java - 创建不确定数量的对象放入双端队列中

Question

我正在尝试创建一个用户定义的双端队列来存储用户定义的数量对象。我创建一个 item 对象并为其指定值或 item# 和价格，然后将该对象存储在双端队列中。到目前为止，我的 Main 由一个单一的项目组成。每次我设置该项目时，它都会用最新的值覆盖以前存储的项目值。我怎样才能创建无限数量的项目来存储它们？

主要

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

public class MyDequeApp {

public static void main(String[] args)
{
    //variables
    String userinNum;
    double userinPrice;
    int queOp;

    //creating new Item
    Item item1= new Item();

    //creating new Scanner      
    Scanner scan1=new Scanner(System.in);

    //user input number of elements in the deque
    System.out.println("Enter the number of elements in the que");
    int queElm=scan1.nextInt();     
    MyDeque theQueue=new MyDeque(queElm);

    //do/while so while user selects 1-7 they stay in the switch/case
    do
    {
        //switch/case menu
        System.out.println("1. Insert to front");
        System.out.println("2. Insert to rear");
        System.out.println("3. Remove from front");
        System.out.println("4. Remove from rear");
        System.out.println("5. Peek front");
        System.out.println("6. Peek rear");
        System.out.println("7. Display deque");
        System.out.println("Anything else to Quit");

        //user input the case number
        queOp=scan1.nextInt();
        scan1.nextLine();

        switch(queOp)
        {
            //insert to front
            case 1:
                System.out.println("Enter an item number");
                userinNum=scan1.nextLine();
                item1.setNum(userinNum);
                System.out.println("Enter a price");
                userinPrice=scan1.nextDouble();
                scan1.nextLine();
                item1.setPrice(userinPrice);
                System.out.println(item1.toString());
                theQueue.insertFront(item1);
                    break;

            //insert to rear
            case 2:
                System.out.println("Enter an item numbeR");
                userinNum=scan1.nextLine();
                item1.setNum(userinNum);
                System.out.println("Enter a pricE");
                userinPrice=scan1.nextDouble();
                scan1.nextLine();
                item1.setPrice(userinPrice);
                System.out.println(item1.toString());
                theQueue.insertFront(item1);
                theQueue.insertRear(item1);
                    break;

            //remove from front
            case 3:
                theQueue.removeFront();
                    break;

            //remove from rear
            case 4:
                theQueue.removeRear();
                    break;

            //peek front
            case 5:
                System.out.println(theQueue.peekFront());
                    break;

            //peek rear
            case 6:
                System.out.println(theQueue.peekRear());
                    break;

            //display the deque
            case 7: 
                System.out.println(theQueue.toString());
                    break;

            //quit
            default:
                    break;


        }

    }while(queOp>0 && queOp<8); 

}

}

Answer 1

您需要添加

item1= new Item(); 

要么在您完成一项并将其添加到队列中之后，要么在您为新一项输入数据之前的某个位置，否则程序会认为 item1 始终是同一项。