Best Way To Read / Write Files In Java?
Mar 31, 2014
I have seen different methods of creating and reading files (specifically text files) in Java. The PrintWriter method or the Formatter with a Scanner to read the file, using a BufferedWriter with a BufferedReader, etc. They will all read/write text files, but from what I understand they do so in different ways. When would it be more beneficial to use a buffered writer than, say, PrintWriter, which is much simpler code-wise? Is there a "best" way to handle i/o in general in Java?
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Jul 25, 2013
My background is mainframe and i'm new to java. We're moving from mainframe to the java world and I'm trying to achieve a task. I have a main folder and then bunch of sub folders and each sub folder has bunch of xml files, files size are varies some of them are 900kb. I need to read these xml files and send the output to the txt file (comma separated).
Some possible options or sample example... Please find below the sample xml file. I need to extract information's only where
FORM name="F00001".
[CODE]<PACKET>
<FORM name="F00001" sequence="0">
<FIELD sequence="1">02</FIELD>
<FIELD sequence="2">00000</FIELD>
<FIELD sequence="3">CAB100</FIELD>
<FIELD sequence="4">TEFAP001</FIELD>
<FIELD sequence="5">EMPTY FIELD</FIELD>
<FIELD sequence="6">009.999.989</FIELD>
[Code] .....
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Apr 21, 2014
I got a question in my last interview, its all about multithreading, interviewer asked me to write a program, to write the contents of three files(F1,F2,F3) in to a new File F4, using multithreading , first thread should read the first file and second thread should read second file, so the File F4 should contain F1's contents in first then F2's contents after that etc. I tried to give my best shot, but i couldn't get a way to ensure that the first thread is reading the first file and write to F4 then second thread reading the second file and writing once first file is written completely into F4 and so on ..how to do this?
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Apr 21, 2015
I have a requirement to read all the xml files from a parent folder and write in a spreadsheet(separate spreadsheet for each xml file)
I have written the below code in which xml and excel file name are hardcoded. The format of xml file is same.
package xmlexcel;
import org.apache.poi.hssf.usermodel.*;
import java.util.ArrayList;
import java.awt.List;
import java.io.*;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.xml.sax.SAXException;
[Code]...
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Sep 30, 2014
How can i use java for usb device? I want to read or write in a usb device in java. I've looked for in the web and i didn't find anything!
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Jun 19, 2014
How come that nobody has a normal name? ... like:
E40S,
EcAABtdtcC,
eveascavsa7242,
GrGGDahkcA,
HaHKNhibzB,
HbJFZqxsgR,
or almost nobody.
Second question, this is the exercise I have to make:
write a program that reads a sentence and write it on a file separating each word on a diffrent line of the file
Java Code:
package vacanze_estive_8;
import java.io.File;
import java.io.EOFException;
import java.io.PrintWriter;
import javax.swing.JOptionPane;
[Code] ....
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Apr 13, 2014
I am trying to write a program that read from a csv file called matches.csv.
A single football match can end with a win or a draw: in first case the winner team get 3 points and the loser none, in the second case of draw each of the two teams get 1 point.
For example, the first line of the file matches.txt is as follow:
In the file it contains the following data.
17/08/2013ArsenalAston Villa13
24/08/2013Aston VillaLiverpool01
This means that a match has been played on the 17/08/2013 where Arsenal scored 1 goal while Aston Villa 3 goals: thus Arsenal got 0 points while Aston Villa 3 points.
How can I structure my output to make it make it read
Position Team Played Points
1 Aston Villa 2 3
2 Liverpool 1 3
3 Arsenal 1 0
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Teams {
public static void main(String[] args) {
String fileName = "matches.csv";
File file = new File(fileName);
[code]....
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Apr 14, 2014
I am trying to write a program that read from a csv file called matches.csv.
A single football match can end with a win or a draw: in first case the winner team get 3 points and the loser none, in the second case of draw each of the two teams get 1 point.
For example, the first line of the file matches.txt is as follow:
In the file it contains the following data.
17/08/2013 Arsenal Aston Villa 1 3
24/08/2013 Aston Villa Liverpool 0 1
This means that a match has been played on the 17/08/2013 where Arsenal scored 1 goal while Aston Villa 3 goals: thus Arsenal got 0 points while Aston Villa 3 points.
How can I structure my output to make it make it read
Position Team Played Points
1 Aston Villa 2 3
2 Liverpool 1 3
3 Arsenal 1 0
Java Code:
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Teams
{
public static void main(String[] args)
{
String fileName = "matches.csv";
[Code] ....
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Feb 23, 2015
Write a java program to read the time intervals (HH:MM) and to compare system time if the system time between your time intervals print correct time and exit else try again to repeat the same thing. By using StringToknizer class.
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Nov 8, 2014
I am quite new to Java. I have downloaded a tictac example Java applet code and I run it on Eclipse with no problems. But when I try to test it outside Eclipse by doing the following:
I copy the .class file and two gif-images to another location and call the Java from html code:
<applet code="hello/HelloWorld.class" WIDTH="300" HEIGHT="300">
And I put the two gif-files to hello/images folder. I get and an error:
AccessControlException
access denied ("java.io.FilePermission")
"I:ImportantProgrammingWebProgramminghelloim ages
ot.gif" "read")
The path seems to be correct. I load the pictures from the Java code by:
notImage = getImage(getCodeBase(), "http://www.javaprogrammingforums.com/images/not.gif");
If I draw (drawLine) the X and O instead of using gif, then it works.... so its really the gif-loading which is the problem.
I have a Windows XP. I also tried to run it inside XAMPP server folder in my machine but the same problem. How could I be able to run it on my machine?
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Oct 10, 2014
Ex. If I type 5943, the program will say
mill = 5
hun = 9
ten = 4
uni = 3
get the picture I had to translate the decimal value names from a different language.
This is what I have tried...,
Java Code:
import java.util.Scanner;//Permite el uso de leer el teclado del usuario
public class DeterminarValorDecimal//Nombra el documento
{
public static void main(String [] args)//Podemos ver la clase
{
[Code].....
But what this does is I have to enter the single digits one by one. I want to be able to type the whole number. Is there a method that reads the length of the whole number and lets me classify each digit so I can do what I want to do?
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Apr 14, 2014
I have a question regarding the permissions set for generated heap dumps.
I have some Jetty servers running on Linux (Java 6 64 bit / Java 7 64 bit) with the following Java arguments:
-XX:+HeapDumpOnOutOfMemoryError
-XX:HeapDumpPath=/opt/apps/heapdump
When there is a out-of-memory exception a heap dump is automatically generated by the JVM. But it seems that the heap dump permisions are set to read-write for owner only (600).
When I create files then they have by default read-write for owner and group/all read access (644).
$ ls -l
total 795432
-rw------- 1 bamboop bamboo 811322265 Apr 14 09:18 java_pid337.hprof
-rw-r--r-- 1 bamboop bamboo 6 Apr 14 12:57 test
Here the umask set for the server running the Java processes
$ umask
0022
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Feb 16, 2015
I'm trying to write information into a file using PrintWriter. The program complies correctly but when it get's to the following part of the program, an error is given. "Exception in thread 'main' java.io.FileNotFoundException" What is wrong with it?
System.out.print("Enter the filename:");
filename = kb.nextLine();
PrintWriter outputFile = new PrintWriter(filename);
outputFile.println(balance);
outputFile.print(item1+" "+item1Price);
outputFile.println(" "+item1Quantity);
outputFile.print(item2+" "+item2Price);
outputFile.println(" "+item2Quantity);
outputFile.print(item3+" "+item3Price);
outputFile.println(" "+item3Quantity);
outputFile.close();
System.out.println("Data written to the file.");
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Feb 4, 2014
I am trying to do a read/write int property called currentQuestionIndex. This property is the index of the question currently selected, and the value of the property is 0 when a DrivingTest object is first created. I dont understand how to do this. I am not sure how to get the index of the current question. i was trying to use an iterator but i dont think i was doin it right. My question class that hold all my data
package cs320Labs.servlet;
public class Question {
String description;
String answerA;
String answerB;
String answerC;
int correctAnswer;
[Code] ....
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Jan 6, 2014
I have to write a diff which will compare two txt files, diff have to return changes and additional lines in console with indicating in what file and line.
Example:
File1:
This is war
on the front.
Flying is cool.
File2:
This is war
on the beach.
Something here.
Flying is cool.
Result of this should be:
Changed lines:
line2/line2 - on the front./beach.
file1 line2 on the front.
file2 line2 on the beach.
Additional lines:
file2 line3 Something here.
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Oct 28, 2014
I'm refitting a snippet of code I found on the net to write stuff into text files. After a bit of fiddling, here's what the code looks like in one of my classes:
public void addItem(String Item){
try{
Writer out = new OutputStreamWriter(fos, "UTF8");
out.append(Item);
out.flush();
// out.close();
}
catch (IOException e) {
System.out.println(e.toString());
}
}
The original snippet included the close() method. However, when I tried to do a test run writing multiple lines, I'd get an IOException about the stream being closed. I removed the close() method line, everything seems to work the way I want it, but I just wanna know if there's anything I'm missing out on by not having the close() method anywhere, especially when the IDE finds it important enough that it lit a warning about the stream not being closed somewhere as I was repurposing the original snippet.
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Dec 10, 2014
I'm trying to use graphics for my programs and here I'm trying to write a program that searches through files for text received from a JTextField. However, it does not seem to be working as my message is not displayed when text is found...
I used applet. Here are the functions:
JTextField jtf;
JFrame jf;
public void init()
[Code].....
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Jul 21, 2014
How do I get my program to read .txt files? My code doesn't work. I use eclipse.
I tried to use FileReader and BufferedReader objects, but the code doesn't work.
How do I get my program to read .txt files in java?
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Dec 30, 2014
I am fallowing programming tutorials on youtube.And this code is for reading zip files content.I did the same things like in the video.But Code dosent work
try {
ZipInputStream zis=
new ZipInputStream(new FileInputStream("C:UsersxxxDesktop ry.rar"));
ZipEntry zip;
while((zip=zis.getNextEntry())!=null){
jTextArea1.append(zip.getName());
zis.closeEntry();
}
zis.close();
} catch (FileNotFoundException ex) {
Logger.getLogger(Zip.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(Zip.class.getName()).log(Level.SEVERE, null, ex);
}
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Sep 16, 2014
how to read a netcdf file in java?
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Mar 17, 2014
I have a question for the read and write method in file.In my code for writing i m using PrintWriter and for reading Scanner.So i m saving data to file and when is need it i m reading from the file.but i also have to delete specific data from it.Is there a way to delete a specific line from the file?When i google my problem i found that is better to save your data to temporary file and then to the final.
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Jun 4, 2014
I want to read and write json to/from a file. I read the following document:
JsonReader (Java(TM) EE 7 Specification APIs)
I try to define a JsonReader object in Eclipse:
JsonReader jr
But there appears to be no import for it. Where I am supposed to get the Json library?
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Oct 17, 2014
I'm rather new to programming and I'm trying to make a gui program that will allow the user to create text files. They will be prompted to enter what they'd like to save their file as and then they will be allowed to input text to that file . They will also be allowed to open their files to modify or view its contents. So to start things off, I'm making a prototype if you will.. I've been able to save to a file the problem occurs when I try to read/display it.
Main Class:
public class MainActivity {
public static void main(String[] args) {
// Access to other classes
WriteFile writer = new WriteFile();
ReadFile reader = new ReadFile();
[Code] ....
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Apr 15, 2015
To read or write to a USB device must use an external library?
Such as this? usb4java - About
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Apr 14, 2015
I need to read folder structure from the excle file and need to read all the files which are available inside folder structure.folder structure like below
c:Migrate
C:MigrateMigrateFiles
...
...
..etc.
I am ble to read files which is avalibale in all the folders with single thread,i want to read those files with multiple threads,each thread shoud reads the files from different folder. here how to read.
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Apr 30, 2015
I've written a program to read files in a directory but I'd like for it to only read the text files of that directory.
import java.io.*;
public class Data {
public static void main(String[] args) throws IOException {
String target_dir = "C:files";
File dir = new File(target_dir);
File[] files = dir.listFiles();
[Code] .....
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