Action Listener troubles

Question

I'm having trouble with my small applet.

public CdProgram()
   {
             //Create the four labels
      amountL = new JLabel("Enter the amount deposited: ",
                                  SwingConstants.RIGHT);
      yearsL = new JLabel("Enter the years: ",
                                  SwingConstants.RIGHT);
      interestL = new JLabel("Enter the interest rate: ", SwingConstants.RIGHT);
      certificateL = new JLabel("Certificate: ",
                                  SwingConstants.RIGHT);

             //Create the four text fields
      amountTF = new JTextField(10);
      yearsTF = new JTextField(10);
      interestTF = new JTextField(10);
      certificateTF = new JTextField(10);

             //Create Calculate Button
      calculateB = new JButton("Calculate");
      cbHandler = new CalculateButtonHandler();
      calculateB.addActionListener(cbHandler);

             //Create Exit Button
      exitB = new JButton("Exit");
      ebHandler = new ExitButtonHandler();
      exitB.addActionListener(ebHandler);

             //Set the title of the window
      setTitle("Certificate of amount on maturity");

             //Get the container
      Container pane = getContentPane();

             //Set the layout
      pane.setLayout(new GridLayout(5, 2));

             //Place the components in the pane
      pane.add(amountL);
      pane.add(amountTF);
      pane.add(yearsL);
      pane.add(yearsTF);
      pane.add(interestL);
      pane.add(interestTF);
      pane.add(certificateL);
      pane.add(certificateTF);
      pane.add(calculateB);
      pane.add(exitB);

             //Set the size of the window and display it
      setSize(WIDTH, HEIGHT);
      setVisible(true);
      setDefaultCloseOperation(EXIT_ON_CLOSE);
   }



   public static void main(String[] args)
   {
       CdProgram CertObjt = new CdProgram();
   }
}


private class CalculateButtonHandler implements ActionListener
   {
      public void actionPerformed(ActionEvent e)
      {
         double amount, years, interst, certificate;

         amount = Double.parseDouble(amountTF.getText());
         years = Double.parseDouble(yearsTF.getText());
         interest = Double.parseDouble(interestTF.getText());
         certificate = amount * Math.pow(1 + rate/100, years);

         certificateTF.setText("" + certificate);
      }
   }

private class ExitButtonHandler implements ActionListener
   {
       public void actionPerformed(ActionEvent e)
       {
           System.exit(0);
       }
   }

My sub classes are not recognizing when i implement the action listener feature so i keep getting errors like:

CalculateButtonHandler.java:1: error: cannot find symbol
private class CalculateButtonHandler implements ActionListener

CalculateButtonHandler.java:3: error: cannot find symbol
      public void actionPerformed(ActionEvent e)

CdProgram.java:39: error: method addActionListener in class AbstractButton cannot be applied to given types;
      calculateB.addActionListener(cbHandler);
                ^
  required: ActionListener
  found: CalculateButtonHandler

Im not quite sure what I am doing wrong here. Thanks for the help.

Answer 1

i think you have to make your sub classes inner classes, like that they can talk directly with your principal classe, and change attributes with each other.

so try this and see:

alculateB.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent e)
      {
         double amount, years, interst, certificate;

         amount = Double.parseDouble(amountTF.getText());
         years = Double.parseDouble(yearsTF.getText());
         interest = Double.parseDouble(interestTF.getText());
         certificate = amount * Math.pow(1 + rate/100, years);

         certificateTF.setText("" + certificate);
      }
   });

exitB.addActionListener(new ActionListener(){
       public void actionPerformed(ActionEvent e)
       {
           System.exit(0);
       }
   });

let us know if it's working ;)