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.
Similar Messages
-
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?
AlishaCross- and double-posted: http://forum.java.sun.com/thread.jspa?threadID=645244
-
Read specified line from a text file
Hi,
I am trying to read a specific line from a text file. I don't want to read all of it but just this specific line... say line number 2. Is there a method built-in in java or should I code this myself?
Thanks and regards,
Krt_MaltaKrt_malta wrote:
I am trying to read a specific line from a text file. I don't want to read all of it but just this specific line... say line number 2. Is there a method built-in in java or should I code this myself?Is there anything in your use case that precludes using the offset of the start of the line rather than the line number? -
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 KannanBufferedReader 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 -
i need to delete (or replace them with white space) a few lines from a text file. I have a text file with first few lines & last few lines containing "<"or ">". I need to delete/replace with white space, the entire line. i need to do this urgently
Could some one please tell me how to do this?the file can be of size 8MB or more. i get this file
every week from a third party. So the size is not
constant. I need to remove/replace with white space,
the fist & last few lines and the rest is comma
seperated values which i need to load to database
using sqlldr. But still not sure abt how to remove
the first few lines.
i need to read this file, replace the lines as i read
them and write the replaced string back to the file &
then load the rest of lines to database.8 MByte is fairly small. Read the file a line at a time and copy to a new file only the lines you want. Should take no more than a second or so.
P.S. It will probably be a mistake if you try to edit the original file in place. -
Delete or update a line in a text file
Hi, I've got one problem and I hope anybody can help me.
I read a text file like this :
montext = 20204578
montext2 = 22132546
montext3 = 31321321
I want to know how I can delete or update a specific line in my text file.
thanks a lot.I read a text file like this :
montext = 20204578
montext2 = 22132546
montext3 = 31321321
I want to know how I can delete or update a specific
line in my text file.Sure. read in the file with the Readers readLine()-method in a loop; if the line it read is the one that should be removed, don't add it (or use a counter variable, if you do it by numbers) to the output String.
If it's to be replaced, replace it at that moment, then add the new line to the string.
Write back the string into the old file (don't append) and you're done.
Answer provided by Friends of the Water Cooler. Please tell forum admin via 'Discuss the JDC Web Site' forum that off-topic threads should be supported
Thanks, Geoff, good idea! -
How to read some lines from a text file using java.
hi,
i m new to java and i want to read some lines from a text file based on some string occurrence in the file. This file to be read in steps.
we only want to read the file upto the first Occurrence of "TEXT" string.
How to do it ,,,
Kinldy give the code
Regards,
Sagar
this is the text file
dfgjdjj
sfjhjkd
ghjkdg
hjkdgh TEXT
ikeyt
ujt
jk
tyk TEXT
rukl
rHendawy wrote:
Since the word "TEXT" is formed of 4 letters, you would read the text file 4 bytes by four bytes. Wrong on two counts. First, the file may not be encoded 1 byte per character. It could be utf-16 in which case it would be two byte per character. Second, even if it were 1 byte per character, the string "Text" may not start on a 4 byte boundary.
Consider a FileInputStream object "fis" that points to your text file. use fis.read(byte[] array, int offset, int len) to read every four bytes. Convert the "TEXT" String into a byte array "TEXT".getBytes(), and yous the Arrays class to compare the equality of the read bytes with your "TEXT".getBytes()Wrong since it relies on my second point and will fail when fis.read(byte[] array, int offset, int len) does not read 4 bytes (as is no guaranteed to). Check the Javadoc. Also, the file may not be encoded with the default character encoding.
The problem is easily solved by reading a line at a time using a BufferedReader wrapping an InputStreamReader wrapping a FileInputStream and specifying the correct character encoding.
Edited by: sabre150 on Apr 29, 2009 2:13 PM -
Reading a Random Line from a Text File
Hello,
I have a program that reads from a text file words. I currently have a text file around 800KB of words. The problem is, if I try to load this into an arraylist so I can use it in my application, it takes wayy long to load. I was wondering if there was a way to just read a random line from the text file.
Here is my code, and the text file that the program reads from is called 'wordFile'
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
public class WordColor extends JFrame{
public WordColor(){
super("WordColor");
setSize(1000,500);
setVisible(true);
add(new WordPanel());
public static void main(String[]r){
JFrame f = new WordColor();
class WordPanel extends JPanel implements KeyListener{
private Graphics2D pane;
private Image img;
private char[]characterList;
private CharacterPosition[]positions;
private int charcounter = 0;
private String initialWord;
private File wordFile = new File("C:\\Documents and Settings\\My Documents\\Java\\projects\\WordColorWords.txt");
private FontMetrics fm;
private javax.swing.Timer timer;
public final static int START = 20;
public final static int delay = 10;
public final static int BOTTOMLINE = 375;
public final static int buffer = 15;
public final static int distance = 4;
public final static Color[] colors = new Color[]{Color.red,Color.blue,Color.green,Color.yellow,Color.cyan,
Color.magenta,Color.orange,Color.pink};
public static String[] words;
public static int descent;
public static int YAXIS = 75;
public static int SIZE = 72;
public WordPanel(){
words = readWords();
setLayout(new BorderLayout());
initialWord = getWord();
characterList = new char[initialWord.length()];
for (int i=0; i<initialWord.length();i++){
characterList[i] = initialWord.charAt(i);
setFocusable(true);
addKeyListener(this);
timer = new javax.swing.Timer(delay,new ActionListener(){
public void actionPerformed(ActionEvent evt){
YAXIS += 1;
drawWords();
if (YAXIS + descent - buffer >= BOTTOMLINE) lose();
if (allColorsOn()) win();
public void paintComponent(Graphics g){
super.paintComponent(g);
if (img == null){
img = createImage(getWidth(),getHeight());
pane = (Graphics2D)img.getGraphics();
pane.setColor(Color.white);
pane.fillRect(0,0,getWidth(),getHeight());
pane.setFont(new Font("Arial",Font.BOLD,SIZE));
pane.setColor(Color.black);
drawThickLine(pane,getWidth(),5);
fm = g.getFontMetrics(new Font("Arial",Font.BOLD,SIZE));
descent = fm.getDescent();
distributePositions();
drawWords();
timer.start();
g.drawImage(img,0,0,this);
private void distributePositions(){
int xaxis = START;
positions = new CharacterPosition[characterList.length];
int counter = 0;
for (char c: characterList){
CharacterPosition cp = new CharacterPosition(c,xaxis, Color.black);
positions[counter] = cp;
counter++;
xaxis += fm.charWidth(c)+distance;
private void drawThickLine(Graphics2D pane, int width, int thickness){
pane.setColor(Color.black);
for (int j = BOTTOMLINE;j<BOTTOMLINE+1+thickness;j++){
pane.drawLine(0,j,width,j);
private void drawWords(){
pane.setColor(Color.white);
pane.fillRect(0,0,getWidth(),getHeight());
drawThickLine(pane,getWidth(),5);
for (CharacterPosition cp: positions){
int x = cp.getX();
char print = cp.getChar();
pane.setColor(cp.getColor());
pane.drawString(""+print,x,YAXIS);
repaint();
private boolean allColorsOn(){
for (CharacterPosition cp: positions){
if (cp.getColor() == Color.black) return false;
return true;
private Color randomColor(){
int rand = (int)(Math.random()*colors.length);
return colors[rand];
private void restart(){
charcounter = 0;
for (CharacterPosition cp: positions){
cp.setColor(Color.black);
private void win(){
timer.stop();
newWord();
private void newWord(){
pane.setColor(Color.white);
pane.fillRect(0,0,getWidth(),getHeight());
repaint();
drawThickLine(pane,getWidth(),5);
YAXIS = 75;
initialWord = getWord();
characterList = new char[initialWord.length()];
for (int i=0; i<initialWord.length();i++){
characterList[i] = initialWord.charAt(i);
distributePositions();
charcounter = 0;
drawWords();
timer.start();
private void lose(){
timer.stop();
pane.setColor(Color.white);
pane.fillRect(0,0,getWidth(),getHeight());
pane.setColor(Color.red);
pane.drawString("Sorry, You Lose!",50,150);
repaint();
removeKeyListener(this);
final JPanel p1 = new JPanel();
JButton again = new JButton("Play Again?");
p1.add(again);
add(p1,"South");
p1.setBackground(Color.white);
validate();
again.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent evt){
remove(p1);
addKeyListener(WordPanel.this);
newWord();
private String getWord(){
int rand = (int)(Math.random()*words.length);
return words[rand];
private String[] readWords(){
ArrayList<String> arr = new ArrayList<String>();
try{
BufferedReader buff = new BufferedReader(new FileReader(wordFile));
try{
String line = null;
while (( line = buff.readLine()) != null){
line = line.toUpperCase();
arr.add(line);
finally{
buff.close();
catch(Exception e){e.printStackTrace();}
Object[] objects = arr.toArray();
String[] words = new String[objects.length];
int count = 0;
for (Object o: objects){
words[count] = (String)o;
count++;
return words;
public void keyPressed(KeyEvent evt){
char tempchar = evt.getKeyChar();
String character = ""+tempchar;
if (character.equalsIgnoreCase(""+positions[charcounter].getChar())){
positions[charcounter].setColor(randomColor());
charcounter++;
else if (evt.isShiftDown()){
evt.consume();
else{
restart();
drawWords();
public void keyTyped(KeyEvent evt){}
public void keyReleased(KeyEvent evt){}
class CharacterPosition{
private int xaxis;
private char character;
private Color color;
public CharacterPosition(char c, int x, Color col){
xaxis = x;
character = c;
color = col;
public int getX(){
return xaxis;
public char getChar(){
return character;
public Color getColor(){
return color;
public void setColor(Color c){
color = c;
}I thought that maybe serializing the ArrayList might be faster than creating the ArrayList by iterating over each line in the text file. But alas, I was wrong. Here's my code anyway:
class WordList extends ArrayList<String>{
long updated;
WordList readWordList(File file) throws Exception{
WordList list = new WordList();
BufferedReader in = new BufferedReader(new FileReader(file));
String line = null;
while ((line = in.readLine()) != null){
list.add(line);
in.close();
list.updated = file.lastModified();
return list;
WordList wordList;
File datFile = new File("words.dat");
File txtFile = new File("input.txt");
if (datFile.exists()){
ObjectInputStream input = new ObjectInputStream(new FileInputStream(datFile));
wordList = (WordList)input.readObject();
if (wordList.updated < txtFile.lastModified()){
//if the text file has been updated, re-read it
wordList = readWordList(txtFile);
ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream(datFile));
output.writeObject(wordList);
output.close();
} else {
//serialized list does not exist--create it
wordList = readWordList(txtFile);
ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream(datFile));
output.writeObject(wordList);
output.close();
}The text file contained one random sequence of letters per line. For example:
hwnuu
nhpgaucah
zfbylzt
hwnc
gicgwkhStats:
Text file size: 892K
Serialized file size: 1.1MB
Time to read from text file: 795ms
Time to read from serialized file: 1216ms -
CLIENT_TEXT_IO : cannot insert new line into a text file
Facts:
Developer 10g
AS 10g
Web utility
Problem:
i am traying to
Open a text file. using CLIENT_TEXT_IO.FOPEN
insert a record in to a text file using CLIENT_TEXT_IO.PUTF
insert a new line using chr(10) or CLIENT_TEXT_IO.NEW_LINE
or CLIENT_TEXT_IO.put_line
insert the next record
Close the file.
all work except insert a new line
Why !!!
it was Working fine in 6i, but now in 10g and Webutil is not working
plz helpHi you can put a new line in a text file using System.getProperty("line.separator"). This implementation will work for every OS.
import java.io.*;
class Demo{
public static void main(String args[]) throws Exception {
FileWriter fr = new FileWriter("FileDemo.txt");
fr.write("AAAAAAAAAA");
fr.write(System.getProperty("line.separator"));
fr.write("AAAAAAAAAAA");
fr.close();
} -
Reading one line from a text file into an array
i want to read one line from a text file into an array, and then the next line into a different array. both arays are type string...i have this:
public static void readAndProcessData(FileInputStream stream){
InputStreamReader iStrReader = new InputStreamReader (stream);
BufferedReader reader = new BufferedReader (iStrReader);
String line = "";
try{
int i = 0;
while (line != null){
names[i] = reader.readLine();
score[i] = reader.readLine();
line = reader.readLine();
i++;
}catch (IOException e){
System.out.println("Error in file access");
this section calls it:
try{
FileInputStream stream = new FileInputStream("ISU.txt");
HighScore.readAndProcessData(stream);
stream.close();
names = HighScore.getNames();
scores = HighScore.getScores();
}catch(IOException e){
System.out.println("Error in accessing file." + e.toString());
it gives me an array index out of bounds erroroh wait I see it when I looked at the original quote.
They array you made called names or the other one is prob too small for the amount of names that you have in the file. Hence as I increases it eventually goes out of bounds of the array so you should probably resize the array if that happens. -
Best way to remove last line-feed in text file
What is the best way to remove last line-feed in text file? (so that the last line of text is the last line, not a line-feed). The best I can come up with is: echo -n "$(cat file.txt)" > newfile.txt
(as echo -n will remove all trailing newline characters)What is the best way to remove last line-feed in text file? (so that the last line of text is the last line, not a line-feed). The best I can come up with is: echo -n "$(cat file.txt)" > newfile.txt
(as echo -n will remove all trailing newline characters)
According to my experiments, you have removed all line terminators from the file, and replaced those between lines with a space.
That is to say, you have turned a multi-line file into one long line with no line terminator.
If that is what you want, and your files are not very big, then your echo statement might be all you need.
If you need to deal with larger files, you could try using the 'tr' command, and something like
tr '
' ' ' <file.txt >newfile.txt
The only problem with this is, it will most likely give you a trailing space, as the last newline is going to be converted to a space. If that is not acceptable, then something else will have to be arranged.
However, if you really want to maintain a multi-line file, but remove just the very last line terminator, that gets a bit more complicated. This might work for you:
perl -ne '
chomp;
print "
" if $n++ != 0;
print;
' file.txt >newfile.txt
You can use cat -e to see which lines have newlines, and you should see that the last line does not have a newline, but all the others still do.
I guess if you really did mean to remove all newline characters and replace them with a space, except for the last line, then a modification of the above perl script would do that:
perl -ne '
chomp;
print " " if $n++ != 0;
print;
' file.txt >newfile.txt
Am I even close to understanding what you are asking for? -
Random Line reading in text file
I am trying to read a random line in a text file but every time i read it it reads first line of the file any one can help me what is the problem in the code is or provide me with a new code.
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
File file = new File("word.txt");
if(!file.exists())
System.out.println("File does not exist.");
System.exit(0);
try{
//Open the file for reading
RandomAccessFile raf = new RandomAccessFile(file, "r");
raf.seek(file.length()); //Seek to end of file
System.out.println("Read full line: " + raf.readLine());
//str2 is a String
str2 = str2 + raf.readLine();
System.out.println(""+str2);
raf.close();
System.out.println("Successfully");
catch(IOException ioe)
System.out.println(ioe.getMessage());
my text file look like in this format
mind
hate
Abhor
Bigot
narrow
prejudiced
person
Counterfeit
fake
false
give
voting
rights
Hamper
hinder
obstruct
Kindle
to
start
fire
harmful
poisonous
lethalNext time when posting code, please use code tags: http://forum.java.sun.com/help.jspa?sec=formatting
A RandomAccessFile has nothing to do with getting a (pseudo) random line number from a file.
You should also split things up in separate methods:
- a method for counting the number of lines in a file;
- a method to get the N-th line from a file.
In your main method, you call the method which counts the number of lines N in a file and then generate a (pseudo) random number between 1 and N. Use the java.util.Random class for this.
When you have generated that number, call the other method to get that specific line number.
Here's a small start:
import java.io.*;
import java.util.*;
public class Main {
public static String getLineNumber(int number) throws FileNotFoundException {
// your code here
public static int countLines(String fileName) throws FileNotFoundException {
// your code here
public static void main(String[] args) throws Exception {
int numberLines = countLines("word.txt");
Random generator = new Random();
int randomNumber = generator.nextInt(numberLines)+1;
String randomLine = getLineNumber(randomNumber);
System.out.println("Line "+randomNumber+" = '"+randomLine+"'");
}In both methods, you can use the java.util.Scanner class to read lines from the file.
Have a look at the API docs of the Scanner class:
http://java.sun.com/j2se/1.5.0/docs/api/java/util/Scanner.html (including code samples!)
Good luck. -
File adapter-How to set line break in text file-split record into two lines
Dear Guru's,
I have to solve following problem with XML (with mulitiple records) to TEXT file scenario using file adapter. I have to output for ever ONE data record in XML always two identical lines in text file. Second line should have a little bit different mapping in few fields like date,... So I did duplicate fileds in my output structure in mapping and need to know how to set line break in the middle and see half of structure in first line and next structure half in second line
My output structure in mapping is:
CASHFLOW
- INTERFACE
- GESELLSCHAFT
- ANWENDUNG
- PRODUKT
- VERTRAG
- BETRAG
- WAEHRUNG
- DIRECTION
- BEWEGUNGSTYP
- FAELLIGKEIT
- ZINSFESTSTELLUNG
- ZAHLUNGSTAG
- RENDITE
- INTERFACE2
- GESELLSCHAFT2
- ANWENDUNG2
- PRODUKT2
- VERTRAG2
- BETRAG2
- WAEHRUNG2
- DIRECTION2
- BEWEGUNGSTYP2
- FAELLIGKEIT2
- ZINSFESTSTELLUNG2
- ZAHLUNGSTAG2
- RENDITE2
Question is how can I set on receiving file adapter in Content Conversion Parameters that fields from first structure half INTERFACE...RENDITE should be outputed in one line and fields from second half of structure INTERFACE2...RENDITE2 should start on second line in final text file.
I'm getting at the moment one line only and I need to know how can set line break so that second line starting with INTERFACE2(CA)...RENDITE2 will start in new line.
CA,"0100","7","512",20090127010001,-12454762586.6800,"EUR",2,12,2009-01-28,2009-01-27,2009-01-28,"0.0000000",CA,"0100","7","512",20090127010001,-12454762586.6800,"EUR",1,10,2009-01-27,2009-01-27,2009-01-27,"0.0000000"
This should be final output:
CA,"0100","7","512",20090127010001,-12454762586.6800,"EUR",2,12,2009-01-28,2009-01-27,2009-01-28,"0.0000000"
CA,"0100","7","512",20090127010001,-12454762586.6800,"EUR",1,10,2009-01-27,2009-01-27,2009-01-27,"0.0000000"
My file adapter settings:
RecordsetStructure=CASHFLOW
CASHFLOW.fieldNames=INTERFACE,GESELLSCHAFT,ANWENDUNG,PRODUKT,VERTRAG,BETRAG,WAEHRUNG,DIRECTION,BEWEGUNGSTYP,FAELLIGKEIT,ZINSFESTSTELLUNG,ZAHLUNGSTAG,RENDITE
CASHFLOW.fieldSeparator=,
CASHFLOW.endSeparator='nl'
CASHFLOW.fieldNames=INTERFACE2,GESELLSCHAFT2,ANWENDUNG2,PRODUKT2,VERTRAG2,BETRAG2,WAEHRUNG2,DIRECTION2,BEWEGUNGSTYP2,FAELLIGKEIT2,ZINSFESTSTELLUNG2,ZAHLUNGSTAG2,RENDITE2
CASHFLOW.fieldSeparator=,
It wont help if I add two identical structures in mapping because in output i would see for multiple entries section with first lines only and after that section with second lines only. And CASHFLOW is one part of more complex mapping ...
(This is final output structure RecordsetStructure=HEADER,CASHFLOW,CONDITION,REFERENCE,CONTRACT - more sections with different data and all these should have duplicate lines at the end)
Thanks a lot for any help
Cheers
Marian
Edited by: Marian Luscon on Jul 14, 2009 11:44 AMHi Ivan,
right, I did test just for sure.
Putting constant 'nl' into field CASHFLOW-INTERFACE1 didnt help - still getting one line instead two lines.
CA ,"0100" ,"7" ,"512" ,20090127GTP101 ,-12454762586.6800 ,"EUR" ,2 ,12 ,2009-01-28 ,2009-01-27 ,2009-01-28 ,"0.0000000" ,'nl' ,"GTP1" ,"7" ,"512" ,20090127GTP101 ,-12454762586.6800 ,"EUR" ,1 ,10 ,2009-01-27 ,2009-01-27 ,2009-01-27 ,"0.0000000"
So there is still question. Is there any way (mapping,...) how to output always 2 lines in text file for one record in XML. It always does 1 record in mapping structure = 1 line but we need 2 lines ...
Example:
Input: 4 records in XML
Output: 8 lines in final text file ...
Thanks to you all guys
Marian -
Change of a single line in a text file
Is there a option in CVI to change a single line in a text file (.txt), without reading the whole text file into the buffer and writing the whole buffer back after the editing from the one line?
Not that I am aware of.
I'll be glad to know such a function if somebody can point us to it!
Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos? -
How to insert new line in a text file
hi all,
i wnat to know how can i insert a new line in a text file using java.
for example i want the formate of the text like this
1 2 3
4 5 6
until now i know only how to insert data but not new line.
Thanks in advandceHi you can put a new line in a text file using System.getProperty("line.separator"). This implementation will work for every OS.
import java.io.*;
class Demo{
public static void main(String args[]) throws Exception {
FileWriter fr = new FileWriter("FileDemo.txt");
fr.write("AAAAAAAAAA");
fr.write(System.getProperty("line.separator"));
fr.write("AAAAAAAAAAA");
fr.close();
}
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