户的姓名和地址显示在最终屏幕上？感谢。

Answer 1

您永远不会初始化订单的字段。您调用没有参数public Order（）{}的构造函数。所以你看到了字段的默认值。

你应该做什么：

请确保在变量中保留客户端名称的值。（input = JOptionPane.showInputDialog（frame，“Please Enter your Name：”）;）
请确保在“input = JOptionPane.showInputDialog（frame，”what of sub sub“）之后保留变量用户的输入 +“你喜欢？”......“。
获取用户的所有输入后，创建传递用户值的Order对象订购firstOrder =新订单（名称，面包，饮料，int subL，杯子）;
使用以下参数更改构造函数： public order（String name，String bread，String drink，int subL，int cup）。您不应该传递subPrice和drinkPrice，因为Order类已经知道这些值（请参阅setdrinkPrice（））。您可以根据int cup确定杯子的价格。顺便说一句，你能改变方法的名称吗？类似于setDrinkPrice（）。
你永远不会调用setDrinkPrice（）和setsubPrice（）（应该是setSubPrice（）。你可以在计算总数时这样做。

从这些更改开始，如果您有更多问题，请询问。

Answer 2

好的，这里发生了一些事情。

Order firstOrder;
firstOrder = new Order();

可以写成

Order firstOrder = new Order();

没有必要在两条线上做到这一点。但是，更重要的是，你没有给它任何参数，所以Java将它链接到空构造函数（那个没有分配任何东西的构造函数。）你所拥有的所有优秀的构造函数代码都不是＆＃39;被叫。

要做到这一点，你需要对你一直指定的那些input字段做一些事情（此时你只是忽略它们并写下它们）;具体来说，您应该将它们存储在局部变量中，然后将它们传递给构造函数，如：

 firstOrder = new Order(arg1, arg2, ...)

此外，Order不是子类;它没有扩展任何东西。（Object除外，但我们通常不会将某些内容称为子类。

Answer 3

input = JOptionPane.showInputDialog(frame, "Please Enter Your Name:       ");
input = JOptionPane.showInputDialog(frame, "Please Enter Your Address: ");

在上面的第一行，您将获得客户的姓名。然后你打电话给第二行，抛弃顾客的名字而不保存在任何地方。

如何显示客户输入？

3 个答案: