编辑：我还有另外两个类，称为CheckingAccount和SavingsAccount。我还要添加我的帐户代码。
我有一个Account类，正在研究另一个Ledger类，它与Account具有“ HAS-A”关系。在Ledger中，我使用HashMap <>（）为不同的帐户创建一个存储系统。我认为我的大多数编码都是正确的，期待最后两种方法。如果有人可以为后两种方法在正确的方向上进行解释或点头，然后再进行我的其他工作，那也会有所帮助。每个方法下面是该方法应该执行和返回的注释框。谢谢。
/**
* @author Deborah
*
*/
public abstract class Account {
protected String accountID;
protected double balance;
protected String accountType;
protected String firstName;
protected String lastName;
public String getAccountID() {
return this.accountID;
}
public double getBalance() {
return this.balance ;
}
public String getAccountType() {
return this.accountType;
}
public String getFirstName() {
return this.firstName;
}
public String getLastName() {
return this.lastName;
}
public void setAccountID(String accountID) {
this.accountID = accountID;
}
public void setBalance(double balance) {
this.balance = balance;
}
public void setAccountType(String accountType) {
this.accountType = accountType;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String toString() {
return "Account ID: " + accountID + "\n" +
"Account Type: " + accountType + "\n" +
"Balance: $" + balance + "\n";
}
public abstract IAccountManager getAccountManager();
}
public class Ledger {
//the single instance of Ledger
private static final Ledger instance = new Ledger();
//create accounts: Map<String, Account>
//use to add an Account, retrieve an Account, ect...
HashMap<String, Account> accounts = new HashMap<>();
//private constructor
private Ledger() {}
//method to return the single instance
public static Ledger getInstance(){
return instance;
}
public boolean store(Account account) {
/* adds a new Account to the accounts Map. The key is the account’s ID. This
* method should return a Boolean object that is "true" when the Account added
* to the ledger is being added for the first time, "false" if it is being
* updated. Check the documentation for the Map.put() method for reference.
*/
String key = account.getAccountID();
if(accounts.put(key, account) != null){
accounts.put(key, account);
return true;
}
return false;
}
public Account retrieve() {
/* returns a single Account with the specified accountID from the accounts Map.
* If none is found, return null.
*/
Account account = new Account();
String key = account.getAccountID();
if(accounts.containsKey(key)) {
return account;
}
return null;
}
public Account createAccount(Account account) {
/* this method creates and returns a new Account object with the specified
* parameters (type, firstName, lastName). Calling this method should store the
* new account within the accounts Map. Please note the first parameter passed
* into this method determines which account type (CheckingAccount vs.
* SavingsAccount) to create. The values should either be “checking” or
* “savings”.
*/
String key = account.getAccountType();
if(accounts.containsKey("Checking")) {
accounts.put(key,account);
return account;
}else{
accounts.put(key,account);
return account;
}
}
public Account getNextAccountID() {
/*this is a helper method that can be used to find out what the next
* accountID will be based on the number of Accounts within the accounts Map.
* It should return the size of the accounts Map plus one.
*/
return accounts.size() + 1;
}
public Ledger getAllAccounts() {
/*this method returns a list of all the Accounts w/in the accounts Map
*/
return null;
}
}
答案 0 :(得分：1)
注意：我将hashmap键更改为int，如果要使用String，则需要进行必要的更改
更改为商店帐户
您检查帐户是否已经存在的条件是错误的，不能为此使用put方法，而应使用containsKey
public boolean store(Account account) {
/* adds a new Account to the accounts Map. The key is the account’s ID. This
* method should return a Boolean object that is "true" when the Account added
* to the ledger is being added for the first time, "false" if it is being
* updated. Check the documentation for the Map.put() method for reference.
*/
int key = account.getAccountID();
if(accounts.containsKey(key) != null){
accounts.put(key, account);
return true;
}
return false;
}
对retrieve方法的更改：
此方法用于获取帐户，因此需要在此处创建一个新的account实例。明确规定，如果找不到帐户，请返回null。
从帐户映射中返回具有指定帐户ID的单个帐户。
这意味着方法应将accountId作为参数，然后我们需要在地图中进行搜索。
public Account retrieve(int accountId) {
/* returns a single Account with the specified accountID from the accounts Map.
* If none is found, return null.
*/
if(accounts.containsKey(accountId)) {
return accounts.get(accountId);
}
return null;
}
更改为createAccount：
1）传递规范中指定的参数（类型，名字和姓氏）
2）当我们从int方法返回一个int时，您的哈希映射键现在为getNextAccountID。这对我来说更有意义。
3）创建新帐户时需要从此函数调用getNextAccountID。
4）我假设您在SavingAccount和CheckingAccount类中具有构造函数。如果不这样做，请在默认构造函数初始化后创建一个或使用set方法。您的构造函数应将余额值分配为0。
public Account createAccount(String accountType, String firstName, String lastName) {
/* this method creates and returns a new Account object with the specified
* parameters (type, firstName, lastName). Calling this method should store the
* new account within the accounts Map. Please note the first parameter passed
* into this method determines which account type (CheckingAccount vs.
* SavingsAccount) to create. The values should either be “checking” or
* “savings”.
*/
int accountId = getNextAccountID();
Account acc;
if(type == "checking"){
acc = new CheckingAccount(id, type, firstName, lastName);
} else {
acc = new SavingAccount(id, type, firstName, lastName);
}
return acc;
}
更改为getNextAccountID：
1）返回一个整数（如果需要，可以将其更改为long）
public Integer getNextAccountID() {
/*this is a helper method that can be used to find out what the next
* accountID will be based on the number of Accounts within the accounts Map.
* It should return the size of the accounts Map plus one.
*/
return accounts.size() + 1;
}
答案 1 :(得分：0)
首先，此方法getNextAccountID应该返回一个整数
第二点，我建议
public List<Account> getAllAccounts() {
Set<Account> allaccounts = accounts.values();
LinkedList<Account> l ;
l.addAll(allacounts);
return l;
}
在我的建议中，我尝试使用界面映射中的methode值将帐户保存在一组中，然后将保存在该组中的所有帐户添加到列表中，最后返回该列表，我希望它将是有用。