Java.nio.files - Copying files

Question

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 print out e.getMessage() in the catch, then it might tell you. — Richante, Apr 12 '12 at 15:40
If you print your stacktrace, you might have a better clue as to what is going on. Add e.printStackTrace(System.out) into your catch block. — Matthew Farwell, Apr 12 '12 at 15:40
Have you tried, for example, `e.printStackTrace()` ? You'll get a better description of the problem. — Ernest Friedman-Hill, Apr 12 '12 at 15:41

score 7 · Accepted Answer · edited Jun 02 '14 at 12:34

7

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!)

edited Jun 02 '14 at 12:34

joews

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answered Apr 12 '12 at 15:52

Jon7

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java.nio.file.NoSuchFileException: C:\Users\Public\Pictures\SamplePictures at sun.nio.fs.WindowsException.translateToIOException(WindowsException.java:79) at sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:97) at sun.nio.fs.WindowsException.rethrowAsIOException(WindowsException.java:102) at sun.nio.fs.WindowsFileCopy.copy(WindowsFileCopy.java:99) at sun.nio.fs.WindowsFileSystemProvider.copy(WindowsFileSystemProvider.java:277) at java.nio.file.Files.copy(Files.java:1219) at Main.main(Main.java:14) – user1311422 Apr 12 '12 at 16:46
1

That's nice, but, as I said, your code will not work because you're trying to do a recursive copy with a function that cannot do recursive copies. Take a look at the API link that I provided. – Jon7 Apr 12 '12 at 16:53
By recursive copy, do you mean the directory and the files and directories within samplepictures. If so - I have changed the path to link directly to a single .jpg file with the same error. Apologies if im missing your point. – user1311422 Apr 12 '12 at 17:12
No problem. What did you end up doing to fix it? – Jon7 Apr 12 '12 at 17:17
The directory "Sample pictures" had a space in it. I thought java would complain because of the spaces, so I renamed it "SamplePictures". However, this didn't update the path. Another problem that occurred was my nwdir. I thought the path would be where I wanted the file. This is correct, but it also needs the file name. – user1311422 Apr 12 '12 at 17:40

score 4 · Answer 2 · answered Feb 06 '14 at 13:33

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 .

Beware that `srcDir.relativize( fileOrDir )` will throw a `ProviderMismatchException` if you use this to copy across different file systems, for example, from a ZipFile to default. — Dilum Ranatunga, Jun 30 '14 at 08:15

score 2 · Answer 3 · answered Aug 27 '14 at 16:49

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();
    }
 }

}

Java.nio.files - Copying files

3 Answers3