DB.java

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

public class DB {
  private static String driver = "org.apache.derby.jdbc.EmbeddedDriver";

  private static String protocol = "jdbc:derby:memory";

  private static String dbPath = "/";

  private static String url = protocol + dbPath + "MemDB;create=true;";
  
  private static Statement stmt = null;

  private static Connection conn = null;

  private static String table = "MemTable";

  protected static void createConnection () {
    try {
      Class.forName(driver).newInstance();
      // Get a connection
      conn = DriverManager.getConnection(url);
    } catch (Exception except) {
      except.printStackTrace();
    }
  }

  protected static void createTable () {
    try {
      stmt = conn.createStatement();

      // Lets get rid of an existing table, if any, OW if the table exist already we get exception
      stmt.execute("drop table " + table);

      // We create a table...
      stmt.execute("create table " + table + "(num int, addr varchar(40))");
    } catch (SQLException e) {

      try {
        stmt.execute("create table " + table + "(num int, addr varchar(40))");
        return;
      } catch (SQLException e1) {
        e1.printStackTrace();
      }
      e.printStackTrace();
    }
  }

  protected static void insertAddress (int number, String street) {
    try {
      stmt = conn.createStatement();
      stmt.execute("insert into " + table + " values (" + number + ",'" + street + "')");
      stmt.close();
    } catch (SQLException sqlExcept) {
      sqlExcept.printStackTrace();
    }
  }

  protected static void shutdown () {
    try {
      if (stmt != null) {
        stmt.close();
      }
      if (conn != null) {
        DriverManager.getConnection(url + ";shutdown=true");
        conn.close();
      }
    } catch (SQLException sqlExcept) {

    }
  }
}