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java zip filesystem reading zip entries

SO, from what I've gathered, one is supposed to be able to create a filesystem from a zip from java 7 and beyond. I'm trying this, the ultimate goal is to use the File object and access these files, just as if I accessed an unzipped file.
import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.nio.file.*;
import java.util.*;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
public class MainZipTest {
public static void main(String[] args) throws IOException, URISyntaxException {
Map<String, String> env = new HashMap<>();
env.put("read", "true");
File file = new File("C:/pathtoazip/data.zip");
URI uri = file.toURI();
String path = "jar:" + uri;
FileSystem fs = FileSystems.newFileSystem(URI.create(path), env);
for (Path p : fs.getRootDirectories()) {
System.out.println("root" + p);
//says "/"
System.out.println(new File(p.toString()).exists());
for (File f : new File(p.toString()).listFiles())
System.out.println(f.getAbsolutePath());
//lists the contents of my c drive!
}
System.out.println(new File("somefile.txt").exists());
System.out.println(fs.getPath("somefile.txt").toFile().exists());
System.out.println(new File("/somefile.txt").exists());
System.out.println(fs.getPath("/somefile.txt").toFile().exists());
}
}
it all prints "false". What am I doing wrong here? Or am I wrong in my assumption that I can access these files through the File object? If so, how does one access them?

Path was introduced as generalization of File (disk file). A Path can be inside a zip file, an URL, and more.
You can use Files with Path for similar File functionality.
for (Path p : fs.getRootDirectories()) {
System.out.println("root: " + p);
System.out.println(Files.exists(p));
Files.list(p).forEach(f -> System.out.println(f.toAbsolutePath()));
}
Note that a Path, like from a zip will maintain its actual file system view (fs, the zip).
So avoid File.

Can a Jar File be updated programmatically without rewriting the whole file?

It is possible to update individual files in a JAR file using the jar command as follows:
jar uf TicTacToe.jar images/new.gif
Is there a way to do this programmatically?
I have to rewrite the entire jar file if I use JarOutputStream, so I was wondering if there was a similar "random access" way to do this. Given that it can be done using the jar tool, I had expected there to be a similar way to do it programmatically.

It is possible to update just parts of the JAR file using Zip File System Provider available in Java 7:
import java.net.URI;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.util.HashMap;
import java.util.Map;
public class ZipFSPUser {
public static void main(String [] args) throws Throwable {
Map<String, String> env = new HashMap<>();
env.put("create", "true");
// locate file system by using the syntax
// defined in java.net.JarURLConnection
URI uri = URI.create("jar:file:/codeSamples/zipfs/zipfstest.zip");
try (FileSystem zipfs = FileSystems.newFileSystem(uri, env)) {
Path externalTxtFile = Paths.get("/codeSamples/zipfs/SomeTextFile.txt");
Path pathInZipfile = zipfs.getPath("/SomeTextFile.txt");
// copy a file into the zip file
Files.copy( externalTxtFile,pathInZipfile,
StandardCopyOption.REPLACE_EXISTING );
}
}
}

Yes, if you use this opensource library you can modify it in this way as well.
https://truevfs.java.net
public static void main(String args[]) throws IOException{
File entry = new TFile("c:/tru6413/server/lib/nxps.jar/dir/second.txt");
Writer writer = new TFileWriter(entry);
try {
writer.write(" this is writing into a file inside an archive");
} finally {
writer.close();
}
}

Moving large files in java

I have to move files from one directory to other directory.
Am using property file. So the source and destination path is stored in property file.
Am haivng property reader class also.
In my source directory am having lots of files. One file should move to other directory if its complete the operation.
File size is more than 500MB.
import java.io.File;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;
import static java.nio.file.StandardCopyOption.*;
public class Main1
{
public static String primarydir="";
public static String secondarydir="";
public static void main(String[] argv)
throws Exception
{
primarydir=PropertyReader.getProperty("primarydir");
System.out.println(primarydir);
secondarydir=PropertyReader.getProperty("secondarydir");
File dir = new File(primarydir);
secondarydir=PropertyReader.getProperty("secondarydir");
String[] children = dir.list();
if (children == null)
{
System.out.println("does not exist or is not a directory");
}
else
{
for (int i = 0; i < children.length; i++)
{
String filename = children[i];
System.out.println(filename);
try
{
File oldFile = new File(primarydir,children[i]);
System.out.println( "Before Moving"+oldFile.getName());
if (oldFile.renameTo(new File(secondarydir+oldFile.getName())))
{
System.out.println("The file was moved successfully to the new folder");
}
else
{
System.out.println("The File was not moved.");
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
System.out.println("ok");
}
}
}
My code is not moving the file into the correct path.
This is my property file
primarydir=C:/Desktop/A
secondarydir=D:/B
enter code here
Files should be in B drive. How to do? Any one can help me..!!

Change this:
oldFile.renameTo(new File(secondarydir+oldFile.getName()))
To this:
oldFile.renameTo(new File(secondarydir, oldFile.getName()))
It's best not to use string concatenation to join path segments, as the proper way to do it may be platform-dependent.
Edit: If you can use JDK 1.7 APIs, you can use Files.move() instead of File.renameTo()

Code - a java method:
/**
* copy by transfer, use this for cross partition copy,
* #param sFile source file,
* #param tFile target file,
* #throws IOException
*/
public static void copyByTransfer(File sFile, File tFile) throws IOException {
FileInputStream fInput = new FileInputStream(sFile);
FileOutputStream fOutput = new FileOutputStream(tFile);
FileChannel fReadChannel = fInput.getChannel();
FileChannel fWriteChannel = fOutput.getChannel();
fReadChannel.transferTo(0, fReadChannel.size(), fWriteChannel);
fReadChannel.close();
fWriteChannel.close();
fInput.close();
fOutput.close();
}
The method use nio, it make use os underling operation to improve performance.
Here is the import code:
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
If you are in eclipse, just use ctrl + shift + o.

How to copy-paste, and cut-paste file or folder in java?

I made a desktop app in java with netbeans platform. In my app I want to give separate copy-paste and cut-paste option of file or folder.
So how can I do that? I tried Files.copy(new File("D:\\Pndat").toPath(),new File("D:\\212").toPath(), REPLACE_EXISTING);. But I don't get the exact output.
If there any other option then suggest me.

In case of "cut-paste" you can use renameTo() like this:
File source = new File("////////Source path");
File destination = new File("//////////destination path");
if (!destination.exists()) {
source.renameTo(destination);
}
In case of "copy-paste" you need to read in Input and Output stream.

Use FileUtils from apache io and do FileUtils.copyDirectory(sourceDir, destDir);
You can also do the following file operations
writing to a file
reading from a file
make a directory including parent directories
copying files and directories
deleting files and directories
converting to and from a URL
listing files and directories by filter and extension
comparing file content
file last changed date
Download link for apache i/o jar.

I think this question relates to using the system clipboard for copying a file specified in a Java app and using the OS "Paste" function to copy the file to a folder. Here is a short instructional example that will show you how to add a single file to the OS clipboard for later doing an OS "Paste" function. Tweak as necessary and add error/exception checking as needed.
As a secondary, this code also places the file name on the clipboard so you can paste the file name into document editors.
package com.example.charles.clipboard;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.ClipboardOwner;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
public class JavaToSystemClipboard {
public static void main(final String[] args) throws Exception {
final File fileOut = new File("someFileThatExists");
putFileToSystemClipboard(fileOut);
}
public static void putFileToSystemClipboard(final File fileOut) throws Exception {
final Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
final ClipboardOwner clipboardOwner = null;
final Transferable transferable = new Transferable() {
public boolean isDataFlavorSupported(final DataFlavor flavor) {
return false;
}
public DataFlavor[] getTransferDataFlavors() {
return new DataFlavor[] { DataFlavor.javaFileListFlavor, DataFlavor.stringFlavor };
}
public Object getTransferData(final DataFlavor flavor) {
if (flavor.equals(DataFlavor.javaFileListFlavor)) {
final List<String> list = new ArrayList<>();
list.add(fileOut.getAbsolutePath());
return list;
}
if (flavor.equals(DataFlavor.stringFlavor)) {
return fileOut.getAbsolutePath();
}
return null;
}
};
clipboard.setContents(transferable, clipboardOwner);
}
}

You can write things by yourself using FileOutputStream and FileInputStream or you can used Apache Camel.

Java.nio.files - Copying files

Can anyone tell me what I've done wrong with the following code. I receive no errors - it just goes straight to the catch.
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
public class Main {
public static void main(String[] args) {
Path source = Paths.get("C:\\Users\\Public\\Pictures\\SamplePictures");
Path nwdir = Paths.get("D:\\NetbeansProjects\\CopyingFiles\\copiedImages");
try{
Files.copy(source, nwdir);
}catch (IOException e){
System.out.println("Unsucessful. What a surprise!");
}
}
}

If you take a look at the Javadocs of Files.copy, you'll notice this line (emphasis added):
If the file is a directory then it creates an empty directory in the target location (entries in the directory are not copied). This method can be used with the walkFileTree method to copy a directory and all entries in the directory, or an entire file-tree where required.
So it looks like you need to use that walkFileTree method.
(And as the commenters said, print out exceptions and they'll often tell you what's wrong!)

Came across here looking for a NIO Java7 approach to recursively copy a directory to another location. This can be done with Files.walkFileTree as Jon7 mentioned in the other anwer. This code I got for a simple directory copy:
final Path srcDir, final Path dstDir;
Files.walkFileTree(srcDir, new SimpleFileVisitor<Path>() {
public FileVisitResult visitFile( Path file, BasicFileAttributes attrs ) throws IOException {
return copy(file);
}
public FileVisitResult preVisitDirectory( Path dir, BasicFileAttributes attrs ) throws IOException {
return copy(dir);
}
private FileVisitResult copy( Path fileOrDir ) throws IOException {
Files.copy( fileOrDir, dstDir.resolve( srcDir.relativize( fileOrDir ) ) );
return FileVisitResult.CONTINUE;
}
});
For a more detailed example which also handles file attributes and overwriting of existing files, see http://docs.oracle.com/javase/tutorial/essential/io/examples/Copy.java .

This is how I have managed to copy a file from one location to another:
import java.io.IOException;
import static java.nio.file.StandardCopyOption.*;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
public class App {
public static void main(String[] args)
{
Path source = Paths.get("E:/myFile.pdf");
Path nwdir = Paths.get("F:");
try
{
Files.copy(source, nwdir.resolve(source.getFileName()), REPLACE_EXISTING);
System.out.println("File Copied");
}
catch(IOException e)
{
e.printStackTrace();
}
}
}