presentvalue.java

32个java程序源代码

// Exercise 10.11: PresentValue.java
// Application that calculates how much money should be invested in
// order to achieve a certain financial goal.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.text.*;

public class PresentValue extends JFrame
{
   // JLabel and JTextField for future value
   private JLabel futureValueJLabel;
   private JTextField futureValueJTextField;

   // JLabel and JTextField for interest rate
   private JLabel interestRateJLabel;
   private JTextField interestRateJTextField;

   // JLabel and JSpinner for number of years
   private JLabel yearsJLabel;
   private JSpinner yearsJSpinner;

   // JLabel and JTextArea for initial amounts
   // needed to reach future value
   private JLabel amountNeededJLabel;
   private JTextArea amountNeededJTextArea;

   // JButton calculates initial amounts needed
   // to reach future value
   private JButton calculateJButton;
   
   // no-argument constructor
   public PresentValue()
   {
      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 futureValueJLabel
      futureValueJLabel = new JLabel();
      futureValueJLabel.setBounds( 20, 25, 90, 20 );
      futureValueJLabel.setText( "Future value:" );
      contentPane.add( futureValueJLabel );

      // set up futureValueJTextField
      futureValueJTextField = new JTextField();
      futureValueJTextField.setBounds( 130, 25, 100, 20 );
      futureValueJTextField.setText( "0" );
      futureValueJTextField.setHorizontalAlignment(
         JTextField.RIGHT );
      contentPane.add( futureValueJTextField );
      
      // set up interestRateJLabel
      interestRateJLabel = new JLabel();
      interestRateJLabel.setBounds( 20, 60, 90, 20 );
      interestRateJLabel.setText( "Interest rate:" );
      contentPane.add( interestRateJLabel );

      // set up interestRateJTextField
      interestRateJTextField = new JTextField();
      interestRateJTextField.setBounds( 130, 60, 100, 20 );
      interestRateJTextField.setText( "0" );
      interestRateJTextField.setHorizontalAlignment(
         JTextField.RIGHT );
      contentPane.add( interestRateJTextField );

      // set up yearsJLabel
      yearsJLabel = new JLabel();
      yearsJLabel.setBounds( 20, 95, 80, 20 );
      yearsJLabel.setText( "Years:" );
      contentPane.add( yearsJLabel );

      // set up yearsJSpinner
      yearsJSpinner = new JSpinner( 
         new SpinnerNumberModel() );      
      contentPane.add( yearsJSpinner );

      // set up amountNeededJLabel
      amountNeededJLabel = new JLabel();
      amountNeededJLabel.setBounds( 20, 130, 150, 20 );
      amountNeededJLabel.setText( "Annual amount needed:" );
      contentPane.add( amountNeededJLabel );

      // set up amountNeededJTextArea
      amountNeededJTextArea = new JTextArea();
      contentPane.add( amountNeededJTextArea );
      
      // set up calculateJButton
      calculateJButton = new JButton();
      calculateJButton.setBounds( 250, 25, 90, 20 );
      calculateJButton.setText( "Calculate" );
      contentPane.add( calculateJButton );
      calculateJButton.addActionListener( 
      
         new ActionListener() // anonymous inner class
         {
            // event handler called when calculateJButton is pressed
            public void actionPerformed( ActionEvent event )
            {
               calculateJButtonActionPerformed( event );
            }
            
         } // end anonymous inner class
         
      ); // end call to addActionListener
      
      // set properties of application's window
      setTitle( "Present Value Calculator" ); // set title bar text
      setSize( 370, 320 );                    // set window size
      setVisible( true );                     // display window
      
   } // end method createUserInterface
   
   // calculate and display amounts
   private void calculateJButtonActionPerformed( ActionEvent event )
   {
      int futureValue = Integer.parseInt( 
         futureValueJTextField.getText() );
      double rate = Double.parseDouble( 
         interestRateJTextField.getText() );
      
      amountNeededJTextArea.setText( "Year\tInitial Deposit" );
      DecimalFormat dollars = new DecimalFormat( "$0.00" );
      
      // for loop calculates total amount
      for ( ;; )  
      {
         
      } // end for

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

   } // end method main
   
} // end class PresentValue

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