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!");
    }
    }
}

Answer 1

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!)

Answer 2

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 .

Answer 3

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();
    }
 }

}