public CalculatorPanel() {
result = 0;
lastCommand = "+";
ActionListener command = new CommandAction();
GridLayout layout = new GridLayout(2, 5);
layout.setHgap(5);
layout.setVgap(5);
panel = new JPanel();
panel.setLayout(layout);
panel.setPreferredSize(new Dimension(400, 200));
// add display
display = new JTextField();
Command = new JTextField("+");
firstNumber = new JTextField();
secondNumber = new JTextField();
JTextField equal = new JTextField("=");
equal.setEnabled(false);
display.setEnabled(false);
Command.setEnabled(false);
panel.add(firstNumber);
panel.add(Command);
panel.add(secondNumber);
panel.add(equal);
panel.add(display);
addButton("+", command);
addButton("-", command);
addButton("*", command);
addButton("/", command);
addButton("OK", command);
add(panel, BorderLayout.CENTER);
}
