Copy file in Java and replace existing target

Question

I'm trying to copy a file with java.nio.file.Files like this:

Files.copy(cfgFilePath, strTarget, StandardCopyOption.REPLACE_EXISTING);

The problem is that Eclipse says "The method copy(Path, Path, CopyOption...) in the type Files is not applicable for the arguments (File, String, StandardCopyOption)"

I'm using Eclipse and Java 7 on Win7 x64. My project is set up to use Java 1.6 compatibility.

Is there a solution to this or do I have to create something like this as a workaround:

File temp = new File(target);

if(temp.exists())
  temp.delete();

Thanks.

Answer 1

As a complement to @assylias' answer:

If you use Java 7, drop File entirely. What you want is Path instead.

And to get a Path object matching a path on your filesystem, you do:

Paths.get("path/to/file"); // argument may also be absolute

Get used to it real fast. Note that if you still use APIs which require File, Path has a .toFile() method.

Note that if you are in the unfortunate case where you use an API which returns File objects, you can always do:

theFileObject.toPath()

But in code of yours, use Path. Systematically. Without a second thought.

EDIT Copying a file to another using 1.6 using NIO can be done as such; note that the Closer class is inspited by Guava:

public final class Closer
    implements Closeable
{
    private final List<Closeable> closeables = new ArrayList<Closeable>();

    // @Nullable is a JSR 305 annotation
    public <T extends Closeable> T add(@Nullable final T closeable)
    {
        closeables.add(closeable);
        return closeable;
    }

    public void closeQuietly()
    {
        try {
            close();
        } catch (IOException ignored) {
        }
    }

    @Override
    public void close()
        throws IOException
    {
        IOException toThrow = null;
        final List<Closeable> l = new ArrayList<Closeable>(closeables);
        Collections.reverse(l);

        for (final Closeable closeable: l) {
            if (closeable == null)
                continue;
            try {
                closeable.close();
            } catch (IOException e) {
                if (toThrow == null)
                    toThrow = e;
            }
        }

        if (toThrow != null)
            throw toThrow;
    }
}

// Copy one file to another using NIO
public static void doCopy(final File source, final File destination)
    throws IOException
{
    final Closer closer = new Closer();
    final RandomAccessFile src, dst;
    final FileChannel in, out;

    try {
        src = closer.add(new RandomAccessFile(source.getCanonicalFile(), "r");
        dst = closer.add(new RandomAccessFile(destination.getCanonicalFile(), "rw");
        in = closer.add(src.getChannel());
        out = closer.add(dst.getChannel());
        in.transferTo(0L, in.size(), out);
        out.force(false);
    } finally {
        closer.close();
    }
}