cashregister.java

来自「32个java程序源代码」· Java 代码 · 共 549 行 · 第 1/2 页

// Exercise: 11.16 CashRegister.java
// Application simulates the behavior of a cash register, allowing
// the user to input prices, keep a running subtotal, and
// calculate the sales tax and total.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;

public class CashRegister extends JFrame
{
   double subtotal = 0.0; // stores subtotal of items purchased

   // JLabel and JTextField to enter amount
   private JLabel amountJLabel;
   private JTextField amountJTextField;

   // JButtons to enter numbers in amountJTextField
   private JButton oneJButton;
   private JButton twoJButton;
   private JButton threeJButton;
   private JButton fourJButton;
   private JButton fiveJButton;
   private JButton sixJButton;
   private JButton sevenJButton;
   private JButton eightJButton;
   private JButton nineJButton;
   private JButton zeroJButton;
   private JButton pointJButton;

   // JButton to add value in amountJTextField to subtotal
   private JButton enterJButton;

   // JButton to determine tax and calculate final total
   private JButton totalJButton;

   // JButton to delete value displayed in amountJTextField
   private JButton deleteJButton;

   // JButton to clear results
   private JButton clearJButton;

   // JLabel and JTextField to display subtotal
   private JLabel subtotalJLabel;
   private JTextField subtotalJTextField;

   // JLabel and JTextField to display tax
   private JLabel taxJLabel;
   private JTextField taxJTextField;

   // JLabel and JTextField to display final total
   private JLabel totalJLabel;
   private JTextField totalJTextField;

   // DecimalFormat to format dollar amounts
   private DecimalFormat dollars = new DecimalFormat( "$0.00" );

   // no-argument constructor
   public CashRegister()
   {
      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 amountJLabel
      amountJLabel = new JLabel();
      amountJLabel.setBounds( 20, 20, 15, 20 );
      amountJLabel.setText( "$" );
      contentPane.add( amountJLabel );

      // set up amountJTextField
      amountJTextField = new JTextField();
      amountJTextField.setBounds( 40, 20, 260, 20 );
      contentPane.add( amountJTextField );
      
      // set up oneJButton
      oneJButton = new JButton();
      oneJButton.setBounds( 55, 70, 45, 20 );
      oneJButton.setText( "1" );
      contentPane.add( oneJButton );
      oneJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when oneJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               oneJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up twoJButton
      twoJButton = new JButton();
      twoJButton.setBounds( 100, 70, 45, 20 );
      twoJButton.setText( "2" );
      contentPane.add( twoJButton );
      twoJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when twoJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               twoJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up threeJButton
      threeJButton = new JButton();
      threeJButton.setBounds( 145, 70, 45, 20 );
      threeJButton.setText( "3" );
      contentPane.add( threeJButton );
      threeJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when threeJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               threeJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up fourJButton
      fourJButton = new JButton();
      fourJButton.setBounds( 55, 90, 45, 20 );
      fourJButton.setText( "4" );
      contentPane.add( fourJButton );
      fourJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when fourJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               fourJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up fiveJButton
      fiveJButton = new JButton();
      fiveJButton.setBounds( 100, 90, 45, 20 );
      fiveJButton.setText( "5" );
      contentPane.add( fiveJButton );
      fiveJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when fiveJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               fiveJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up sixJButton
      sixJButton = new JButton();
      sixJButton.setBounds( 145, 90, 45, 20 );
      sixJButton.setText( "6" );
      contentPane.add( sixJButton );
      sixJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when sixJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               sixJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up sevenJButton
      sevenJButton = new JButton();
      sevenJButton.setBounds( 55, 110, 45, 20 );
      sevenJButton.setText( "7" );
      contentPane.add( sevenJButton );
      sevenJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when sevenJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               sevenJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up eightJButton
      eightJButton = new JButton();
      eightJButton.setBounds( 100, 110, 45, 20 );
      eightJButton.setText( "8" );
      contentPane.add( eightJButton );
      eightJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when eightJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               eightJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up nineJButton
      nineJButton = new JButton();
      nineJButton.setBounds( 145, 110, 45, 20 );
      nineJButton.setText( "9" );
      contentPane.add( nineJButton );
      nineJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when nineJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               nineJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener
      
      // set up zeroJButton
      zeroJButton = new JButton();
      zeroJButton.setBounds( 100, 130, 45, 20 );
      zeroJButton.setText( "0" );
      contentPane.add( zeroJButton );
      zeroJButton.addActionListener(

         new ActionListener() // anonymous inner class
         {
            // event handler called when zeroJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               zeroJButtonActionPerformed( event );
            }

         } // end anonymous inner class

      ); // end call to addActionListener

      // set up pointJButton
      pointJButton = new JButton();