java - BlueJ 如何从数组中获取数据以便与用户输入进行比较

Question

我目前正在摆弄 BlueJ，并尝试让对象之间进行交互。我已经创建了一个帐户和帐户列表类。帐户列表允许您添加帐户对象，然后将其放入数组列表中。

通过索引从数组中删除这些帐户很容易，使用 for 循环来获取每个帐户的位置，但现在它应该删除指定为参数的帐号的帐户，我不知道如何从数组中获取帐号，并将其与用户输入进行比较。

AccountList类

/**
 * Creates an AccountList that will store customers accounts
 * 
 * @author Ryan Conway
 * @version 12/11/2014
 */

import java.util.*;

public class AccountList
{

    private ArrayList < Account > accounts;

    /**
     * Create an AccountList that will contain accounts.
     */
    public AccountList()
    {

        accounts = new ArrayList < Account >();

    }

    /**
     * Add a account to this AccountList.
     */
    public void addAccount(Account newAccount)
    {
        accounts.add(newAccount);
    }

    /**
     * Return the number of accounts stored in this AccountList.
     */
    public int getNumberOfAccounts()
    {
        return accounts.size();
    }

    /**
     * prints out the number of accounts to the terminal.
     * for each loop used to get each account.
     */
    public void getAllAccounts()
    {
        for(Account account : accounts)
        {
            account.printAccountDetails();
        }

        System.out.println("Number of accounts: " + getNumberOfAccounts());
    }


    /**
     * Print out details of a account
     * @param accountEntry The entry in the list
     */
    public void getAccount(int accountEntry)
    {
        if(accountEntry < 0)
        {
            System.out.println("Negative entry :" + accountEntry);
        }
        else if(accountEntry < getNumberOfAccounts())
        {
            Account account = accounts.get(accountEntry);
            account.printAccountDetails();

        }
        else
        {
            System.out.println("No such entry :" + accountEntry);
        }
    }

    /**
     * removes a account from the list
     * @param accountEntry The entry in the list
     */
    public void removeAccount(int accountEntry)
    {
        if(accountEntry < 0)
        {
            System.out.println("Negative entry :" + accountEntry);
        }
        else if(accountEntry < getNumberOfAccounts())
        {
            accounts.remove(accountEntry);
        }
        else
        {
            System.out.println("No such entry :" + accountEntry);
        }
    }

    public boolean removeAccount(String accountNumber)
    {
        int index = 0;
        for(Account account : accounts)
        {
            if (accounts.equals(accountNumber))
                System.out.println("Found It!");
            index++;
        }
        return false;


    }


    public void printCollection()
    {
        System.out.println(accounts);
    }
}

帐户类别

/**
 * Write a description of class Account here.
 * 
 * @author (your name) 
 * @version (a version number or a date)
 */
public class Account
{
    private String firstName;
    private String lastName;
    private String accountNumber;
    private int pointsHeld;
    private Address address;

    /**
     * Constructor for objects of class Account.
     * The number of pointsHeld should be set to zero.
     * 
     * @param firstName The Account Holder's first name 
     * @param lastName The Account Holder's last name
     * @param accNumber The Account Holder's account number
     * @param street the account holder's street
     * @param town the account holder's town
     * @param postcode the account holder's postcode
     */
    public Account(String fName, String lName, String accNumber,
                   String street, String town, String postcode)
    {
        firstName = fName;
        lastName = lName;
        accountNumber = accNumber;
        pointsHeld = 0;       
        address = new Address(street, town, postcode);
    }

    /**
     * Constructor for objects of class Account.
     * The number of pointsHeld should should be set to
     * the supplied value.
     * 
     * @param fName The Account Holder's first name 
     * @param lName The Account Holder's last name
     * @param acctNumber The account number
     * @param thePoints the pointsHeld awarded when account is initialised
     * @param street the account holder's street
     * @param town the account holder's town
     * @param postcode the account holder's postcode
     */
    public Account(String fName, String lName, String acctNumber, int points,
                   String street, String town, String postcode)
    {
        firstName = fName;
        lastName = lName;
        accountNumber = acctNumber;
        pointsHeld = points;     
        address = new Address(street, town, postcode);
    }

    // accessors

    /**
     * Get the Account Holder's first name
     * 
     * @return the Account Holder's first name
     */
    public String getFirstName()
    {
        return firstName;
    }

    /**
     * Get the Account Holder's last name
     * 
     * @return the Account Holder's last name
     */
    public String getLastName()
    {
        return lastName;
    }

    /**
     * Get the Account Holder's account Number
     * 
     * @return the Account Holder's account number
     */
    public String getAccountNumber()
    {
        return accountNumber;
    }

     /**
     * Get the number of points held
     * 
     * @return the number of points held
     */
    public int getNoOfPoints()
    {
        return pointsHeld;
    }

    /**
     * Print out the Account Holder's details to the console window
     * 
     */
    public void printAccountDetails()
    {
        System.out.println( firstName + " " + lastName 
                           + "\n" + address.getFullAddress()
                           + "\nAccount Number: " + accountNumber
                           + "\nNumber of points: " + pointsHeld);
    }     

    /**
     * Return the account holder's address
     * 
     * @return the account holder's address
     */
    public String getAddress()
    {
        return address.getFullAddress();
    }

    // mutators     

    /**
     * Change the first name
     * 
     * @param fName the new first name
     * 
     */
    public void setFirstName(String fName)
    {
        firstName = fName;
    }

    /**
     * Change the last name
     * 
     * @param lName the new last name
     * 
     */
    public void setLastName(String lName)
    {
        lastName = lName;
    }

    /**
     * Increase the number of points held by a given number
     * and output a esage to the console window giving 
     * the revised number of points held.
     * 
     * @param number of points to add to total
     */
    public void addPoints(int points)
    {
        pointsHeld = pointsHeld + points;
        System.out.println("Points now held: " + pointsHeld);        
    }

    /**
     * Remove pointsHeld by a given number and output a 
     * message to the console window giving the revised number 
     * of points held as long as the number of points would 
     * not fall below zero
     * - otherwise output message to console window instead.
     * 
     * @param number of pointsHeld to remove total.
     * 
     */
    public void removePoints (int points)
    {
        if ((pointsHeld - points) >=0)
        {
            pointsHeld = pointsHeld - points;
            System.out.println("Points now held: " + pointsHeld);        
        }
        else
        {
            System.out.println("Transaction refused: "
                     + "Insufficient points available.");
        }
    }

    /**
     *  Change the account holder's address
     *  
     *  @param street the street
     *  @param town the town
     *  @postcode the postcode
     */
    public void setAddress(String street, String town, String postcode)
    {
        address.setFullAddress(street, town, postcode);
    }

    /** 
     * Print the account holder's address
     */
     public void printAddress()
     {
         address.printAddress();
     }    
} // end class

/image/FpsxJ.jpg

谢谢。

Answer 1

试试这个:

public boolean removeAccount(String accountNumber)
{
    Iterator<Account> iterator = accounts.iterator();

    while (iterator.hasNext()) 
    {
         if (accountNumber.equals(iterator.next().getAccountNumber()))
         {
            System.out.println("Found It!");
            iterator.remove();
            return true;
         }
    }

    return false;
}

在循环访问列表时从列表中删除项目并不是一个安全的操作，但 Iterator 类使这成为可能。更多信息:Iterating through a Collection, avoiding ConcurrentModificationException when removing in loop