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- 12-13-2008, 01:04 AM #1
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unreachable statement - Java calculator program
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
- Java Code:
for (int i = 1; 1 <= 3; i++)
(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.Last edited by Fubarable; 12-13-2008 at 01:28 AM.
- 12-13-2008, 01:49 AM #3
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D'oh!
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.
-
You're welcome.
The reason I recommend the curly braces has little to do with neatness actually. Imagine you have this code:
Java Code:int i = 0; for (i = 0; i < myButtons.length; i++) myButtons[i] = new JButton("Button " + i);
Java Code: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.
Java Code: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. }
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