JDK version: 7-pro-b123

http://download.oracle.com/javase/7/docs/api/java/nio/file/Path.html#isSameFile(java.nio.file.Path) says:
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isSameFile

public abstract boolean isSameFile(Path other)
                            throws IOException
Tests if the file referenced by this object is the same file referenced by another object.
* If this Path and the given Path are equal then this method returns true without checking if the file exists. *
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This is true for default file system but not true for zip fils system. See the following code and output:

=====Begin of Code=====
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.Map;

import com.sun.nio.zipfs.ZipFileSystem;

import static java.lang.System.out;;

public class IsSameFile {

public static void main(String[] args) throws IOException {
Map<String, Object> env = new HashMap<String, Object>();
env.put("create", "true");
Path file = Paths.get("place_holder.zip");
file.deleteIfExists();
ZipFileSystem fs = (ZipFileSystem) FileSystems.newFileSystem(file, env,
null);

String nofile = "noSuchFile";

// test against default fs
out.println("test against default fs:");
out.println("exists? " + Paths.get(nofile).exists());
out.println("equals? " + Paths.get(nofile).equals(Paths.get(nofile)));
out.println(Paths.get(nofile).isSameFile(Paths.get(nofile)));

// test against Zip fs
out.println("test against zip fs:");
out.println("exists? " + fs.getPath(nofile).exists());
out.println("equals? " + fs.getPath(nofile).equals(fs.getPath(nofile)));
out.println(fs.getPath(nofile).isSameFile(fs.getPath(nofile)));

fs.close();
}
}

=====End of Code=====

=====Begin of Output=====
test against default fs:
exists? false
equals? true
true
test against zip fs:
exists? false
equals? true
Exception in thread "main" java.nio.file.NoSuchFileException: noSuchFile
at com.sun.nio.zipfs.ZipPath.checkAccess(ZipPath.java:825)
at com.sun.nio.zipfs.ZipPath.isSameFile(ZipPath.java:732)
at IsSameFile.main(IsSameFile.java:34)

=====End of Output=====