file « nio « Java I/O Q&A

1. What are some tips for processing large files in Java

I need to perform a simple grep and other manipulations on large files in Java. I am not that familiar with the Java NIO utilities, but I am assuming that ...

2. How to determine if a file will be logically moved or physically moved

The facts: When a file is moved, there's two possibilities:

  1. The source and destination file are on the same partition and only the file system index is updated
  2. The source and destination are on ...

3. Java.NIO InvalidIndexException - how to read and write with random access to large files

I've created a java.nio.MappedByteBuffer around a (a file which is only 54 KB in size). The resulting MappedByteBuffer has a "capacity" and "limit" of around 12 KB, so when I ...

4. Where is java.nio.file

I'm new to java so I am not familiar with the framework yet. I am reading java documentation that tells me there should be a java.nio.file namespace. But when I attempt ...

5. Problem with import java.nio.file

Why this line doesn't work?

import static java.nio.file.AccessMode.*;
Eclipse says:
The import java.nio.file cannot be resolved
Here is the whole program so far:
import static java.nio.file.AccessMode.*;

public class CheckFileAccessibility {
 public static void main(String[] args) {

I ...

6. Java, IO - fastest way to remove file

My problem is that I have an app which is writing a lot of relatively (100-500kb) small CSV files (tens and hundreds of thousands ). Content of those files then get ...

7. Does it make sense to use `java.nio.file.spi`to implement access to a remote file system?

Basically I write an application which copies/moves files from the local file system to a remote file system over some FTP-like protocol. Would it be a good approach to encapsulate the protocol-specific ...

8. Non-Blocking File IO in Java

I want to write to a named pipe (already created) without blocking on the reader. My reader is another application that may go down. If the reader does go down, I ...

9. Problem with NIO whily trying to copy large file

I have the code to copy a file to another location.

public static void copyFile(String sourceDest, String newDest) throws IOException {

    File sourceFile = new File(sourceDest);

10. Working with files and file systems: Before NIO, with NIO and with NIO2 in the future

Before Java 1.4 it was common practice to work with files by moving bytes around between different InputStreams/OutputStreams. Since Java 1.4, where NIO got added, it is suggested to use ...

11. Java MemoryMapping big files

The Java limitation of MappedByteBuffer to 2GIG make it tricky to use for mapping big files. The usual recommended approach is to use an array of MappedByteBuffer and index it through:

long ...

12. Problem importing java.nio.file.* package

I am trying to create a watchdog file and so I have been trying to use java.nio.file package. I have even installed jdk7 but still I get the error "package java.nio.file ...

13. Java 7: What charset shall I use when calling Files.newBufferedReader?

In previous versions of Java, I would read a file by creating a buffered reader like this:

BufferedReader in = new BufferedReader(new FileReader("file.txt"));
In Java 7, I would like to use

14. Java NIO causes file descriptor leak

We have a http server which is implemented based on Java NIO. It is running on Ubuntu 10.04.2 LTS with java version "1.6.0_20" Java(TM) SE Runtime Environment (build 1.6.0_20-b02) Java HotSpot(TM) Server VM (build ...

15. Best way to write String to file using java nio

I need to write(append) huge string to flat file using java nio. The encoding is ISO-8859-1. Currently we are writing as shown below. Is there any better way to do the ...

16. Silent error while copying files

I have the following method of copying files:

public static void nioCopy(File source, File destination) {
    FileInputStream fis = null;
    FileOutputStream fos = null;

17. JDK 7 java.nio.file isSymbolicLink() behavior

I am trying to use the FileWalkTree() method in JDK 7 (java.nio.file) . To implement my own FileVisitor I have created a CustomFileVIsitor class by extending SimpleFileVisitor. In this CustomFileVIsitor class ...

18. Is File.length platform and filesystem independant

Image I catch a stream of the net and count how many bytes went through my hands, I write this stream to a file. Is the number of counted bytes guranteed ...

19. Java7 / enum constructor / Files.createTempDirectory(String prefix, FileAttribute... attrs)

I'd like to create a Path instance for an enum constructor:

/** Temporary paths. */
public enum PATHS {

    /** First temporary directory. */
    PATH1(Files.createTempDirectory(new StringBuilder("tnk").append(File.separator).append("path1")

20. Java error (package java.nio.file does not exist import java.nio.file.*;)

I am new and learning Java. I tried running the following application in Netbeans 7.

import java.nio.file.*;
import java.nio.file.StrandardOpenOption.*;

public class FileOut

    public static void main(String[] args)

21. Reading a file using NIO

Hello there, I need help reading a file and storing it as a byte array. I have a bitmap file that I want to read in, and store as a byte[]. Is this possible with NIO. I looked at FileChannels but I can't seem to figure out how to do it. Any help would be greatly appreciated. Thanks. Vinu.

22. NIO not suitable for small files ?

23. nio and file transfers

nio and file transfers (I/O and Streams forum at JavaRanch) A friendly place for programming greenhorns! Register / Login Java Forums Java I/O and Streams nio and file transfers Post by: Jose Botella, Ranch Hand on Apr 27, 2004 09:33:00 I am learning nio and I want to share my testing code. FileTX transmits files to several remote hosts ...

24. NIO and updating a file region

I have (what I thought would be) a simple problem. I have a data file that needs to be updated. For example, I have a 100 byte array with the up-to-date information and I want to replace or update bytes 450 - 550 in the file with the new 100 bytes. When I set the postion of the file to byte ...

25. reading big file using java nio

Hi i using java nio for reading java file whoes size is upto 3 gb,currently i am geeting an The parameter is incorrect i send my code import*; import java.nio.*; import java.nio.channels.*; public class MappedChannelRead { public static void main(String args[]) { FileInputStream fIn; FileChannel fChan; long fSize; byte buf[]=new byte[98]; MappedByteBuffer mBuf; int pos,lim; try { fIn=new FileInputStream("f:\\DataFile");//file ...

26. NIO with large files

background: i have to do some processing of large text files -- 1 GB and larger, and i'll be processing as many as 12 in a row. "larger": i have one file that is 3.5 GB. something like, going through a directory of these files and processing each one. i'm trying to work out how i can do this efficiently, and ...

27. package java.nio.file does not exist

30. java.nio.file

31. JDK 7 : Java NIO.2 : File Change Notification

33. java.nio.file.Files setOwnership problems

Hi, I am building a simple script to sift through directories/files and set the ownership of files so they can be accessed and deleted. I am attempting to set the ownership of a file that is owned by another user when file permissions are restricted to only that user. I am wondering, how can I overcome this because using setOwner() method ...

34. NIO WatchService and file modifications

Hi everyone, I am just testing a little bit the new I/O API and facing a fancy issue : I created a WatchService that prints informations when a file is modified ( StandardWatchEventKinds.ENTRY_MODIFY ). When I modify the file using NotePad (I work on Windows), all is OK, I have one trace of the modification. But if I modify the file ...