Hello I am working on a Java Investment Calculator. I need to add a few aspects

Question

Hello I am working on a Java Investment Calculator. I need to add a few aspects to the program. Please help!

1. I need to add a menu bar with an "Operations" button, under this button need to be a Calculate and to Exit button.

2. i need to fix the calculated amount to return correctly!!

My program so far:

package investcalc;

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class InvestCalc extends JFrame
{
private JTextField jtfInvestmentAmount, jtfYears,
jtfAnnualInterestRate, jtfFutureValue;
private JButton jbtCalculate = new JButton("Calculate");
public InvestCalc()
{
JPanel p1 = new JPanel();
p1.setLayout(new GridLayout(4, 2));
p1.add(new JLabel("Investment Amount"));
p1.add(jtfInvestmentAmount = new JTextField(16));
p1.add(new JLabel("Years"));
p1.add(jtfYears = new JTextField(16));
p1.add(new JLabel("Annual Interest Rate"));
p1.add(jtfAnnualInterestRate = new JTextField(16));
p1.add(new JLabel("Future value"));
p1.add(jtfFutureValue = new JTextField(16));
JPanel p2 = new JPanel(new FlowLayout(FlowLayout.RIGHT));
p2.add(jbtCalculate);
jtfInvestmentAmount.setHorizontalAlignment(JTextField.RIGHT);
jtfYears.setHorizontalAlignment(JTextField.RIGHT);
jtfAnnualInterestRate.setHorizontalAlignment(JTextField.RIGHT);
jtfFutureValue.setHorizontalAlignment(JTextField.RIGHT);
jtfFutureValue.setEditable(false);
jbtCalculate.setMnemonic('C');
setLayout(new BorderLayout());
add(p1, BorderLayout.CENTER);
add(p2, BorderLayout.SOUTH);
jbtCalculate.addActionListener(
new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
int investmentAmount = Integer.parseInt(jtfInvestmentAmount.getText());
int years = Integer.parseInt(jtfYears.getText());
double annualInterestRate = Double.parseDouble(jtfAnnualInterestRate.getText());
double futureValue = investmentAmount *
(power(annualInterestRate + 1, years * 12));
jtfFutureValue.setText("" + futureValue);
}
});
}
public static double power(double rate, int years)
{
double power = 1;
for (int i = 1; i <= years; i++)
{
power*= rate;
}
return power;
}
public static void main(String[] args)
{
JFrame frame = new InvestCalc();
frame.setTitle("Investment Calculation");
frame.pack();
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

Explanation / Answer

import java.awt.*;
import java.awt.event.*;
import java.awt.datatransfer.*;
import java.text.DecimalFormat;
import javax.swing.JOptionPane;
public class Calculator extends Frame implements ActionListener

{

private Button keys[];

private Panel keypad;

private TextField lcd;

private double op1;

private boolean first;

private boolean foundKey;

private boolean clearText;

private int lastOp;

private DecimalFormat calcPattern;

public Calculator()

{

// create an instance of the menu

MenuBar mnuBar = new MenuBar();

setMenuBar(mnuBar);

// create an instance of the File menu

Menu mnuFile = new Menu("File", true);

mnuBar.add(mnuFile);

MenuItem mnuFileExit = new MenuItem("Exit");

mnuFile.add(mnuFileExit);

// construct and populate the Edit menu

Menu mnuEdit = new Menu("Edit", true);

mnuBar.add(mnuEdit);

MenuItem mnuEditClear = new MenuItem("Clear");

mnuEdit.add(mnuEditClear);

mnuEdit.insertSeparator(1);

MenuItem mnuEditCopy = new MenuItem("Copy");

mnuEdit.add(mnuEditCopy);

MenuItem mnuEditPaste = new MenuItem("Paste");

mnuEdit.add(mnuEditPaste);

// construct and populate the About menu

Menu mnuAbout = new Menu("About", true);

mnuBar.add(mnuAbout);

MenuItem mnuAboutCalculator = new MenuItem("About Calculator");

mnuAbout.add(mnuAboutCalculator);

// add the ActionListener to each menu item

mnuFileExit.addActionListener(this);

mnuEditClear.addActionListener(this);

mnuEditCopy.addActionListener(this);

mnuEditPaste.addActionListener(this);

mnuAboutCalculator.addActionListener(this);

// add the ActionCommand to each menu item

mnuFileExit.setActionCommand("Exit");

mnuEditClear.setActionCommand("Clear");

mnuEditCopy.setActionCommand("Copy");

mnuEditPaste.setActionCommand("Paste");

mnuAboutCalculator.setActionCommand("About");

// construct components and initialize beginning values

lcd = new TextField(20);

lcd.setEditable(false);

keypad = new Panel();

keys = new Button[16];

first = true;

op1 = 0.0;

clearText = true;

lastOp = 0;

calcPattern = new DecimalFormat("#######.#######");

// construct and assign captions to the Buttons

for (int i=0; i<=9; i++)

keys[i] = new Button(String.valueOf(i));

keys[10] = new Button("/");

keys[11] = new Button("*");

keys[12] = new Button("-");

keys[13] = new Button("+");

keys[14] = new Button("=");

keys[15] = new Button(".");

// set Frame and keypad layout to grid layout

setLayout(new BorderLayout());

keypad.setLayout(new GridLayout(4,4,10,10));

for (int i=7; i<=10; i++) // 7, 8, 9, divide

keypad.add(keys[i]);

for (int i=4; i<=6; i++) // 4, 5, 6

keypad.add(keys[i]);

keypad.add(keys[11]); // multiply

for (int i=1; i<=3; i++) // 1, 2, 3

keypad.add(keys[i]);

keypad.add(keys[12]); // subtract

keypad.add(keys[0]); // 0 key

for (int i=15; i>=13; i--)

keypad.add(keys[i]); // decimal point, =, add (+) keys

for (int i=0; i<keys.length; i++)

keys[i].addActionListener(this);

add(lcd, BorderLayout.NORTH);

add(keypad, BorderLayout.CENTER);

addWindowListener(

new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit(0);

}

}

);

} // end of constructor method   

public void actionPerformed(ActionEvent e)

{

// test for menu item clicks

String arg = e.getActionCommand();

if (arg == "Exit")

System.exit(0);

if (arg == "Clear")

{

clearText = true;

first = true;

op1 = 0.0;

lcd.setText("");

lcd.requestFocus();

}

if (arg == "Copy")

{

Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard();

StringSelection contents = new StringSelection(lcd.getText());

cb.setContents(contents, null);

}

if (arg == "Paste")

{

Clipboard cb = Toolkit.getDefaultToolkit().getSystemClipboard();

Transferable content = cb.getContents(this);

try

{

String s = (String)content.getTransferData(DataFlavor.stringFlavor);

lcd.setText(calcPattern.format(Double.parseDouble(s)));

}

catch (Throwable exc)

{

lcd.setText("");

}

}

if (arg == "About")

{

String message = "Calculator ver. 1.0 OpenExhibit Software Copyright 2007 All rights reserved";

JOptionPane.showMessageDialog(null,message, "About Calculator", JOptionPane.INFORMATION_MESSAGE);

}

// test for button clicks

foundKey = false;

// search for clicked key

for (int i=0; i<keys.length && !foundKey; i++)

{

if(e.getSource() == keys[i])

{

foundKey = true;

switch(i)

{

// number and decimal point buttons

case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8: case 9: case 15:

if(clearText)

{

lcd.setText("");

clearText = false;

}

lcd.setText(lcd.getText() + keys[i].getLabel());

break;

// operator buttons

case 10: case 11: case 12: case 13: case 14:

clearText = true;

if (first) //first operand

{

if(lcd.getText().length()==0) op1 = 0.0;

else op1 = Double.parseDouble(lcd.getText());

first = false;

clearText = true;

lastOp = i; // save last operator

}

else // second operand

{

switch(lastOp)

{

case 10: //divide button

op1 /=Double.parseDouble(lcd.getText());

break;

case 11: //multiply button

op1 *=Double.parseDouble(lcd.getText());

break;

case 12: //minus button

op1 -=Double.parseDouble(lcd.getText());

break;

case 13: //plus button

op1 +=Double.parseDouble(lcd.getText());

break;

} //end of switch(lastOp)

lcd.setText(calcPattern.format(op1));

clearText = true;

if (i==14) first = true; //equal button

else lastOp = i; //save last operator

} //end else

break;

} //end of switch(i)

} //end of if

} //end of for

} //end of actionPerformed

public static void main(String args[])

{

//set frame properties

Calculator f = new Calculator();

f.setTitle("Calculator Application");

f.setBounds(200,200,300,300);

f.setVisible(true);

//set image properties

Image icon = Toolkit.getDefaultToolkit().getImage("calcImage.gif");

f.setIconImage(icon);

} //end of main

} //end of class

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