Delete and reaname oprations on text files??

Hi all,
I wonder how we can rename and delete a text file in java?
any comment will be appreciated.
abd

Consult the API (java.io.File)
You'll find the methods delete() and renameTo().

Similar Messages

Reading and writing to a text file from an Applet

I'm a novice java programming with very little formal programming training. I've pieced together enough knowledge to do what I've wanted to do so far...
However, I've been unable to figure out how to read and write to a text file from an Applet (I can do it from a normal java program just fine). Here is a simple example of what I'd like to do (you can also look at it on my website: www.stat.colostate.edu/~leach/test02/test02.html). I know that there is some problem with permission/security but I'm not smart enough to understand what the error messages are telling or understand the few books I have. If anyone can tell me how to get this applet to work, or direct me to some referrences that would help me out I'd really appreciate it.
Thanks,
Andy
import java.applet.Applet;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.io.*;
public class test02 extends Applet {
public Button B_go;
public GridBagConstraints c;
public void init() {
this.setLayout(new GridBagLayout());
c = new GridBagConstraints();
c.fill = GridBagConstraints.BOTH;
B_go = new Button("GO");
c.gridx=1; c.gridy=0; c.gridwidth=1; c.gridheight=1;
c.weightx = c.weighty = 0.0;
B_go.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
print_stuff();
setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
this.add(B_go,c);
public static void print_stuff() {
try{
File f = new File("test02.txt");
PrintWriter out = new PrintWriter(new FileWriter(f));
out.print("This is test02.txt");
out.close();
}catch(IOException e){**/}
}

I have almost the exact same problem, and I am in the same situation as you are with respects to the language.
I am simply trying to create a file and output some garbage to it but my applet always spits back a security violation. I've tried eliminating the restrictions on the applet runner I use but I still get the error.
My method:
debug = new Label() ;
debug.setLocation( 20, 20 ) ;
debug.setSize( 500, 15 ) ;
add( debug ) ;
// output
try
     OutputStream file = new FileOutputStream( new File( "" + getCodeBase() + "output.txt" ) ) ;
     byte[] buffer = { 1, 2, 3, 4, 5 } ;
     file.write( buffer ) ;
     file.close() ;
} catch( Exception e )
     debug.setText( e.toString() ) ;
     Can anyone tell why this isnt working?

I have to average data of 1min and then log into text file

For my application i have to average data of 1min and then log into text file. please guide me on this . To transfer the data i am using notifier.
Prashant Soni
LabVIEW Engineer

hi prashant,
Check this attachment..I just implemented my idea in this one.
Thanks and regards,
srikrishnaNF
Attachments:
Example_VI_BD.png ‏12 KB

By Java how to delete some lines in a text file containg some character?

Hello All,
I am having a text file [Basically It is a Sql File]. its containing some commented lines.
All i need to do is, By using a java Method I have to delete All the commented lines in That file .....
For Example if My file is like following.
/**** Commented By Kannan *********/
Select * From Employee;
go
/******************** Commented by Others ********/
Select * From DevMembers;
go
/*** Ends here **********/
And the output file would be
Select * From Employee;
go
select * From DevMembers;
go
can Anyone Help me in this regards,
Akram Kannan

BufferedReader should probably wrap the FileReader if you will be reading line-by-line. Same with the Writer.
And a simple -
if ( "/*".equals(record.substring(0,1) ) ... should handle the comment locations bit.
Message was edited by:
abillconsl

How can i delete a UserName from a text file using Strings or io.

hi i m trainee
i have been assigned to make java program which deletes a UserName and
his Passwor from a Text File
i m unable to do it using the code below
plz help
do reply
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java .applet.*;
import java.io.*;
class Del extends JFrame implements ActionListener
     String s2;
     JTextField CWDMUserDText = new JTextField();
     JButton CWDMSecDelButton = new JButton("DELETE");
     JLabel CWDMUserLabel = new JLabel("USER NAME");
     JPasswordField CWDMPassDText = new JPasswordField();
     JLabel CWDMPassLabel = new JLabel("PASSWORD");
     //String user,pass;
     /* CONSTRUCTOR*/
          Del()
               Container contentPane=getContentPane();
               contentPane.setLayout(null);
              setLocation(400,200);
               contentPane.add(CWDMUserDText);
               contentPane.add(CWDMSecDelButton);
               contentPane.add(CWDMUserLabel);
               contentPane.add(CWDMPassDText);
               contentPane.add(CWDMPassLabel);
              CWDMUserLabel.setBounds(20,70,100,25);
              CWDMPassLabel.setBounds(20,100,100,25);
               CWDMUserDText.setBounds(150,70,100,25);
               CWDMPassDText.setBounds(150,100,100,25);
               CWDMSecDelButton.setBounds(80,135,100,25);
               CWDMUserDText.addActionListener(this);
               CWDMPassDText.addActionListener(this);
               CWDMSecDelButton.addActionListener(this);
               contentPane.setBackground(Color.CYAN);
               setVisible(true);
               setDefaultCloseOperation(EXIT_ON_CLOSE);
     public void actionPerformed(ActionEvent ae)
              if(ae.getSource()==CWDMSecDelButton)
     //             user = CWDMUserDText.getText();
     //          pass = CWDMPassDText.getText();
     //          showarr();
               s2 = CWDMUserDText.getText();
               CWDMUserDText.setText("");
               CWDMPassDText.setText("");
               DelUser(s2);
          public static void main(String args[])
               Del myframe1= new Del();
               myframe1.setSize(300,200);
               myframe1.setVisible(true);
          public void DelUser(String s)
               //int a;
               try
                    FileReader fr = new FileReader("file.txt");
                    BufferedReader br = new BufferedReader(fr);
                   String s1;
                   int a;
                   int len = s.length();
                   System.out.println(len);
                   //s2 = CWDMUserDText.getText();
                    while ((s1=br.readLine()) !=null)
                         if((a=s1.indexOf(s))>0 && (a=s1.indexOf(s))!=0)
                              System.out.println(a);
                    fr.close();
               catch(FileNotFoundException e)
                    System.out.println("exception occured");
               catch(IOException e)
                    System.out.println("io");
     }

Some tips:
1) If you are adding or deleting stuff from a text file you need to write a new, modified file and then, optionally, do something like:
rename the old file to whatever.bak or the like.
rename the new file to the old.
2) Don't depend on System.out so much on a GUI application. For example if you get an exception use javax.swing.JOptionPane to display an alert (and show the message from the exception). You can write the stack trace to System.out if you want.
3) Don't muck about with calculating bounds for screen objects, let a layout manager sort it out. I like BoxLayoutManager for most things like this.
4) For bonus points do your IO in a separate Thread. Generally you don't want anything happening in an actionPerformed method which significantly delays it's return. The method should launch a new Thread to do the job, and disable the button until the Thread finishes.

Deleting a column in a text file using LabVIEW

Hello all,
I'm trying to delete the first column of my tab delimited text file using LabVIEW and then save it under the same file name. Can someone show me a quick way to perform this operation. Is this even possible with LabVIEW? Any help would be much appreciated.
My purpose is to automate this operation for hundreds of daily text files containing data that needs processing. I'm currently using LabVIEW 8.2.
Thanks!
-noviceLabVIEWuser

If the file is relatively small:
Read the file using the Read from Spreadsheet File VI to get 2D array.
Remove the column from the 2D array.
Write out new 2D array to new file using Write to Spreadsheet File VI.
If the file is relatively large then you will likely run into memory issues. In this case you will need to read the file in chunks. You can decide how many lines to read at a time. Use a for-loop that's set to run for the number of chunks to read (based on the total number of lines and the number of lines you want to read at a time). Hint: Quotient & Remainder function. In the loop use the Read Text File VI to read your set number of lines. Convert the lines to a 2D array delete your column, and write out that chunk of data to the new file. Rinse and repeat.

Delete specified line in a text file

can anyone help me??
how to remove specific line in a text file using java?? thank thanks

Read the file, write a new one, and when you write skip over the line you want to delete.

Delete one row in a text-file

How can i with the JDeveloper delete a row in a ascii
text file ?
I there any way without create a temporary file ?
Can i delete rows from a opened file ?
Is there any suggestion ?
null

Bernd Schlaupitz (guest) wrote:
: How can i with the JDeveloper delete a row in a ascii
: text file ?
: I there any way without create a temporary file ?
: Can i delete rows from a opened file ?
: Is there any suggestion ?
Bernd,
I don't know about a way to do this, My suggestion is to use a
temporary file for this, and then delete the original by
replacing it with the temporary
Federico
null

Deleting a line from a text file & opening a project from another project

hi
im doing project on linux redhat 8.0 using java (jbuilder 8). I need to
open a project2 from behind a menu item in project1. I tried importing
the package of project2 and then initializing a constructor of main
class of project2 in project1(behind the "open project2" menu item) but
i dont know where to place the class files of project2 so im getting a
compilation error(when compiling project1) that unable to locate
imported package files.
is there any other way of doing this
like making an .exe file of project2??? if so, then pls tell me how.
Another problem is i want to delete a line of selected text from a text
file
using java. is there a method for that or any other way?
Anybodyyyy have any ideasss?
Alisha

Cross- and double-posted: http://forum.java.sun.com/thread.jspa?threadID=645244

How to get current month from filename and bulk insert from text file into table?

I set up some dynamic SQL to help my bulk copy data from a text file to a table. This works fine for files that come in every day; I get the previous day’s data, based on the file name that’s placed
in the folder. That’s why I’m using the ‘-1’. The dates will look like this: '20140131', so I'm using type 112.
declare @fullpath1 varchar(1000)
select @fullpath1 = '''\\system.local\ms\london\FTP\' + convert(varchar, getdate()-1, 112) + '_INDEXPRICES_EOM.SPC'''
declare @cmd1 nvarchar(1000)
print (@cmd1)
select @cmd1 = 'bulk insert [dbo].[SB_Monthly] from ' + @fullpath1 + ' with (FIELDTERMINATOR = ''\t'', FIRSTROW = 5, LASTROW = 675, ROWTERMINATOR=''0x0a'')'
print(@cmd1)
exec (@cmd1)
I think the syntax will be somewhat similar to this:
YEAR(date_column)=YEAR(getdate()) AND MONTH(date_column)=MONTH(getdate())
I’m not totally sure how to incorporate that into my current syntax.
Knowledge is the only thing that I can give you, and still retain, and we are both better off for it.

I tried a couple versions of this.
Declare @StartDate Date, @EndDate Date
Select @StartDate = convert(varchar, getdate()-28, 112), @EndDate = convert(varchar, getdate()-1, 112)
BEGIN
declare @fullpath1 varchar(1000)
select @fullpath1 = '''\\ms\london\FTP\' + ''' between ''' + Convert(Varchar(10), @StartDate, 101) + ''' and ''' + Convert(Varchar(10), @EndDate, 101) + '''_SP.SPC'''
declare @cmd1 nvarchar(1000)
print (@cmd1)
select @cmd1 = 'bulk insert [dbo].[SPBMI_Monthly] from ' + @fullpath1 + ' with (FIELDTERMINATOR = ''\t'', FIRSTROW = 5, LASTROW = 675, ROWTERMINATOR=''0x0a'')'
print(@cmd1)
exec (@cmd1)
END
Here’s the string:
bulk insert [dbo].[SPBMI_Monthly] from '\\ms\london\FTP\' between '02/03/2014' and '03/02/2014'_SP.SPC' with (FIELDTERMINATOR = '\t', FIRSTROW = 5, LASTROW = 675, ROWTERMINATOR='0x0a')
The error message I keep getting is:
Msg 156, Level 15, State 1, Line 1
Incorrect syntax near the keyword 'between'.
Msg 319, Level 15, State 1, Line 1
Incorrect syntax near the keyword 'with'. If this statement is a common table expression, an xmlnamespaces clause or a change tracking context clause, the previous statement must be terminated with a semicolon.
I feel like I’m already pushing this thing to the limit.
Maybe this last part isn’t possible.
Knowledge is the only thing that I can give you, and still retain, and we are both better off for it.

HOW TO WRITE AND READ FROM A TEXT FILE???

How can I read from a text file and then display the contents in a JTextArea??????
Also how can I write the contents of a JTextArea to a text file.
Extra Question::::::: Is it possible to write records to a text file. If you have not idea what I am talking about then ignore it.
Manny thanks,
your help is much appreciated though you don't know it!

Do 3 things.
-- Look through the API at the java.io package.
-- Search previous posts for "read write from text file"
-- Search java.sun.com for information on the java.io package.
That should clear just about everything up. If you have more specific problems, feel free to come back and post them.

Reading and Writing to a Text File

Hello all,
I was wondering if it is possible to write from forms to a text file and if possible what is the best way to do it.
Thanks,
Bucky

Use the TEXT_IO built-in functionality in forms or from the database utl_file. TEXT_IO seems to be more flexible because you can read and write to any server/directory you have access to whereas UTL_FILE is limited to the server where the database is located. Hope this helps.
Mike

Reading strings and integers from a text file

I want to read the contents of a text file and print them to screen, but am having problems reading integers. The file contains employee's personal info and basically looks like this:
Warren Laing
32 //age, data type is int
M //gender, data type is String
Sharon Smith
44
F
Here's what I've done so far. The method should continue reading the file until there's no lines left. When I call it from main, I get a numberFormatException error. I'm not sure why because the data types of the set and get methods are correct, the right packages have been imported, and I'm sure I've used Integer.parseInt() correctly (if not, pls let me know). Can anyone suggest why I'm getting errors, or where my code is going wrong?
many thanks
Chris
public void readFile() throws IOException{
BufferedReader read = new BufferedReader(new FileReader("personal.txt"));
int age = 0;
String input = "";
input = read.readLine();
while (input != null){
setName(input);
age = Integer.parseInt(input);
setAge(age);
input = read.readLine();
setGender(input);
System.out.println("Name: " + getName() + " Age: " + getAge() + " Gender: " + getGender());
read.close();

To answer your question - I'm teaching myself java and I haven't covered enumeration classes yet.
With the setGender("Q") scenario, the data in the text file has already been validated by other methods before being written to the file. Anyway I worked out my problems were caused by "input = read.readLine()" being in the wrong places. The code below works fine though I've left out the set and get methods for the time being.
Chris
public static void readFile()throws IOException{
String name = "";
String gender = "";
int age = 0;
BufferedReader read = new BufferedReader(new FileReader("myfile.txt"));
String input = read.readLine();
while(input != null){
name = input;
input = read.readLine();
gender = input;
input = read.readLine();
age = Integer.parseInt(input);
input = read.readLine();
System.out.println("Name: " + name + " Gender: " + gender + " Age: " + age);
read.close();

Reading and Writing from a text file at the same time

I know who to use the Scanner and PrintWriter to read from and write to a .txt file. But these are limited. How can I read and write at the same time? Such as open a file and change every third character or change every second word to something else and then write it back. I found this [http://java.sun.com/docs/books/tutorial/essential/io/|http://java.sun.com/docs/books/tutorial/essential/io/] but its a little over my head. Is this the only way to do it?

wrote:
You are using buffered reads and writes I would assume, right? Also, how do you think most programs handle this sort of thing? I don't believe I'm using buffering.
My code looks something like this
//...necessary imports
//then
Scanner inFile = new Scanner (new file("filename1.txt"));
PrintWriter outFile = new PrintWriter ("filename2.txt");
//then stuff like
int x = inFile.hasNextInt();
outFile.println(x);
camickr wrote:If you are changing the data "in place", that is none of the data in the file is shifted, then you can use a RandomAccessFile.
Otherwise, you've been given the answer above.What is RandomAccessFile? Is it what I have a link to? Basically what I do is I write a bunch of numbers to a txt file and then change the numbers I don't need anymore to 0. So say I had 0 1 2 3 4 5 6 7 etc. I would like to to open the txt file and change every second one to 0 so then I'd have only odd numbers and 0s.
I looked at the documentation for RandomAccessFile and it seems like it might be what I need.
Thankyou both for your help so far. I took a java course in high school and they only taught me one way to get data from text files and that is what I just showed you. So maybe this questions are really stupid. lol
Edited by: qw3n on Jun 13, 2009 7:46 PM

Adding And Removing in a text file

Hi
I'm trying to make a VI that generates a textfile which saves some data each second and give it some timeframe so that it can maintain only the data that has been generated last 10 seconds or so
First I have made 2 different files, one is for saving some data each second into a text file, and the other one is for removing the data
but when i combined those two it doesn't seem to work.
Could anyone have a look at the file and comment on that?
thanks
Attachments:
test2.vi ‏17 KB
Time(Sub).vi ‏8 KB

A couple comments on what you are trying to do. First, doing this with a text file is going to be inherently difficult as you are going to be doing a lot of rewriting of the file. Second, having two VIs (1 to write the data and 1 to remove the old data) is a bad approach - why not design the algorithm so the file is only written to one time for each update cycle? Stop trying to make a poor design work and spend a little time thinking outside the box.
Hint: think about how you calculate a running average in LV, and what if the indicator out wasn't just an indicator but a file write?
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

Delete and reaname oprations on text files??

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