Equal button root of problem?

[Squirrel RJ]

Everything works fine, yet the calculator doesn't calculate, any ideas where I went wrong?

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);

	// construct and populate 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);

	// assign an 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\nOpenExhibit Software\nCopyright 2007\nAll rights reserved";
		JOptionPane.showMessageDialog(null,message,"About Calculator", JOptionPane.
		INFORMATION_MESSAGE);
	}

	// test for button clicks
	foundKey = false;

	// search for the 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 = 1; // 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:
								op1 -= Double.parseDouble(lcd.getText());
								break;
							case 13:
								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 and add to frame
		Image icon = Toolkit.getDefaultToolkit().getImage("calcImage.gif");
		f.setIconImage(icon);

	} // end of main
} // end of class