java - 如何在 Java 中将 Double 值分配给字符串数组列表？

Question

对于此代码，我创建了一个数组列表，其中提示用户将字符串类型的硬币输入到“钱包”中，然后将其添加到数组列表中。我有一个返回数组列表的方法，打印出列表中的硬币。我创建了其他几个方法，它们以多种方式作用于数组列表。我遇到的主要问题是创建一个名为 Coin 的类，在其中我想为数组列表“coins”中输入的每个硬币分配一个值。这将允许我创建一个方法来将“硬币”数组中每个硬币的值相加，或者创建一个从“硬币”数组中花费硬币的方法。我考虑过在 Coins 类中添加一个 public void setType(String Enter) 方法来为每个输入的硬币分配一个值，但我不完全确定如何去做。然而，一旦完成，我知道我想要创建一个列表:List coinPocket = new ArrayList<>();以及一个将 Coin 类中的值添加到数组列表的私有(private)方法:ArrayList coin = new ArrayList();。我想知道是否有人知道我会怎么做。这是到目前为止我的所有代码:

public class Coin 
{   
    private String type;
    private String currencyType;

    private double penny = 0.01;
    private double quarter = 0.25;
    private double dime = 0.10;
    private double nickle = 0.05;

    public void setType(String entered)
    {

    }
}

<小时/>

import java.util.ArrayList;
import java.util.Scanner;
import java.util.Collections;
import java.util.List;

/**
 * 
 * A class that contains methods and variables for adding and rearranging coins in a purse. An array list of coins; two variables, TERMINATE to stop adding coins and coinEntered to represent a coin in the purse; and a Scanner for user input are used.
 */
public class Purse 
{
    ArrayList<String> coins = new ArrayList<String>();
    List<Coin> coinPocket = new ArrayList<>();

    Scanner in = new Scanner(System.in);
    private final String TERMINATE = "Q";
    private String coinEntered = " ";

        private void addCoins(String coinType)
        {
            Coin cash = new Coin();
            cash.setType(coinType);
            coinPocket.add(cash);
        }

        /**
         * A method that allows the user to add coins to their purse and second purse, assuming it is American currency. If it is not American currency, the user is asked to enter the correct currency. The user will be prompted to press Q to quit adding coins once they have added them all.
         * @param coinName
         * 
         */
        public void addCoin(String coinName)
        {
            System.out.println("Which coin would you like to add? PENNY, NICKLE, DIME, or QUARTER? Press Q to stop adding coins.");

            while (!coinEntered.equals(TERMINATE))
            {
               coinEntered = in.nextLine();

               if (coinEntered.equals("PENNY") || coinEntered.equals("NICKLE") || coinEntered.equals("DIME") || coinEntered.equals("QUARTER") || coinEntered.equals(TERMINATE))
               {
                            coins.add(coinEntered);
                            coins.remove(TERMINATE);
               }
               else
               {
                System.out.println("Sorry! You can only add American currency to the purse. Please add American currency.");
               }
            }
        }

        /**
         * Prints out the purse and its contents after adding coins.
         * @return 
         * Purse with added coins.
         */
        public ArrayList<String> printPurseContents()
        {
            return coins; 
        }

        /**
         * Reverses the order of the coins in a purse, then prints out the contents of the purse in reverse order.
         * @return
         * Reverse order of array of coins.
         */
        public ArrayList<String> reverse()
        {
           Collections.reverse(coins);
           return coins;
        }

        /**
         * A method that allows the user to transfer coins in a purse to a different purse. The coins transfered from the original purse will leave that purse empty.
         * @param otherPurse
         * 
         */
        public void transfer(Purse otherPurse)
        {   
            coins.addAll(otherPurse.coins);
            otherPurse.coins.clear();
        }   

        /**
         * Method that checks whether one purse has the same coins in the same order as another purse.
         * @param otherPurse
         * @return Prints true if the contents of each purse have the same coins and the same order of coins, or false if the contents of each purse do not have the same coins and the same order of coins.
         */
        public boolean sameContents(Purse otherPurse)
        {
            if(otherPurse.coins.equals(coins))  
            {
                System.out.println("It is true that each purse has the same coins in the same order.");
                return true;
            }
            else
            {
                System.out.println("It is false that each purse has the same coins in the same order.");
                return false;
            }
        }

        /**
         * Method that checks whether one purse has the same coins as another purse regardless of the order of coins.
         * @param otherPurse
         * @return Prints true if each purse has the same coins as another purse regardless of order, or prints false if each purse does not have the same coins as another purse regardless of order.
         */
        public boolean sameCoins(Purse otherPurse)
        {
            if(otherPurse.coins.containsAll(coins))
            {
                System.out.println("It is true that each purse has the same coins regardless of order.");
                return true;
            }
            else
            {
                System.out.println("It is false that each purse has the same coins regardless of order.");
                return false;
            }
        }

        public void addTotalCoins()
        {

        }

        public void spendCoin()
        {

        }
}       

<小时/>

public class PurseMain 
{
    public static void main(String[] args) 
    {   
        Purse johnnysPurse = new Purse();
        Purse otherPurse = new Purse();

        johnnysPurse.addCoin(null);
        otherPurse.addCoin(null);

        System.out.println("Purse " + johnnysPurse.printPurseContents());
        System.out.println("Purse " + otherPurse.printPurseContents());

        System.out.println();

        System.out.println(otherPurse.sameContents(johnnysPurse));
        System.out.println();
        System.out.println(otherPurse.sameCoins(johnnysPurse));

        System.out.println();

    }
}

Answer 1

如果我正确理解你的问题，你想要求用户输入“PENNY”、“DIME”等字符串，并从中创建一个硬币。

为此，您可以使用带有属性的枚举，例如:

enum CoinType {
  PENNY(0.01),
  NICKLE(0.05)
  DIME(0.1),
  QUARTER(0.25);

  private final double value;

  private CoinType( double v ) {
    value = v;
  }

  public double getValue() {
    return value;
  }
}

然后询问用户一个号码(提供选择列表)或姓名。假设您询问姓名，则可以执行以下操作:

CoinType type = CoinType.valueOf( coinEntered );

捕获IllegalArgumentException以防用户输入错误的名称。