如何將數據庫值映射到對象數組？

Question

public C[] getC() throws SQLException, ClassNotFoundException { 
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); 
    String url = "jdbc:odbc:Mydb"; 
    String user = "user1"; 
    String password = "password"; 
    Connection con = DriverManager.getConnection(url,user,password); 
    Statement smt= con.createStatement(); 
    String query = "Select ssn, cname from customer"; 
    ResultSet rs = smt.executeQuery(query); 
    C [] c = new C[getNumberOfCustomers()]; 
    while (rs.next()){ 
     String ssn = rs.getString("ssn"); 
     String customer_name = rs.getString("cname"); 
    }  
    return custarray;  
} 

這裏是C的代碼：

public class C { 

    private String name; 
    private String SocialSecurityNumber; 

    public C(String name, String SocialSecurityNumber) { 
     this.name = name; 
     this.SocialSecurityNumber = SocialSecurityNumber; 
    } 

    public String getName() { return name; } 
    public void setName(String name) { this.name = name; } 
    public String getSocialSecurityNumber() { return SocialSecurityNumber; } 
    public void setSsn(String SocialSecurityNumber) { 
     this.SocialSecurityNumber = SocialSecurityNumber; 
    } 
} 

在這裏，我順便SSN和CUSTOMER_NAME到C[]陣列

Answer 1

C [] c = new C[getNumberOfCustomers()]; 
int i = 0; 
while (rs.next()){ 
    c[i++] = new C(rs.getString("cname"), rs.getString("ssn")); 
} 

FYI具有問題：甲List<C>will be better than an array of C，下面的代碼使用一個可重複使用的列表，new僅在target == null（例如第一次使用）時發生。

public List<C> getC(List<C> target) throws SQLException,ClassNotFoundException{ 
    if(target == null) { 
     target = new LinkedList<C>(); 
    } 
    else { 
     target.clear(); 
    } 
    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); 
    String url = "jdbc:odbc:Mydb"; 
    String user = "user1"; 
    String password = "password"; 
    Connection con = DriverManager.getConnection(url,user,password); 
    Statement smt= con.createStatement(); 
    String query = "Select ssn, cname from customer"; 
    ResultSet rs = smt.executeQuery(query); 
    while(rs.next()){ 
     target.add(new C(rs.getString("cname"), rs.getString("ssn"))); 
    } 
    return target; 
} 

Answer 2

你可以這樣做：

List<C> list = new ArrayList<C>(); 
while (rs.next()){ 
    String ssn = rs.getString("ssn"); 
    String customer_name = rs.getString("cname"); 
    C c = new C(ssn, customer_name); 
    list.add(c); 
} 
C[] lc = new C[list.size()]; 
list.toArray(lc);