In Java - Part 1 - Improve the output quality of the investment application in S

Question

In Java -

Part 1 - Improve the output quality of the investment application in Section 10.3.2. Format the numbers with two decimal digits, using the String.format method. Set the font of the text area to a fixed width font, using the call

textArea.setFont(new Font(Font.MONOSPACED, Font.PLAIN, 12));

Part 2 - Add error handling to the program in Section 10.3.2. If the interest rate is not a floating-point number, or if it less than 0, display an error message, using a JOptionPane (see Special Topic 2.5).

PLEASE USE JAVADOC AND CODE COMMENT

PLEASE INDICATE HOW MANY CLASSES OR PACKAGES SHOULD BE CREATED. Appreciate if you could include images of your code. I use Eclipse

Here is the code:

Explanation / Answer

here is your modified code : ----------------->>>>>>>>>>>>

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import java.awt.Font;

public class InvestmentFrame3 extends JFrame{
private static final int FRAME_WIDTH = 400;
private static final int FRAME_HEIGHT = 250;
private static final int AREA_ROWS = 10;
private static final int AREA_COLUMNS = 30;
private static final double DEFAULT_RATE = 5;
private static final double INITIAL_BALANCE = 1000;

private JLabel rateLabel;
private JTextField rateField;
private JButton button;
private JTextArea resultArea;
private double balance;

public InvestmentFrame3(){
  balance = INITIAL_BALANCE;
  resultArea = new JTextArea(AREA_ROWS,AREA_COLUMNS);

  resultArea.setFont(new Font(Font.MONOSPACED,Font.PLAIN,12));
  resultArea.setText(String.format("%.2f",balance)+" ");
  resultArea.setEditable(false);

  createTextField();
  createButton();
  createPanel();

  setSize(FRAME_WIDTH,FRAME_HEIGHT);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

private void createTextField(){
  rateLabel = new JLabel("Interest Rate: ");

  final int FIELD_WIDTH = 10;
  rateField = new JTextField(FIELD_WIDTH);
  rateField.setText(" "+DEFAULT_RATE);
}

class AddInterestListener implements ActionListener{
  public void actionPerformed(ActionEvent event){
   double rate = -2;
   try{
    rate = Double.parseDouble(rateField.getText());
    if(rate < 0){
     throw new Exception("");
    }
    double interest = balance * rate / 100;
    balance = balance + interest;
    resultArea.append(String.format("%.2f",balance)+" ");
   }catch(Exception e){
    JOptionPane.showMessageDialog(null,"Interest Rate is Not Valid !!!");
   }

  }
}

private void createButton(){
  button = new JButton("Add Interest");
  ActionListener listener = new AddInterestListener();
  button.addActionListener(listener);
}

private void createPanel(){
  JPanel panel = new JPanel();
  panel .add(rateLabel);
  panel.add(rateField);
  panel.add(button);
  JScrollPane scrollPane = new JScrollPane(resultArea);
  panel.add(scrollPane);
  add(panel);
}

public static void main(String[] args) {
  InvestmentFrame3 f = new InvestmentFrame3();
  f.setVisible(true);
}
}

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