cafeteriasurvey.java

32个java程序源代码

// Exercise 16.13: CafeteriaSurvey.java
// Program that asks 20 users to enter a rating of the quality of
// food in the student cafeteria and displays a bar graph of the
// data. User can add ratings between the values of 1 and 10, with
// 1 being "awful" and 10 being "excellent."
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class CafeteriaSurvey extends JFrame
{
   // JLabels for labeling x-axis bar graph
   private JLabel oneJLabel;
   private JLabel ratingsJLabel;
   private JLabel tenJLabel;

   // JLabel and JComboBox for choosing a rating
   private JLabel ratingJLabel;
   private JComboBox ratingJComboBox;

   // JButton to submit a rating
   private JButton submitRatingJButton;

   // JLabel and JTextArea for displaying all ratings
   private JLabel resultJLabel;
   private DrawJPanel drawingJPanel;

   // JLabels for labeling y-axis of bar graph
   private JLabel zeroJLabel;
   private JLabel resultsJLabel;
   private JLabel twentyJLabel;

   // String array to hold the user's choices
   private String[] choices = { "1", "2", "3", "4", "5", "6",
      "7", "8", "9", "10" };

   // integer array to track user responses
   private int[] responses = new int[ 11 ];

   private int responseCounter = 0; // tracks number of responses
   
   // no-argument constructor
   public CafeteriaSurvey()
   {
      createUserInterface();
   }

   // 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 oneJLabel
      oneJLabel = new JLabel();
      oneJLabel.setBounds( 50, 135, 25, 25 );
      oneJLabel.setText( "1" );
      contentPane.add( oneJLabel );

      // set up ratingsJLabel
      ratingsJLabel = new JLabel();
      ratingsJLabel.setBounds( 10, 245, 50, 25 );
      ratingsJLabel.setText( "Ratings" );
      contentPane.add( ratingsJLabel );

      // set up tenJLabel
      tenJLabel = new JLabel();
      tenJLabel.setBounds( 50, 370, 25, 25 );
      tenJLabel.setText( "10" );
      contentPane.add( tenJLabel );
      
      // set up ratingJLabel
      ratingJLabel = new JLabel();
      ratingJLabel.setBounds( 75, 20, 140, 20 );
      ratingJLabel.setText( "Rate cafeteria food:" );
      contentPane.add( ratingJLabel );

      // set up ratingJComboBox
      ratingJComboBox = new JComboBox( choices );
      ratingJComboBox.setBounds( 285, 20, 80, 25 );
      contentPane.add( ratingJComboBox );
      
      // set up submitJButton
      submitRatingJButton = new JButton();
      submitRatingJButton.setBounds( 135, 60, 130, 25 );
      submitRatingJButton.setText( "Submit Rating" );
      contentPane.add( submitRatingJButton );
      submitRatingJButton.addActionListener(
      
         new ActionListener() // anonymous inner class
         {
            // event handler called when
            // submitRatingJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               submitRatingJButtonActionPerformed( event );
            }
            
         } // end anonymous inner class
    
      ); // end call to addActionListener
      
      // set up resultJLabel
      resultJLabel = new JLabel();
      resultJLabel.setBounds( 75, 100, 100, 20 );
      resultJLabel.setText( "Survey results:" );
      contentPane.add( resultJLabel );
      
      // set up drawingJPanel
      drawingJPanel = new DrawJPanel();
      drawingJPanel.setBounds( 75, 135, 310, 255 );
      drawingJPanel.setBackground( Color.WHITE );
      contentPane.add( drawingJPanel );

      // set up zeroJLabel
      zeroJLabel = new JLabel();
      zeroJLabel.setBounds( 75, 390, 25, 25 );
      zeroJLabel.setText( "0" );
      contentPane.add( zeroJLabel );

      // set up resultsJLabel
      resultsJLabel = new JLabel();
      resultsJLabel.setBounds( 200, 405, 50, 25 );
      resultsJLabel.setText( "Results" );
      contentPane.add( resultsJLabel );

      // set up twentyJLabel
      twentyJLabel = new JLabel();
      twentyJLabel.setBounds( 370, 390, 25, 25 );
      twentyJLabel.setText( "20" );
      contentPane.add( twentyJLabel );
      
      // set properties of application's window
      setTitle( "Cafeteria Survey" ); // set title bar text
      setSize( 450, 475 );            // set window size
      setVisible( true );             // display window

   } // end method createUserInterface
   
   // submit response and display results
   private void submitRatingJButtonActionPerformed( 
      ActionEvent event )
   {
      responseCounter++; // increment counter

      // variable to hold user input
      int input = ratingJComboBox.getSelectedIndex() + 1;
      
      responses[ input ]++; // add user input to responses array

      // draw the bar graph
      drawingJPanel.drawGraph( responses );
      
      // if 20 ratings have been entered
      if ( responseCounter == 20 )
      {
         // disable the submitRatingsJButton
         submitRatingJButton.setEnabled( false );
      }

   } // end submitJButtonActionPerformed
   
   // main method
   public static void main( String args[] )
   {
      CafeteriaSurvey application = new CafeteriaSurvey();
      application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

   } // end method main
   
} // end class CafeteriaSurvey

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