这里我为帐户数据库构建了两个类： http://puu.sh/hiYKZ/01e0da1578.png
对于帐户列表，我收到错误：
错误6找不到类型或命名空间名称“连接” （您是否缺少using指令或程序集引用？）
public Connection acctsConnect(){
try{
Class.forName("C:\\ChattBankMDB.mdb");
}catch(ClassNotFoundException e){
Console.WriteLine("Error: " + e);
}
Connection connect = null;
try{
connect = DriverManager.getConnection("C:\\ChattBankMDB.mdb");
}catch(SQLException e){
Console.WriteLine("Error: " + e);
}
return connect;
}
}
}
帐户列表：
class AccountList
{
private static List<Accounts> custAccounts = new List();
private String userID = "";
public AccountList(){
}
public AccountList(String userID){
this.userID = userID;
}
public void setUserID(String userID){
this.userID = userID;
}
public String getUserID(){
return this.userID;
}
public void setCustAccounts(String custId) {
Connection connect = acctsConnect();
Statement statement = null;
ResultSet result = null;
String sql = "SELECT acctNo FROM Accounts Where Cid = '" + custId + "';";
try{
statement = connect.createStatement();
result = statement.executeQuery(sql);
while (result.next()){
result.getRow();
Account acct = new Account(result.getString("acctNo"));
custAccounts.add(acct);
}
}
finally {
connect.close();
}
}
public List<Accounts> getCustAccounts (){
return custAccounts;
}
public void clearAccounts(){
this.custAccounts.clear();
}
public Connection acctsConnect(){
try{
Class.forName("C:\\ChattBankMDB.mdb");
}catch(ClassNotFoundException e){
Console.WriteLine("Error: " + e);
}
Connection connect = null;
try{
connect = DriverManager.getConnection("C:\\ChattBankMDB.mdb");
}catch(SQLException e){
Console.WriteLine("Error: " + e);
}
return connect;
}
}
}
帐户：
class Accounts
{
private String acctNo;
private String custId;
private String type;
private double balance;
private String message;
/**
* No-Arg Constructor
*/
/**
*sets account number
*@param acctNo
*/
public void setAcctNo(String acctNo) {
this.acctNo = acctNo;
}
/**
*sets customer id
* @param custId
*/
public void setCustId(String custId) {
this.custId = custId;
}
/**
* sets account type
* @param acctType
*/
public void SetType(String type) {
this.type = type;
}
/**
* sets balance for the account
* @param balance
*/
public void setBalance(double balance) {
this.balance = balance;
}
/**
* returns account number
* @return String
*/
public String getAcctNo() {
return acctNo;
}
/**
* returns customer id
* @return String
*/
public String getCustId() {
return custId;
}
/**
* returns account type
* @return String
*/
public String getType() {
return type;
}
/**
* returns account balance
* @return double
*/
public double getBalance() {
return balance;
}
/**
* returns account information into string form
* @return String
*/
public String getAcct() {
return this.acctNo + " " + this.custId + " " + this.type + " " + this.balance;
}
/**
* returns message set by other methods in class
* @return String
*/
public String getMessage(){
return this.message;
}
public void deposit(String acctNo, double depAmount) {
Connection connect = acctConnect();
Statement statement = connect.createStatement();
ResultSet result = null;
String sql = "Select balance From Accounts Where acctNO = '" + acctNo + "';";
String update = null;
int updateSet = 0;
double balance = 0.00;
double newBalance;
result = statement.executeQuery(sql);
/* retrieves the balance of the current account */
while (result.next()) {
balance = result.getDouble("Balance");
}
/* updates the balance in this object and the database */
newBalance = balance + depAmount;
update = "Update Accounts Set Balance = '" + newBalance + "' Where acctNO = '" + acctNo + "';";
updateSet = statement.executeUpdate(update);
this.balance = newBalance;
/* closes connection */
connect.close();
}
public void withdraw(String acctNo, double withdrawal) {
Connection connect = acctConnect();
Statement statement = connect.createStatement();
ResultSet result = null;
String sql = "Select balance From Accounts Where acctNO = '" + acctNo + "';";
String update = null;
int updateSet = 0;
double balance = 0.00;
double newBalance;
result = statement.executeQuery(sql);
/* gets balance of the current account from the database */
while (result.next()) {
balance = result.getDouble("Balance");
}
/* checks to see if the withdrawal amount is more than the balance
and if so the exception is thrown and an insufficient funds message is
set */
if (balance < withdrawal){
this.message = "Insufficcient Funds";
throw new Exception();
}else{
/* sets new balance and updates the current database account balance */
newBalance = balance - withdrawal;
update = "Update Accounts Set Balance = '" + newBalance + "' Where acctNo = '" + acctNo + "';";
updateSet = statement.executeUpdate(update);
this.balance = newBalance;
}
/* closes connection to database */
connect.close();
}
public void transfer(String fromAcct, String toAcct, double transfer) {
/* Call withdraw method on from account */
withdraw(fromAcct, transfer);
/* deposit to to account */
deposit(toAcct, transfer);
/* both methods close their own database connection so it is not necessary to do so here */
}
/**
* Sets up new account for existing customers
* @param acctNo
* @param custID
* @param type
* @param balance
* @throws SQLException
*/
public void estabAccount(String custID, String type, double balance) {
Console.WriteLine(custID + " " + type + " " + balance);
/* Establish connection and update the database with a new row containing the new account info */
Connection connect = acctConnect();
Statement statement = connect.createStatement();
String sql = "Insert Into accounts (Cid, Type, Balance) Values ('" + custID + "', '" + type + "', " + balance + ");";
Console.WriteLine(sql);
/* Execute Query and close connection */
statement.executeUpdate(sql);
connect.close();
}
}
}
答案 0 :(得分：0)
您的班级名称是“帐户”，您正在制作“帐户”列表。将您的arraylists更改为通用List＆lt;＆gt ;.对于Connection，检查哪个命名空间定义了类，并将其放入，即导入该命名空间。
using namespace_where_Connection_is位于上方代码的顶部。
ArrayList<Account> custAccounts = new ArrayList();
更改为
List<Accounts> custAccounts = new List<Accounts>();