unreachable statement - Java calculator program

[V2001Gordon]

Hello - long time reader, first time poster! I would greatly appreciate any help with the "unreachable statement" error I am getting when compiling this application! (am getting it on the line that says keypad.add(keys[12]); //subtract (I thought maybe there was a missing return statement.. but no..?) Thank you for any insights offered!:confused:

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()
{
//mnu
MenuBar mnuBar = new MenuBar();
setMenuBar(mnuBar);

//file mnu
Menu mnuFile = new Menu("File",true);
mnuBar.add(mnuFile);
MenuItem mnuFileExit = new MenuItem("Exit");
mnuFile.add(mnuFileExit);

//edit mnu
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);

//about mnu
Menu mnuAbout = new Menu("About",true);
mnuBar.add(mnuAbout);
MenuItem mnuAboutCalculator = new MenuItem("About");
mnuAbout.add(mnuAboutCalculator);

//ActionListener
mnuFileExit.addActionListener(this);
mnuEditClear.addActionListener(this);
mnuEditCopy.addActionListener(this);
mnuEditPaste.addActionListener(this);
mnuAboutCalculator.addActionListener(this);

//ActionCommand
mnuFileExit.setActionCommand("Exit");
mnuEditClear.setActionCommand("Clear");
mnuEditCopy.setActionCommand("Copy");
mnuEditPaste.setActionCommand("Paste");
mnuAboutCalculator.setActionCommand("About");

//init
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("########.########");

//butt. capt.
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(".");

//frame
setLayout(new BorderLayout());
keypad.setLayout(new GridLayout(4,4,10,10));

for (int i=7; i<=10; i++) //7-9 div
keypad.add(keys[i]);

for (int i=4; i<=6; i++) // 4-6
keypad.add(keys[i]);

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

for (int i=1; 1<=3; i++) //1-3
keypad.add(keys[i]);

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

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

for (int i=15; i>=13; i--)
keypad.add(keys[i]); //.,=,+

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 const.

public void actionPerformed(ActionEvent e)
{
//click
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.stringF lavor);
lcd.setText(calcPattern.format(Double.parseDouble( s)));
}
catch (Throwable exc)
{
lcd.setText("");
}

return;
}

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);
}

//buttonclk
foundKey = false;

//clkd key
for (int i=0; i<keys.length && !foundKey; i++)
{
if(e.getSource() == keys[i])
{
foundKey = true;
switch(i)
{
//num dec btns
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;

//op butns
case 10: case 11: case 12: case 13: case 14:
clearText = true;

if (first) //1st op
{
if(lcd.getText().length()==0) op1 = 0.0;
else op1 = Double.parseDouble(lcd.getText());

first = false;
clearText = true;
lastOp = i; //save op
}
else //2nd op
{
switch(lastOp)
{
case 10: //div
op1 /= Double.parseDouble(lcd.getText());
break;
case 11: // *
op1 *= Double.parseDouble(lcd.getText());
break;
case 12: // -
op1 -= Double.parseDouble(lcd.getText());
break;
case 13: //+
op1 += Double.parseDouble(lcd.getText());
break;
} //endswitch
lcd.setText(calcPattern.format(op1));
clearText = true;

if(i==14) first = true; //=
else lastOp = i; //save last
} //end else
break;
} //end swtch i
} //endif
} //endfor
} //endaction

public static void main(String args[])
{
//set frame properties
Calculator f = new Calculator();
f.setTitle("Calculator");
f.setBounds(200,200,300,300);
f.setVisible(true);

//img
Image icon = Toolkit.getDefaultToolkit().getImage("calcImage.gi f");
f.setIconImage(icon);
} //end mn
} //end class

[Fubarable]

for (int i = 1; 1 <= 3; i++)

look carefully at this loop. See anything wrong with it? This loop will never end. Why?

(you'll smack your head when you figure this out).

Also, why not move up to Swing and leave out of date AWT behind?

A moral to this problem is that when you encounter this type of error, you will need to look at a line or two above the error to see why it is occurring. Also, if my hint doesn't help you solve this, please post back and someone will give the answer.

a final (I think) suggestion: put all for / while loops and if / else / ... blocks within curly braces even if only one line long. This isn't the cause of your current problem, but will likely be a cause of a future problem if you don't do this.

Best of luck.

[V2001Gordon]

THANKS... that is what happens when you look and look and overlook some more! That pesky "1" vs "i"... thanks for saving my sanity! (And yes, I did smack my head...)

And also thank you for the suggestions. I think I will try this also with Swing and try to "neat up" my code as you mentioned, too.

for (int i = 1; 1 <= 3; i++)

look carefully at this loop. See anything wrong with it? This loop will never end. Why?

(you'll smack your head when you figure this out).

Also, why not move up to Swing and leave out of date AWT behind?

A moral to this problem is that when you encounter this type of error, you will need to look at a line or two above the error to see why it is occurring. Also, if my hint doesn't help you solve this, please post back and someone will give the answer.

a final (I think) suggestion: put all for / while loops and if / else / ... blocks within curly braces even if only one line long. This isn't the cause of your current problem, but will likely be a cause of a future problem if you don't do this.

Best of luck.

[Fubarable]

You're welcome.

The reason I recommend the curly braces has little to do with neatness actually. Imagine you have this code:

int i = 0;
for (i = 0; i < myButtons.length; i++)
  myButtons[i] = new JButton("Button " + i);

and you want to change it so that the JButtons are added to a JPanel. If you don't use curly braces, bad things can happen here:

int i = 0;
for (i = 0; i < myButtons.length; i++)
  myButtons[i] = new JButton("Button " + i);
  myPanel.add(myButtons[i]); // this code isn't doing what you want it to be doing.

much better is this:

for (int i = 0; i < myButtons.length; i++)
{
  myButtons[i] = new JButton("Button " + i);
  myPanel.add(myButtons[i]); // this code isn't doing what you want it to be doing.
}