prog. using radio buttons for simple calculator

import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*;

class Calculator extends JFrame { private final Font BIGGER_FONT = new Font("monspaced", Font.PLAIN, 20); private JTextField textfield;
private boolean number = true;
private String equalOp = "=";
private CalculatorOp op = new CalculatorOp();

public Calculator() { textfield = new JTextField("0", 12); textfield.setHorizontalAlignment(JTextField.RIGHT); textfield.setFont(BIGGER_FONT);

ActionListener numberListener = new NumberListener(); String buttonOrder = "1234567890 "; JPanel buttonPanel = new JPanel(); buttonPanel.setLayout(new GridLayout(4, 4, 4, 4)); for (int i = 0; i < buttonOrder.length(); i++) { String key = buttonOrder.substring(i, i+1); if (key.equals(" ")) { buttonPanel.add(new JLabel("")); } else { JButton button = new JButton(key); button.addActionListener(numberListener); button.setFont(BIGGER_FONT); buttonPanel.add(button); } } ActionListener operatorListener = new OperatorListener(); JPanel panel = new JPanel(); panel.setLayout(new GridLayout(4, 4, 4, 4)); String[] opOrder = {"+", "-", "*", "/","=","C"}; for (int i = 0; i < opOrder.length; i++) { JButton button = new JButton(opOrder[i]); button.addActionListener(operatorListener); button.setFont(BIGGER_FONT); panel.add(button); } JPanel pan = new JPanel(); pan.setLayout(new BorderLayout(4, 4)); pan.add(textfield, BorderLayout.NORTH ); pan.add(buttonPanel , BorderLayout.CENTER); pan.add(panel , BorderLayout.EAST ); this.setContentPane(pan); this.pack(); this.setTitle("Calculator"); this.setResizable(false); } private void action() { number = true;
textfield.setText("0"); equalOp = "="; op.setTotal("0"); } class OperatorListener implements ActionListener { public void actionPerformed(ActionEvent e) { if (number) { action(); textfield.setText("0"); } else { number = true; String displayText = textfield.getText(); if (equalOp.equals("=")) { op.setTotal(displayText); } else if (equalOp.equals("+")) { op.add(displayText); } else if (equalOp.equals("-")) { op.subtract(displayText); } else if (equalOp.equals("*")) { op.multiply(displayText); } else if (equalOp.equals("/")) { op.divide(displayText); } textfield.setText("" + op.getTotalString()); equalOp = e.getActionCommand(); } } } class NumberListener implements ActionListener { public void actionPerformed(ActionEvent event) { String digit = event.getActionCommand(); if (number) { textfield.setText(digit); number = false; } else { textfield.setText(textfield.getText() + digit); } } } public class CalculatorOp {

private int total;
public CalculatorOp() { total = 0; } public String getTotalString() { return ""+total; } public void setTotal(String n) { total = convertToNumber(n); } public void add(String n) { total += convertToNumber(n); } public void subtract(String n) { total -= convertToNumber(n); } public void multiply(String n) { total *= convertToNumber(n); }

public void divide(String n) {
    total /= convertToNumber(n);
}

private int convertToNumber(String n) {
    return Integer.parseInt(n);
}

}

}