Search and replace using regular expression groups

Regular expressions come in very handy for searching and replacing texts in data files. Most IDEs (eclipse on which this was tested) and text editors (TextPad, JEdit, etc.) support regular expressions. Take for example an input data file that you need to create/modify.
Here is the data file we are interested in...

07/10/09,11:10:20 AM,63463284,credit,salary electronic deposit,$1000.00
07/11/09,11:10:20 AM,63463284,credit,CD interest,$22.00
07/12/09,11:10:20 AM,63463284,credit,tax refund,$300.00
07/13/09,11:10:20 AM,63463284,credit,ATM deposit,$500.00
07/14/09,11:10:20 AM,63463284,debit,credit card payment,$137.00
07/15/09,11:10:20 AM,63463284,credit,checking a/c interest,$20.00
07/16/09,11:10:20 AM,63463284,debit,power bill,$80.00
07/17/09,11:10:20 AM,63463284,credit,Check #8774,$350.00
07/18/09,11:10:20 AM,63463284,debit,overdraft fee,$5.00
07/19/09,11:10:20 AM,63463284,credit,Check #167,$1000.00
07/10/09,11:10:20 AM,77667529,credit,salary electronic deposit,$2000.00
07/11/09,11:10:20 AM,77667529,credit,CD interest,$22.00
07/12/09,11:10:20 AM,77667529,credit,tax refund,$300.00
07/13/09,11:10:20 AM,77667529,credit,ATM deposit,$500.00
07/14/09,11:10:20 AM,77667529,debit,credit card payment,$137.00
07/15/09,11:10:20 AM,77667529,credit,checking a/c interest,$20.00
07/16/09,11:10:20 AM,77667529,debit,power bill,$80.00
07/17/09,11:10:20 AM,77667529,credit,Check #7766,$350.00
07/18/09,11:10:20 AM,77667529,debit,Check copy fee,$10.00
07/19/09,11:10:20 AM,77667529,credit,Check #125,$1000.00
07/10/09,11:10:20 AM,33445398,credit,salary electronic deposit,$2000.00
07/11/09,11:10:20 AM,33445398,credit,CD interest,$22.00
07/12/09,11:10:20 AM,33445398,credit,tax refund,$300.00
07/13/09,11:10:20 AM,33445398,credit,ATM deposit,$500.00
07/14/09,11:10:20 AM,33445398,debit,credit card payment,$137.00
07/15/09,11:10:20 AM,33445398,credit,checking a/c interest,$20.00
07/16/09,11:10:20 AM,33445398,debit,power bill,$80.00
07/17/09,11:10:20 AM,33445398,credit,Check #1255,$350.00
07/18/09,11:10:20 AM,33445398,debit,overdraft fee,$5.00
07/19/09,11:10:20 AM,33445398,credit,Check #433,$1000.00

The data is about bank transactions conducted on accounts.
Let's take a look at the first few lines of data...

Date Time account # type description currency amount
------- ------- --------------- ------- ------------------ -------------- ------------
07/10/09,11:10:20 AM,63463284,credit,salary electronic deposit,$1000.00
07/11/09,11:10:20 AM,63463284,credit,CD interest,$22.00
07/12/09,11:10:20 AM,63463284,credit,tax refund,$300.00
07/13/09,11:10:20 AM,63463284,credit,ATM deposit,$500.00
07/14/09,11:10:20 AM,63463284,debit,credit card payment,$137.00
07/15/09,11:10:20 AM,63463284,credit,checking a/c interest,$20.00
07/16/09,11:10:20 AM,63463284,debit,power bill,$80.00
07/17/09,11:10:20 AM,63463284,credit,Check #8774,$350.00
07/18/09,11:10:20 AM,63463284,debit,overdraft fee,$5.00
07/19/09,11:10:20 AM,63463284,credit,Check #167,$1000.00
..
..
..

Say we want to give credit to all overdraft fees charged for all accounts by adding an adjustment(credit) for the same amount. That is we want to add a new data line for every line which contains 'overdraft fee'. For example if you look at the lines of data above. For every line like this...
07/18/09,11:10:20 AM,63463284,debit,overdraft fee,$5.00
we want to add a new line like this....
07/18/09,11:10:20 AM,63463284,credit,overdraft fee adjustment,$5.00

The regular expression .*overdraft fee.*\n will get us the line containing overdraft fee. But we also need the timestamp at the beginning of the line. So let's refine the search string by adding a group.
^(.*)debit,overdraft fee,(.*)\n
So everything from the start of line upto debit forms group 1, which is the timestamp and account number.
The replacement string should be the entire last line which is $0 plus the same timestamp and account number($1) plus new text (credit,overdraft fee adjustment, $2) plus platform independent line feed (\R). Putting them all together the replacement string should be
$0$1credit,overdraft fee adjustment,$2\R
This was tested in eclipse IDE. In case of text editors like Textpad, the search string will be
^\\(.*\\)debit,overdraft fee,\\(.*\\)\n
and the replace string will be \0\1credit,overdraft fee adjustment,\2\n

Using the search and replace sub menu item of eclipse

Java System Tray icon in Ubuntu

Download JDIC.

• Using Synaptic package manager
  search for jdic and download both libjdic -java and libjdic-bin packages.

• downloading from JDIC website
  download the linux distribution from here.
  Say you extract it to the directory /home/myuser/jdic
  You should see a linux folder which has jdic.jar and some .so files.
  

Here is a code example for creating a tray icon.

// Start Tray Icon Code
SystemTray tray = SystemTray.getDefaultSystemTray();
TrayIcon ti;

try {
if (Integer.parseInt(System.getProperty("java.version").substring(2, 3)) >= 5)
System.setProperty("javax.swing.adjustPopupLocationToFit", "false");
menu = new JPopupMenu("MY APP Menu");

// "Quit" menu item
menuItem = new JMenuItem("Exit");
menuItem.addActionListener(this);
menu.add(menuItem);

ImageIcon i = new ImageIcon(MyClass.class.getResource("/images/appImage.png"));

ti = new TrayIcon(i, "Welcome to My App", menu);

ti.setIconAutoSize(true);
ti.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
            MyApp.this.setVisible(!MyApp.this.isVisible());
            if (MyAppFrame.this.isVisible() == false) {
                     ti.displayMessage(
                                             "Welcome to MyApp",
          "To open  MyApp Application click the icon. To exit the application right click the icon and click the Quit menu item.",
          0);
            }
 }
});

tray.addTrayIcon(ti);

// Construct the GUI for balloon message.
ActionListener al = new ActionListener() {

public void actionPerformed(ActionEvent e) {
MyApp.this.setVisible(!MyApp.this.isVisible());
if (MyApp.this.isVisible() == false) {
ti.displayMessage(
  "MyApp",
   "To open the MyApp Application click the icon. To exit the application right click the icon and click the Quit menu item.",
                                          0);
          }
}
};
exitMnu.addActionListener(al);

} catch (Exception e) {
logger.error("Unhandled error", e);
}

try {
this.setIconImage(new ImageIcon(MyApp.class
  .getResource("/images/myApp.png")).getImage());
} catch (Exception e) {
logger.error("Unhandled error", e);
}
// End Tray Icon Code        

For this to work, you need to add jdic jar to the build path and also add share library files location(/usr/lib/jni for the first case and /home/myuser/jdic/linux for the second) to the native library path for the project as shown in the picture below.

Mounting windows partition at bootup in Ubuntu

I have a dual booting linux system at work. I share the java projects (located on the windows partition) on both windows and Linux. But when I launch eclipse, all the projects show up closed since the windows partition is not mounted yet. The solution to this is to mount windows partition at boot up time.

To mount a windows partition at startup, you need to do the following.
- get the UUID of the device

blkid
/dev/sda1: UUID="9044866844865140" TYPE="ntfs" 
/dev/sda2: LABEL="GHOST DATA" UUID="FCF8-3D81" TYPE="vfat"
/dev/sda5: UUID="b2293182-981b-4291-96ff-dba50f73510d" TYPE="ext3"
/dev/sda6: TYPE="swap" UUID="1d3b683c-c559-43e2-ac46-f3500e27dbfd"

- create an entry in /etc/fstab file for the windows NTFS drive

# <file system> <mount point>   <type>  <options>       <dump>  <pass>
UUID="9044866844865140" /media/disk ntfs-3g defaults,locale=en_US.utf8 0 0

Instead of UUID specifying the device also works. see below

/dev/sda1 /media/disk ntfs-3g defaults,locale=en_US.utf8 0 0 

Note : both ntfs and ntfs-3g works fine for a windows partition.

The options for fstab are clearly explained in the ubuntu help docs here.