AirportChoice. java

AirportChoice.java class queries the database to build a list of airport codes such as SFO, LAX, or JFK. The list is used within the user interface to let the user choose the departure and arrival airports. Listing 10-6 shows the source code for AirPortChoice.java.

Listing 10-6: AirportChoice.java.

//
// AirportChoice.java - user interface widget showing a choice of airports
//
// Copyright (C) 1996 by Connect Software. All rights reserved.
//
// Written by Gionata Mettifogo, Peter Ham.
//
package airplet;
import connect.sql.*; // import jdbc and other sql libraries
import java.awt.*; // java windowing toolkit
/** A choice user interface widget showing a list of available airport codes. */
class AirportChoice extends Choice
{
  /**
  * Initialize the choice user interface widget with a list of airports
  * available in the database. The method will query the airports table
  * of the database, listing all available airports by code.
  */
  public AirportChoice() throws SQLException
  {
      // use sql to select all airport codes from the airports table then add them to the
        widget
      Statement s = Airplet.createStatement(); // scan all the airports in the table
      for(ResultSet r = s.executeQuery("select code from airports order by code") ; r.next()
        ;)
      {
           String name = r.getString(1); // name of this airport
           // System.out.println("AirportChoice - " + r.getString("code") + " is '" +
             name + "'");
           addItem(name); // add airport to the choices
      }
      s.close(); // close statement
  }
  /** Returns the Airport corresponding to the entry with the given index. */
  public Airport getAirport(int index)
  {
      return Airport.getAirport(getItem(index)); // return Airport object
               }
               /** Returns the currently selected Airport. */
               public Airport getSelectedAirport()
               {
      return getAirport(getSelectedIndex());
  }
}

ColumnLayout. java

ColumnLayout.java class arranges a set of components in a single column. The source code for this class is in Listing 10-7.

Listing 10-7: ColumnLayout.java.

//
// ColumnLayout.java - layout that arranges all components in a column
//
// Copyright (C) 1996 by Connect Software. All rights reserved.
//
// Written by Gionata Mettifogo.
//
package airplet;
import java.awt.*; // import java windowing classes
/** A layout that arranges all components in a single column. */
public class ColumnLayout implements LayoutManager // just another layout manager
{
  public ColumnLayout()
  {
      hgap = vgap = 0; // no gap between components
  }
  public ColumnLayout(int hgap,int vgap)
  {
      this.hgap = hgap; this.vgap = vgap; // use this spacing between components
  }
  private int hgap, vgap; // horizontal and vertical spacing between components
  /** Arrange components contained in iParent in a single column using their preferred size.
    */
  public void layoutContainer(Container iParent)
  {
      Insets insets = iParent.insets(); // insets (borders around the container)
      Dimension dimension = iParent.size(); // size of parent container
      dimension.width -= insets.left + insets.right; // net width of container
      for(int i = 0, v = vgap ; i < iParent.countComponents() ; i++)
      {
           Component component = iParent.getComponent(i); // scan each
             component in the container
           Dimension size = component.preferredSize(); // get component's
             preferred size the reshape it
           component.reshape(insets.left,v,dimension.width - insets.left -
             insets.right,size.height);
           component.repaint(); // redraw the component
           v += size.height + vgap; // update vertical origin for next component
      }
  }
  /** Returns the minimum layout size calculated using each component's preferred size. */
  public Dimension minimumLayoutSize(Container iParent)
  {
      Dimension dimension = new Dimension(0,0);
      for(int i = 0 ; i < iParent.countComponents() ; i++) // scan components
      {
      Component component = iParent.getComponent(i);
      Dimension size = component.preferredSize(); // get i-th component's size
      dimension.width = Math.max(dimension.width,size.width);
      dimension.height += size.height + vgap; // update height including this
        component
      }
      Insets insets = iParent.insets(); // add insets (border)
      dimension.width += insets.left + insets.right + 2 * hgap;
      dimension.height += insets.top + insets.bottom + vgap;
      return dimension;
  }
  /** Preferred size is just like minimum size but can be as wide as the parent component. */
  public Dimension preferredLayoutSize(Container iParent)
  {
      Dimension dimension = minimumLayoutSize(iParent);
      dimension.width = Math.max(iParent.size().width,dimension. width);
      return dimension;
  }
  public void addLayoutComponent(String iName,Component iComponent)
  {
  }
  public void removeLayoutComponent(Component iComponent)
  {
  }
}

Flight.java

Flight.java contains a constructor that initializes the members of the flight information and passes them as a parameter. It extracts the flight number, departure and arrival, flight frequency, and plane identification. Listing 10-8 shows the source code for this class.

Listing 10-8: Flight.java.

//
// Flight.java - holds information regarding a flight
//
// Copyright (C) 1996 by Connect Software. All rights reserved.
//
// Written by Gionata Mettifogo, Peter Ham.
//
package airplet;
import connect.sql.*;       // import jdbc and other sql libraries
class Flight
{
  /**
  * Initialize flight from the information contained in the current
  * row of this result set. The result set is a subset of rows from
  * the flights table in the airline database. This method will read
  * information on current row (it will not call next).
  *
  * @param iFlight is a result set whose current row is a flight
  */
  public Flight(ResultSet iFlight) throws SQLException
  {
      code = iFlight.getString("code"); // get flight number
      from = iFlight.getString("from_city"); to = iFlight.getString("to_city");
      departure = iFlight.getTime("departure"); arrival = iFlight.getTime("arrival");
      frequency = iFlight.getString("frequency"); // flight frequency (eg. which days this
        flight operates)
      plane = iFlight.getString("plane"); // airplane used
  }
  String code, from, to; // the flight code/number and city of departure/arrival, e.g.,
    'TWA800'
  Time departure, arrival; // departure and arrival time
  String frequency; // days when the flight is available, e.g., 123 for Mon, Tue, Wed
  String plane; // airplane used, e.g., "Boeing 767"
  public String toString()
  {
      return "Flight[" + code + "," + from + " " + departure + "," + to + " " + arrival + ","
        + frequency + "," + plane + "]";
  }
}