This file is used to "ISYS6197 Business Application Development" course in BINUS University Kemanggisan to teach about java application and MySQL database

DbHandler.java

/**
 * Author : Ivan F.E. (IV18-1)
 * This file is used to "ISYS6197 Business Application Development" course in BINUS University Kemanggisan 
 * to teach about java application and MySQL database
 * 2019
 */

package util;

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

import com.mysql.jdbc.Driver;

public class DbHandler
{
	/**
	 * Server Name 
	 */
	private final static String DB_SERVER = "localhost";
	
	/**
	 * Server Port
	 */
	private final static int DB_PORT = 3306;
	
	/**
	 * Database Name
	 */
	private final static String DB_NAME = "my_todo";
	
	/**
	 * Username for Current Selected Database
	 */
	private final static String DB_USERNAME = "root";
	
	/**
	 * Password for Current Selected Username
	 */
	private final static String DB_PASSWORD = "";
	
	/**
	 * Simple connection string to connect to MySQL database
	 */
	private static String connectionString = 
			String.format("jdbc:mysql://%s:%d/%s", 
					DB_SERVER, 
					DB_PORT, 
					DB_NAME);
	
	private static Connection conn;
	
	private DbHandler() {}
	
	/**
	 * Get connection from metadata that has been provided above.
	 * @return Opened connection.
	 */
	private static Connection getConnection()
	{
		if (conn == null)
		{
			try
			{
				DriverManager.registerDriver(new Driver());
				
				conn = (Connection) DriverManager.getConnection(connectionString, 
						DB_USERNAME, 
						DB_PASSWORD);
			}
			catch (SQLException e)
			{
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
		
		return conn;
	}

	/**
	 * Use to retrieve data from MySQL database.
	 * @param query SELECT Query
	 * @return Records in ResultSet Data Type
	 */
	public static ResultSet executeQuery(String query)
	{
		try (Statement stmt = getConnection().createStatement())
		{
			return stmt.executeQuery(query);
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
		
		return null;
	}
	
	/**
	 * Use to execute command for data manipulation in MySQL database.
	 * @param query INSERT, UPDATE, DELETE Query
	 */
	public static void execute(String query)
	{
		try (Statement stmt = getConnection().createStatement())
		{
			stmt.executeUpdate(query);
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}
	}
}