Java Learning Series - DB connection with Product Management System

Today, I created DBConnection class to connect database with Java application.

DBConnection.java

package com.company.db;

import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;

public class DBConnection{

    public static Connection getPSQLConnection(){
        Connection con = null;
        try{
            con = DriverManager.getConnection("jdbc:postgresql://localhost:5432/productdb", "postgres", "saravanan");
            System.out.println("SQL is connected");
        }
        catch(SQLException obj){
            System.out.println("SQL not connected");
        }
    return con;
    }
}

viewProduct() inside ProductService.java

    public void viewProduct() {
            try{
                Connection con = DBConnection.getPSQLConnection();
                String sql = "select * from products";
                PreparedStatement ps = con.prepareStatement(sql);
                System.out.println(ps);
                ResultSet rs = ps.executeQuery();
                System.out.println(rs);
                while(rs.next()){
                    System.out.println(rs.getInt("id"));
                    System.out.println(rs.getString("name"));
                    System.out.println(rs.getString("category"));
                    System.out.println(rs.getInt("price"));    
                }

            }catch(SQLException exe){
                System.out.println("SQLException");
            }
    }

Then, it has been called from Main.java

package com.company.controller;
import com.company.entity.Product;
import com.company.service.ProductService;

import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.FileNotFoundException;

public class Main{

    public static void main(String[] args) {

        ProductService service = new ProductService();

        service.viewProduct();
  }
}

Output:

SQL is connected
select * from products
org.postgresql.jdbc.PgResultSet@43195e57
1
chair
furniture
10000
2
mobile
electronics
20000

Comments

[Tyrian Trade]

Great share for beginners! Just a quick tip: remember to close your database connections (or use try-with-resources) to prevent connection leaks. Keep up the good work with this learning series!

[Saravanan Lakshmanan]

Thank you for your feedback! I'll make sure to close the database connections and explore try with resources in upcoming practice. Appreciate the tip and encouragement!