How to find sub-directories in a directory/folder?

问题

I'm looking for a way to get all the names of directories in a given directory, but not files.

For example, let's say I have a folder called Parent, and inside that I have 3 folders: Child1 Child2 and Child3.

I want to get the names of the folders, but don't care about the contents, or the names of subfolders inside Child1, Child2, etc.

Is there a simple way to do this?

回答1:

You can use String[] directories = file.list() to list all file names, then use loop to check each sub-files and use file.isDirectory() function to get subdirectories.

For example:

File file = new File("C:\\Windows");
String[] names = file.list();

for(String name : names)
{
    if (new File("C:\\Windows\\" + name).isDirectory())
    {
        System.out.println(name);
    }
}

回答2:

If you are on java 7, you might wanna try using the support provided in

package java.nio.file

If your directory has many entries, it will be able to start listing them without reading them all into memory first. read more in the javadoc: http://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#newDirectoryStream(java.nio.file.Path,%20java.lang.String)

Here is also that example adapted to your needs:

public static void main(String[] args) {
    DirectoryStream.Filter<Path> filter = new DirectoryStream.Filter<Path>() {
        @Override
        public boolean accept(Path file) throws IOException {
            return (Files.isDirectory(file));
        }
    };

    Path dir = FileSystems.getDefault().getPath("c:/");
    try (DirectoryStream<Path> stream = Files.newDirectoryStream(dir, filter)) {
        for (Path path : stream) {
            // Iterate over the paths in the directory and print filenames
            System.out.println(path.getFileName());
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

回答3:

public static void displayDirectoryContents(File dir) {
    try {
        File[] files = dir.listFiles();
        for (File file : files) {
            if (file.isDirectory()) {
                System.out.println("Directory Name==>:" + file.getCanonicalPath());
                displayDirectoryContents(file);
            } else {
                System.out.println("file Not Acess===>" + file.getCanonicalPath());
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}

====inside class/Method provide File=URL ======

    File currentDir = new File("/home/akshya/NetBeansProjects/");
    displayDirectoryContents(currentDir);
}

来源：https://stackoverflow.com/questions/13533479/how-to-find-sub-directories-in-a-directory-folder

标签

java