将数据从数据库添加到散列表 [英] adding data to hashmap from database

问题描述

你好，我正在创建一个应用程序，我可以将数据存储在购物车模块的Hashmap和List中。但我想从我的MS-Access数据库中获取这些数据。我尝试了下面的代码，但它没有编译。请给我指导。

代码：

  import java.sql。 *; 
 import java.util.ArrayList; 
 import java.util.HashMap; 
 import java.util.List; 
 
 public class Program {
 public static void main（String [] args）{} 
 $ b $ public static HashMap getProductsAsMap（）{
 try {
 Class.forName（sun.jdbc.odbc.JdbcOdbcDriver）; 
 Connection con = DriverManager.getConnection（jdbc：odbc：pd）; 
 ResultSet rs = null; 
 Statement st = con.createStatement（）; 
 String sql =（select * from products）; 
 rs = st.executeQuery（sql）; 
 while（rs.next（））{
 HashMap< String，ProductBean> products = new HashMap< String，ProductBean>（）; 
 String name = rs.getString（pname）; 
 String desc = rs.getString（pdesc）; 
 String image = rs.getString（pimage）; 
 products.put（P1，new ProductBean（name，desc，image））; 
退货产品; 
} 
 rs.close（）; 
 st.close（）; 
 con.close（）; 
} 
 catch（Exception e）{} 
} 
 
 public static List getProductsAsList（）{
 List< ProductBean> products = new ArrayList< ProductBean>（）; 
尝试{
 Class.forName（sun.jdbc.odbc.JdbcOdbcDriver）; 
 Connection con = DriverManager.getConnection（jdbc：odbc：pd）; 
 ResultSet rs = null; 
 Statement st = con.createStatement（）; 
 String sql =（select * from products）; 
 rs = st.executeQuery（sql）; 
 while（rs.next（））{
 String name = rs.getString（pname）; 
 String desc = rs.getString（pdesc）; 
 String image = rs.getString（pimage）; 
 products.add（new ProductBean（name，desc，image））; 
} 
 rs.close（）; 
 st.close（）; 
 con.close（）; 
} 
 catch（Exception e）{} 
返回产品; 
 
 
  

我得到2个错误，如下所示：

<您的 ProductBean 类没有一个构造函数，它将三个字符串作为参数。

Hello I am creating an application where I can store data in a Hashmap and List for a shopping cart module.But I want to fetch this data from my MS-Access database.I tried the following code but its not compiling.Please give me guidance.

Code:

import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class Program {
    public static void main(String [] args){}

    public static HashMap getProductsAsMap() {
        try {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection con = DriverManager.getConnection("jdbc:odbc:pd");
            ResultSet rs = null;
            Statement st = con.createStatement();
            String sql = ("select * from products");
            rs=st.executeQuery(sql);
            while (rs.next()) { 
                HashMap<String, ProductBean> products= new HashMap<String, ProductBean>();
                String name=rs.getString("pname");
                String desc=rs.getString("pdesc");
                String image=rs.getString("pimage");
                products.put("P1", new ProductBean(name,desc,image));
                return products;
            }
            rs.close();
            st.close();
            con.close();
        }
        catch(Exception e){}   
    }

    public static List getProductsAsList() {
        List<ProductBean> products = new ArrayList<ProductBean>();
        try {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            Connection con = DriverManager.getConnection("jdbc:odbc:pd");
            ResultSet rs = null;
            Statement st = con.createStatement();
            String sql = ("select * from products");
            rs=st.executeQuery(sql);
            while (rs.next()) { 
                String name=rs.getString("pname");
                String desc=rs.getString("pdesc");
                String image=rs.getString("pimage");
                products.add(new ProductBean(name,desc,image));
            }
            rs.close();
            st.close();
            con.close();
        }
        catch(Exception e){}
        return products;  
    }
}

I get 2 errors as follows:

解决方案

Your ProductBean class does not have a constructor that takes three strings as parameters.

这篇关于将数据从数据库添加到散列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！