Program throws NullPointerException when i try to search in drives?

Question

I wrote a program to find file or directory.
Its working properly when i am trying to Search file with in Directory
example
java FileSea

Answer 1

Another alternative is to using the FileVisitor interface introduced in JDK7 to perform the search. The link at http://docs.oracle.com/javase/tutorial/essential/io/walk.html provides details on how to use the FileVisitor interface.

The following code block is a re implementation of the search that should be able to list files at a windows drive level in addition to normal directories. Note that the implementation uses Files.walkTree method that is provided as part of the NIO 2 File IO Operations.

public class FileSearch {
    static String fd;
    static boolean flg = true;

    static class FileSearchVisitor extends SimpleFileVisitor {

        private final Path pathToSearch;

        boolean found;

        FileSearchVisitor(Path pathToSearch) {
            found = false;
            this.pathToSearch = pathToSearch;
        }

        public boolean isFound() {
            return found;
        }

        @Override
        public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
            super.preVisitDirectory(dir, attrs);
            if (pathToSearch.getFileName().equals(dir.getFileName())) {
                System.out.println("Found " + pathToSearch);
                found = true;
            }
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
            super.visitFile(file, attrs);
            if (pathToSearch.getFileName().equals(file.getFileName())) {
                System.out.println("Found " + pathToSearch);
                found = true;
            }
            return FileVisitResult.CONTINUE;
        }

        @Override
        public FileVisitResult visitFileFailed(Path file, IOException exc) {
            System.err.println("Visit failed for file at path : " + file);
            exc.printStackTrace();
            return FileVisitResult.CONTINUE;
        }

    }

    public static void main(String arr[]) throws Exception {
        fd = arr[0];
        String path = arr[1];

        final Path searchFile = Paths.get(fd);
        Path filePath = Paths.get(path);
        FileSearchVisitor visitor = new FileSearchVisitor(searchFile);
        Files.walkFileTree(filePath, visitor);
        if (!visitor.isFound()) {
            System.out.print("File not found.");
        }
    }
}