ticketinformation.java

来自「32个java程序源代码」· Java 代码 · 共 293 行

// Tutorial 25: TicketInformation.java
// This application reads information about events on different dates
// from a file created by class WriteEvent.
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.text.*;
import java.util.Date;
import javax.swing.*;
import javax.swing.event.*;

public class TicketInformation extends JFrame
{
   // JLabel and JSpinner to display date
   private JLabel dateJLabel;
   private JSpinner dateJSpinner;

   // JLabel and JComboBox to display day's events
   private JLabel eventJLabel;
   private JComboBox eventJComboBox;

   // JLabel and JTextArea to display details of events
   private JLabel descriptionJLabel;
   private JTextArea descriptionJTextArea;

   // BufferedReader to read data from a file
   private BufferedReader input;

   // File selected by user 
   private File calendarFile;

   // instance variables to store event information and number
   private String[][] daysEvents = new String[ 10 ][ 5 ];
   private int eventNumber;
   
   // no-argument constructor
   public TicketInformation()
   {
      createUserInterface();

      createEventList(); // read file and display events on given day
   }

   // create and position GUI components; register event handlers
   private void createUserInterface()
   {
      // get content pane for attaching GUI components
      Container contentPane = getContentPane();
      
      // enable explicit positioning of GUI components
      contentPane.setLayout( null );
      
      // set up dateJLabel
      dateJLabel = new JLabel();
      dateJLabel.setBounds( 16, 16, 121, 23 );
      dateJLabel.setText( "Select the day (1-31):" );
      contentPane.add( dateJLabel );

      // set up dateJSpinner
      dateJSpinner = new JSpinner( 
         new SpinnerNumberModel( 1, 1, 31, 1 ) );
      dateJSpinner.setBounds( 147, 16, 119, 23 );
      contentPane.add( dateJSpinner );
      dateJSpinner.addChangeListener(
      
         new ChangeListener() // anonymous inner class
         {
            // event handler called when dateJSpinner is changed
            public void stateChanged( ChangeEvent event )
            {
               dateJSpinnerStateChanged( event );
            }
            
         } // end anonymous inner class
         
      ); // end call to addActionListener            
            
      // set up eventJLabel
      eventJLabel = new JLabel();
      eventJLabel.setBounds( 16, 67, 100, 23 );
      eventJLabel.setText( "Pick an event: " );
      contentPane.add( eventJLabel );
      
      // set up eventJComboBox
      eventJComboBox = new JComboBox();
      eventJComboBox.setBounds( 16, 94, 250, 23 );
      eventJComboBox.addItem( "- No Events -" );
      contentPane.add( eventJComboBox );
      eventJComboBox.addActionListener(
      
         new ActionListener() // anonymous inner class
         {
            // event handler called when eventJComboBox is changed
            public void actionPerformed( ActionEvent event )
            {
               eventJComboBoxActionPerformed( event );
            }
            
         } // end anonymous inner class
         
      ); // end call to addActionListener            
            
      // set up descriptionJLabel
      descriptionJLabel = new JLabel();
      descriptionJLabel.setBounds( 16, 141, 100, 23 );
      descriptionJLabel.setText( "Description: " );
      contentPane.add( descriptionJLabel );
      
      // set up descriptionJTextArea
      descriptionJTextArea = new JTextArea();
      descriptionJTextArea.setBounds( 16, 168, 250, 125 );
      descriptionJTextArea.setText( "No events today." );
      descriptionJTextArea.setLineWrap( true );
      descriptionJTextArea.setWrapStyleWord( true );
      descriptionJTextArea.setEditable( false );
      contentPane.add( descriptionJTextArea );         
      
      // set properties of application's window
      setTitle( "Ticket Information" ); // set title bar string
      setSize( 292, 340 );              // set window size
      setVisible( true );               // display window

   } // end method createUserInterface
   
   // read event information from a file for a given date
   private void dateJSpinnerStateChanged( ChangeEvent event )
   {
      createEventList();
     
   } // end method dateJSpinnerStateChanged

   // display event information
   private void eventJComboBoxActionPerformed( ActionEvent event )
   {
      int selectedEvent = eventJComboBox.getSelectedIndex();
      descriptionJTextArea.setText( 
         daysEvents[ selectedEvent ][ 1 ] + "\n" +  // time 
         daysEvents[ selectedEvent ][ 2 ] + "\n" +  // price
         daysEvents[ selectedEvent ][ 4 ] );        // description

   } // end method eventJComboBoxActionPerformed

   // read events for current day and display events in application
   private void createEventList()
   {
      // get data from file
      extractData();
      
      // remove all information from last date
      eventJComboBox.removeAllItems();
      descriptionJTextArea.setText( "" );
      
      // if there are events scheduled for the current day
      if ( eventNumber > 0 )
      {
         // add events to the eventJComboBox
         for ( int x = 0; x < eventNumber; x++ )
         {
            eventJComboBox.addItem( daysEvents[ x ][ 3 ] );
         }
      }
      else // no events for the day
      {
         eventJComboBox.addItem( "- No Events -" );
         descriptionJTextArea.setText( "No events today." );
      }

   } // end method createEventList
   
   // read data from file
   private void extractData()
   {
      eventNumber = 0;

      // get date from dateJSpinner and format
      Integer date = ( Integer ) dateJSpinner.getValue();
      String currentDate = String.valueOf( date );

      // initialize daysEvents array
      initialize();
       
      // find and display events for current date
      try
      {
         // get file
         calendarFile = new File( "calendar.txt" );

         // open file
         FileReader currentFile = new FileReader( calendarFile );
         input = new BufferedReader( currentFile );

         // read a line from the file
         String contents = input.readLine();

         // while more lines are in the file
         while ( contents != null ) 
         {
            // if day selected is equal to the day read from the file
            if ( contents.equals( currentDate ) )
            {
               // read event information
               daysEvents[ eventNumber ][ 0 ] = contents;
               daysEvents[ eventNumber ][ 1 ] = input.readLine();
               daysEvents[ eventNumber ][ 2 ] = input.readLine();
               daysEvents[ eventNumber ][ 3 ] = input.readLine();
               daysEvents[ eventNumber ][ 4 ] = input.readLine();
               eventNumber++;
            }
            else // if date was not equal 
            {
               // move to next date in file
               for ( int x = 0; x < 4; x++ )
               {
                  input.readLine();
               }
            }
           
            // read a line from the file
            contents = input.readLine();
           
         } // end while
      }      
      catch ( IOException exception )
      {
         JOptionPane.showMessageDialog( this, 
            "Please make sure the file exists and is of the " +
            "right format.", "I/O Error", 
            JOptionPane.ERROR_MESSAGE );

         // disable components
         eventJComboBox.setEnabled( false );
         dateJSpinner.setEnabled( false );
      } 
      finally // close the file
      {
         // close the file
         try
         {
            input.close();
         } 
         catch( IOException exception )
         {
            JOptionPane.showMessageDialog( this, 
               "Please make sure the file exists and is of the " +
               "right format.", "I/O Error", 
               JOptionPane.ERROR_MESSAGE );
         }  
      }
             
   } // end method extractData
   
   // initialize daysEvents array
   private void initialize()
   {
      // for each of ten possible events per day
      for ( int i = 0; i <= 9; i++ )
      {
         // for each of five fields per event
         for ( int j = 0; j <= 4; j++ )
         {
            daysEvents[ i ][ j ] = "";
         }
      }
       
      daysEvents[ 0 ][ 3 ] = "- No Events -";
      daysEvents[ 0 ][ 4 ] = "No events today.";
   
   } // end method initialize 
   
   // main method
   public static void main( String[] args )
   {
      TicketInformation application = new TicketInformation();
      application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

   } // end method main

} // end class TicketInformation

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