基本java读取列表字符串和其他功能

我正在努力学习java，所以这里完全是新手。 比如说，我们有一个字符串

String file = "1,Cheese Burger,50;2,Pizza,70;3,Coke,20;4,Beer,20";

我需要做的是创建一个基于控制台的应用程序来列出所有这些项目，然后添加多个项目并显示价格

这是我尝试过的代码。我可以添加数字，但我不知道如何将用户的输入转换为变量

例如，当我运行控制台应用程序时，我希望用户输入他想要的汉堡数量。然后他选择了数字3

请温柔一点

import java.util.Scanner;
import java.util.*;
public class Test {
    public static void main(String[] args) {
        String file = "1,Cheese Burger,50;2,Pizza,70;3,Coke,20;4,Beer,20";
        //split
        String [] elements = file.split(";");
        //convert string to list of string
        List<String> fixedLengthList = Arrays.asList(elements);
        //copy fixed to arraylist
        ArrayList<String> listOfString = new ArrayList<String>(fixedLengthList);

       int  p = 0;
        while (p != 5) {
            Scanner sc = new Scanner(System.in);
            for (String line : listOfString
            ) {
                System.out.println("1. Cheese burger 50");
                System.out.println("2. Pizza 80");
                System.out.println("3. View your bill");
                sc.nextInt();
                String[] items = line.split(",");
                String itemPriceString = items[2];
                double itemPrice = Double.parseDouble(itemPriceString);
                double burger = itemPrice;
                System.out.println(burger+burger);

            }
        }

   }
}

也许这有助于：

Scanner sc = new Scanner(System.in);
while (true) {
    // print the menu
    for (String menuItem : listOfString) {
        String[] item = menuItem.split(",");
        System.out.println(item[0] + ". " + item[1] + " " + item[2]);
    }

    // read the selection
    int selection = sc.nextInt();
    if (selection == 3) {
        // print bill
        break;
    }

    // get information of selected item
    String[] selectedItem = listOfString.get(selection);
    String itemName = selectedItem[1];
    int itemPrice = Integer.parseInt(selectedItem[2]);
}

---

很抱歉，我不能完全理解这个问题，但我想推荐一些技巧来管理捆绑包中的类似变量

与C++中的数据结构（如对和TUPE）一样，java有一种声明“类”< /P>的方法

 class Menu {
int order;       //for food order number
 String name;    // for food name,
int price;       //for food price

Menu(String name, int price){
  //following the 'Constructor' We can put data
  this.name = name;
  this.price = price;
  }

}

那我们怎么用呢?

以这种方式使用列表

       String file = "1,Cheese Burger,50;2,Pizza,70;3,Coke,20;4,Beer,20";

    //split
    String [] elements = file.split(";");

    List<Menu> foodMenu = new ArrayList<Menu>();        //init

    for(int i = 0; i< 4; i++) { //4 foods
        String [] line = elements[i].split(",");

        foodMenu.add(new Menu(Integer.parseInt(line[0]), //food order number
                        line[1],                         //food name
                        Integer.parseInt(line[2]))       //food price
                );
    }
   /*foodMenu[0] = 1, Cheese Burger, 50
    foodMenu[1] = 2, Pizza, 70 
    foodMenu[2] = 3, Coke, 20
    foodMenu[3] = 4, Beer, 20

    if you want to access a data you can use like this
    foodMenu.get(index).order / name / price ; */

现在，让我们尝试一下这个新的存储系统，让客户选择购买和支付什么

import java.util.Scanner;
import java.util.*;

class Menu { 
    int order;      //for food order number
    String name;    // for food name
    int price;      //for food price

    Menu(int order, String name, int price){
        //following the 'Constructor' We can put data
        this.order = order;
        this.name = name;
        this.price = price;
    }

}


public class StackOver {
    public static void main(String[] args) {
        String file = "1,Cheese Burger,50;2,Pizza,70;3,Coke,20;4,Beer,20";

        //split
        String [] elements = file.split(";");

        List<Menu> foodMenu = new ArrayList<Menu>();        //init

        for(int i = 0; i< 4; i++) { //4 foods
            String [] line = elements[i].split(",");

            foodMenu.add(new Menu(Integer.parseInt(line[0]), //food order number
                            line[1],                         //food name
                            Integer.parseInt(line[2]))       //food price
                    );
        }
       //foodMenu[0] = 1, Cheese Burger, 50
      //foodMenu[1] = 2, Pizza, 70 
      //foodMenu[2] = 3, Coke, 20
      //foodMenu[3] = 4, Beer, 20

      //if you want to access a data you can use like this
      // foodMenu.get(index).order / name / price ;

   Scanner sc = new Scanner(System.in);


    int price = 0; //for purchase price
    int  p = 0; //Great Init for avoiding NullPointerException
    while (p != 5) {
            System.out.println("Please Input number 1 to 5 to Order food or purchase");
            System.out.println("1. Cheese burger 50$");
            System.out.println("2. Pizza 80$");
            System.out.println("3. Coke 20$");
            System.out.println("4. Beer 20$");
            System.out.println("5. Beer 20$");

            p = sc.nextInt();   //customer will choose number

            if(p!=5) {  
                price += foodMenu.get(p-1).price;
                //add price of selected food!
            }

        }
    System.out.println("Ok, The price is "+price+"$ in total");
    System.out.println("Have a nice day!");
    }
}

^示例结果

我希望这个答案能对你有所帮助，如果你不理解，请留下评论！

---

祝你有一个平静的一天

查看Scanner提供的其他方法，如next或nextLine。您可以将这些方法的返回值分配给字符串变量，如String line=sc.nextLine；我希望这对我很有帮助。非常感谢你的清楚解释。我会调整我的代码，我很高兴这个答案是有用的！！谢谢你的选择，希望你有一个和平的一天！