Reading the same line twice from a file
I have code which I have to read the same line of a file when I want. Reading the file by line line to an arraylist or a variable is not the thing that I want. I just want to mark a line position in a file and read to start from the position. Random Files uses seek to do this, but I have to convert bytes and parse them into lines.
Does bufferedreader has some property or another reading method support this?
mark() and reset() ?
Read the API docs for a change http://java.sun.com/javase/6/docs/api/java/io/BufferedReader.html
Similar Messages
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How to read the last line in a txt file?
Dear all,
I want to read the last line in a txt file. There are thousands of lines in this file. What I want is to move the file pointer directly to the last line of the file. But I did not know how do to it. Can anybody help me out?
Thank you very much!If the file is coded as ASCII or one of the encodings that maps a single byte to a char then the following class will assist you
import java.io.*;
import java.util.*;
public class GetLinesFromEndOfFile
static public class BackwardsFileInputStream extends InputStream
public BackwardsFileInputStream(File file) throws IOException
assert (file != null) && file.exists() && file.isFile() && file.canRead();
raf = new RandomAccessFile(file, "r");
currentPositionInFile = raf.length();
currentPositionInBuffer = 0;
public int read() throws IOException
if (currentPositionInFile <= 0)
return -1;
if (--currentPositionInBuffer < 0)
currentPositionInBuffer = buffer.length;
long startOfBlock = currentPositionInFile - buffer.length;
if (startOfBlock < 0)
currentPositionInBuffer = buffer.length + (int)startOfBlock;
startOfBlock = 0;
raf.seek(startOfBlock);
raf.readFully(buffer, 0, currentPositionInBuffer);
return read();
currentPositionInFile--;
return buffer[currentPositionInBuffer];
public void close() throws IOException
raf.close();
private final byte[] buffer = new byte[4096];
private final RandomAccessFile raf;
private long currentPositionInFile;
private int currentPositionInBuffer;
public static List<String> head(File file, int numberOfLinesToRead) throws IOException
return head(file, "ISO-8859-1" , numberOfLinesToRead);
public static List<String> head(File file, String encoding, int numberOfLinesToRead) throws IOException
assert (file != null) && file.exists() && file.isFile() && file.canRead();
assert numberOfLinesToRead > 0;
assert encoding != null;
LinkedList<String> lines = new LinkedList<String>();
BufferedReader reader= new BufferedReader(new InputStreamReader(new FileInputStream(file), encoding));
for (String line = null; (numberOfLinesToRead-- > 0) && (line = reader.readLine()) != null;)
lines.addLast(line);
reader.close();
return lines;
public static List<String> tail(File file, int numberOfLinesToRead) throws IOException
return tail(file, "ISO-8859-1" , numberOfLinesToRead);
public static List<String> tail(File file, String encoding, int numberOfLinesToRead) throws IOException
assert (file != null) && file.exists() && file.isFile() && file.canRead();
assert numberOfLinesToRead > 0;
assert (encoding != null) && encoding.matches("(?i)(iso-8859|ascii|us-ascii).*");
LinkedList<String> lines = new LinkedList<String>();
BufferedReader reader= new BufferedReader(new InputStreamReader(new BackwardsFileInputStream(file), encoding));
for (String line = null; (numberOfLinesToRead-- > 0) && (line = reader.readLine()) != null;)
// Reverse the order of the characters in the string
char[] chars = line.toCharArray();
for (int j = 0, k = chars.length - 1; j < k ; j++, k--)
char temp = chars[j];
chars[j] = chars[k];
chars[k]= temp;
lines.addFirst(new String(chars));
reader.close();
return lines;
public static void main(String[] args)
try
File file = new File("/usr/share/dict/words");
int n = 10;
System.out.println("Head of " + file);
int index = 0;
for (String line : head(file, n))
System.out.println(++index + "\t[" + line + "]");
System.out.println("Tail of " + file);
int index = 0;
for (String line : tail(file, "us-ascii", n))
System.out.println(++index + "\t[" + line + "]");
catch (Exception e)
e.printStackTrace();
}Note, the EOL characters are treated as line separators so you will probably need to read the last two lines (think about it for a bit). -
How to read the second line in a .txt file with bufferedReader?
hi,
i am not the best in speaking english and programming java :)
so, just try to make sense of my question:
Im using a BufferedReader to read a .txt file.
the .txt file has 5+ different lines, and each line has 6 tokens (separated with ; )
My java file has 6 textFields and each textfield is filled with one of the 6 different tokens.
and my problem is:
I want my buffered reader to read the next line (with 6 new different tokens) by pressing a button.
if somethings not understandable, just ask :)maybe its easier to help me, when i publish my code, so here it is:
(its my version, without Thof's code. Sorry, but the comments are the most in german)
/* userdata.java */
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import javax.swing.*;
import java.util.*;
import java.io.*;
public class userdata extends Frame {
//-----------------------------------KlassenVariablen------------------------------------------------
private JPanel panel = new JPanel ();
String tokId = "";
String tokName= "";
String tokAge= "";
String tokTel= "";
String tokMail= "";
String tokText= "";
BufferedReader br;
String zeile;
StringTokenizer st;
String delim = ";";
//---------Buttons f?r Panel 1-------------------------
Button first = new Button("|< First");
Button back = new Button("< Back");
Button next = new Button("Next >");
Button last = new Button("Last >|");
//---------Buttons f?r Panel 3-------------------------
Button neu = new Button("New");
Button safe = new Button("Safe");
Button refresh = new Button("Refresh");
//--------Labels f?r Panel 2-----------------------------
Label lid = new Label("ID",Label.LEFT);
Label lname = new Label("Name",Label.LEFT);
Label lage = new Label("Age",Label.LEFT);
Label ltel = new Label("Tel.",Label.LEFT);
Label lmail = new Label("E-Mail",Label.LEFT);
Label ltext = new Label("Spruch",Label.LEFT);
Label lub = new Label("Last Button",Label.LEFT);
TextField id = new TextField();
TextField name = new TextField();
TextField age = new TextField();
TextField tel = new TextField();
TextField mail = new TextField();
TextField text = new TextField();
TextField usedbutton = new TextField();
//--------ActionEvent bla sachen eben--------------------
public static void main (String[] args) throws IOException {
userdata wnd = new userdata();
wnd.setVisible(true);
public userdata() throws IOException {
//--------------------------------Layout mit panel bestimmung--------------------------------------
setLayout(new BorderLayout());
JPanel p1 = new JPanel();
JPanel p2 = new JPanel();
JPanel p3 = new JPanel();
add(BorderLayout.NORTH ,p1);
add(BorderLayout.CENTER , p2);
add(BorderLayout.SOUTH , p3);
//-------------------------------Funktionslose Buttons in PANEL 1------------------------------------
p1.add(first);
p1.add(back);
p1.add(next);
p1.add(last);
p1.add(usedbutton);
//--------------------------------Funktionierende Textfelder in PANEL 2------------------------------
Panel labelpanel = new Panel();
p2.setLayout(new GridLayout(7,3));
p2.add(lid);
p2.add(id);
p2.add(lname);
p2.add(name);
p2.add(lage);
p2.add(age);
p2.add(ltel);
p2.add(tel);
p2.add(lmail);
p2.add(mail);
p2.add(ltext);
p2.add(text);
p2.add(lub);
p2.add(usedbutton);
//--------------------------------------Buttons in PANEL 3-----------------------------------------
p3.add(neu);
p3.add(safe);
p3.add(refresh);
//--------------------------------BufferedReader -------------------------------------------------
readData();
//--------------------------------Panel 2 TextField-----------------------------------------------
fillForm();
//================================ActionPerformed==================================================
first.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.out.println ("First");
usedbutton.setText("First");
back.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.out.println ("Back");
usedbutton.setText("Back");
next.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.out.println ("Next");
usedbutton.setText("Next");
last.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.out.println ("Last");
usedbutton.setText("Last");
neu.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.out.println ("New entry");
usedbutton.setText("New");
safe.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.out.println ("Now Saving, do not turn off!");
usedbutton.setText("Save");
//-----------------refresh
refresh.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed( ActionEvent e ) {
try{
readData();
}catch( IOException ioe){
System.out.println("Fehler beim lesen aus Datei");
fillForm();
usedbutton.setText("Refresh");
//=============================================================================Button Funktionen!!!
pack();
//--------------------------------WindowsListener hinzuf?gene--------------------------------------
addWindowListener(
new WindowAdapter() {
public void windowClosing(WindowEvent event)
setVisible(false);
dispose();
System.exit(0);
//-----------------------------------readData() - > Buffered Reader in aktion! --------------------
private void readData() throws IOException{
BufferedReader br = new BufferedReader(new FileReader("My .txt File with path"));
String zeile;
StringTokenizer st;
String delim = ";";
zeile = br.readLine();
st = new StringTokenizer(zeile, delim);
st.hasMoreTokens();
//System.out.println (st.nextToken());
tokId = new String(st.nextToken());
tokName = new String (st.nextToken());
tokAge = new String (st.nextToken());
tokTel = new String (st.nextToken());
tokMail = new String (st.nextToken());
tokText = new String (st.nextToken());
//--------------------------fillForm() - > f?llt die TextFelder aus!--------------------------------
private void fillForm(){
id.setText(tokId);
name.setText(tokName);
age.setText(tokAge);
tel.setText(tokTel);
mail.setText(tokMail);
text.setText(tokText);
} -
How to read the last line in a text file using text_io?? please help
Dear all
I made a procedure that append text into a text file on the operating system.
the text file grows rapidly. It contains now about 200,000 line . I need to read the last line only . In other wprds i need to go direct to the last line to read some values. Is it possible??
Please helpHello,
If you know the number of the line you want to read, I can sugget you to use the MORE dos command or the TAIL unix command that redirect to a temporary text file
Example to create a file that contains the 200010th last lines :
(Client)Host( 'MORE the_file_name.txt +200010 > small_file.txt') ;So you have only to read the small file with the TEXT_IO functions.
Francois -
Reading the BR*Tools responses from a file
Hi,
Can we keep all the responses for BRTools in a file & ask BRTools to read from it? We need this to perform the repetitive tasks.
I have tried this. BR*Tools reads first few responses but give error u201CBR0255E Cannot read from standard inputu201D
Can anybody suggest how this can be done?
Regards,
Vivdha> Instead of using commands we want to save all the responses (like continue, back etc. using the standard keys) in a file & execute it through BR*Tools using file redirection technique.
The question is: why? What is your issue with using "one" command instead of a command + a file?
> I am reading the file by executing at the command prompt brtools < <file>
I understand the issue and what you want to do - but again, why do you want to that if there is a much easier way of doing it?
Markuks -
Hi!
I don't now how can I read for example line number 5 of a file, this is the way I do , but it doesn't work. What the programme should do is read the first line and then read line number 5, but it read line number 2!!!
Could someone help me or paste a code ?
This is my code:
file = new File("fich");
try{
fileR = new FileReader(file);
catch(FileNotFoundException e){}
BufferedReader bfr = new BufferedReader(fileR);
LineNumberReader lnr = new LineNumberReader(bfr);
String line=null;
line=lnr.readLine();
System.out.println("Line number:: " + lnr.getLineNumber());
System.out.println(" ----> " + line);
lnr.setLineNumber(5);
System.out.println("Line number:: " + lnr.getLineNumber());
line=lnr.readLine();
System.out.println("Line number:: " + lnr.getLineNumber());
System.out.println(" ----> " + line);
Thanks
AndreiaI was looking through the bug reports (see 4178689) and this is what I found in the answer:
"The line number kept in LineNumberReader is not the same as the physical line
number in the input file. It is just a local counter in the reader. Setting
this number only results in the reader start counting from a new number from
the next readLine(), it does not allow jumping from one line to another in
the physical data file. The readLine() call just read lines one after another
from the underlying stream, unless reset() or skip() is called."
rbelovoskey presented a quick work-around:
public void navigateForwardToLine(LineNumberReader lineNumberReaderIn, int intLineToGoTo)
int intInitialLine = lineNumberReaderIn.getLineNumber();
try{
for( int intCurrentLine = intInitialLine; intCurrentLine < intLineToGoTo; intCurrentLine++)
lineNumberReaderIn.readLine();
}catch(IOException ioe){
ioe.printStackTrace(); -
How to only read the last line in the text file by using BufferedReader ?
Dear all,
Hello, I am new to Java. Do anybody know how to read the last line (this is the last record) in the text file.The method I am now using is reading from the first line until I reach the last line in the text file. Thank you!!
BufferedReader br = new BufferedReader(new FileReader("c:\\sdk1.4.1\\bin\\dbExport.txt"));
DataInputStream in = new DataInputStream(new FileInputStream("c:\\sdk1.4.1\\bin\\dbExport.txt"));
String input;
String firstinput;
String secondinput;
int count=90;
int year=1955;
while ((input = br.readLine()) != null) {
firstinput = input.substring(0, 10);
secondinput = input.substring(10);
String insertStore1 = ("INSERT INTO AUTHORS " +
"VALUES ('" + count + "', '" + firstinput + "', '" + secondinput + "', 1955)");
System.out.println(insertStore1);
int result = stmt.executeUpdate(insertStore1);I suppose you could use a java.io.RandomAccessFile.
-
When i watch vids on any website i see the same vid twice. One on top of the other with a green line dividing them
== This happened ==
Every time Firefox opened
== TodayFirst of all, Firefox support SUCKS! I am looking onto Opera or Chrome.
Here is my solution. I have WinXP 64 bit with a Nvidia card. I had the same issue and all I had to do is update the video drivers and it fixed the problem. Try this out. -
About a week ago I started getting phone calls on my cell phone from numbers that do not exist, including the area codes. I can not report these to the Do Not Call list because the area code is non existent. I'm getting these calls all the time now and never from the same number twice so there's no point in blocking them. If I answer I may or may not get a person who has an accent from India so heavy that I can't understand what they are saying. This is getting to the point where I just want to cry I'm so frustrated. Anyone else having this issue or does anyone know how to stop it?
Thank youI'm sorry that you are having all these troubles. I have sent you a private message.
Anthony_VZ
**If someones post has helped you, please acknowledge their assistance by clicking the red thumbs up button to give them Kudos. If you are the original poster and any response gave you your answer, please mark the post that had the answer as the solution**
Notice: Content posted by Verizon employees is meant to be informational and does not supersede or change the Verizon Forums User Guidelines or Terms or Service, or your Customer Agreement Terms and Conditions or plan -
Gif - file help: i don't want to read the gif each time from the file.....
Hello there guys,
i'm making a game and therefor i need to read a gif file like 20 times.
i don't want my program to read the gif each time from the file, but only once.
so i load it into an image or something?
cuz opening the gif 20 times from my hard disk is a lot of time loss....
opening it once and store it is much more efficient
thx in advance
plz help me out, cuz i don't really know how to do it.
(in Delphi it's easy, but Java......)
greetz,
SpeciesXX
Ramon Ribbeyes, it works, i used this code, thx man
void button1_ActionPerformed(java.awt.event.ActionEvent event)
ImageIcon image = new ImageIcon("f:/a.gif");
JLabel label = new JLabel();
label.setIcon(image);
this.getContentPane().add(label);
label.setBounds(10,10,100,100);
and there i see my image :-)
but 1 more thing, should i display all those blocks (images) on an applet, or should i use something else? (like what??)
a sort of frame?
because later on i have the field where all the blocks are in, and i have an area surrounding it, displaying all kinda information about the game, like how many lives remaining....
can i put 2 applets in eachother? like applet1 is the parent of applet2?
or should i use something else?
plz help me, cuz java is kinda new to me i see....
in delphi i just used 2 forms, form 1 with the blocks, form2 with the rest of info, and also being the parent of form1
thx again, soon i can help ya guys too, i hope..
(im learning java at school, but way too slow and to ez)
Ramon -
I have written a binary file with a specific header format in LABVIEW 8.6 and tried to Read the same Data File, Using LABVIEW 7.1.Here i Found some difficulty.Is there any way to Read the Data File(of LABVIEW 8.6), Using LABVIEW 7.1?
I can think of two possible stumbling blocks:
What are your 8.6 options for "byte order" and "prepend array or string size"?
Overall, many file IO functions have changed with LabVIEW 8.0, so there might not be an exact 1:1 code conversion. You might need to make some modifications. For example, in 7.1, you should use "write file", the "binary file VIs" are special purpose (I16 or SGL). What is your data type?
LabVIEW Champion . Do more with less code and in less time . -
Does LabView program behave differently under Traditional Chinese version from regular English version. The program reads in numbers and characters from input files.
Hope this helps,
Ankita -
Avoid Math.random() from looping the same number twice?
I'm trying to play a random gallary image by making it stops at different frame every few seconds, and the actions is completely random.
The problem is, since there are only 5 different images(5 frames) I'm displaying, there is a high probability that it stays at the same frame, how do I avoid that? Like avoid staying at the same page twice, if not run the function again....?
setInterval(createItems,throwItems);
var RandomImg:randomImg =new randomImg();
RandomImg.y=100;
RandomImg.x=180;
RandomImg.gotoAndStop(Math.floor(Math.random()*(1+5-1))+1);//generate random value between 1-5
addChild(RandomImg);
ThanksHow do I keep track of the random value, like what value should I put within the if to compare?
I try modify it a little, and wrap it within an if(), and use preValue to track down the previous frame, am I doing it right?
setInterval(createItems,throwItems);
var preValue:Number;
function createItems():void
var RandomImg:randomImg =new randomImg();
var randomFrame= Math.floor(Math.random()*(1+5-1))+1; //generate random value between 1-5
RandomImg.y=100;
RandomImg.x=180;
RandomImg.gotoAndStop(randomFrame);
if(preValue == randomFrame)
RandomImg.gotoAndStop(Math.floor(Math.random()*(1+5-1))+1);
addChild(RandomImg);
preValue = randomFrame;
}else
addChild(RandomImg);
preValue = randomFrame; -
I ordered the same app twice. The bill is pending. How do I delete my order as I dont want either of them?
All purchases are considered final, but you can try contacting iTunes support and see if they will refund or credit you : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption
-
When the first ipad came out i set it up and created an itunes account, since then she got an iphone and an ipad and everything was good. I had an android but wanted to try out the iphone. When i set it up ut jumpled all of our contacts, apps, and everythin. it was a mess.
Since, i purchased and ipad 2 and an iphone and to keep our stuff from combing i used a different computer and created an new apple ID for myself so our info wouldnt combine, I was wondering if i did the right thing or if i should have went about it a different way. I was going to see if there was a way when she purchased a song i could get it. I dont want to pay for the same song twice and only want to share songs. If i cant do this can i copy her library and paste it into my itunes??
Any help wouldl be greatly apprecieated we both have icloud set up but i cant figure out the best solution.Welcome to the world of digital media. Your can't really transfer it. I don't know what the rules are about transferring to your spouse but I do know that in some cases when you die, your heirs cannot inherit your digital media. This is why there is still an advantage to buying the CD since the usage rights belong to whomever holds the physical media.
A possible workaround is to burn the songs to a music CD with yout account (tracks only without song titles) and then having your wife upload it as a regular music CD onto her account. It's been a while since i've done this so I'm not sure if it would work now.
Please note that I'm not advocating copyright and/or TOS violations. I'm only suggesting ways to copy music for your own personal use which has traditonally been permitted. I only did this because I wanted to convert iTunes songs to mp3 files so I could burn them onto a data CD for use in my car. It would make sense that since married couples are a joint entity, this would be personal use.
Also, I'm not a lawyer so don't take this as legal advice.
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