Accessing Files and Directories - Beginning Java

Java Reference

In-Depth Information

the example, the new directory will be created in the current directory because the path is relative. You see

this exception thrown if you execute the code fragment twice. It can throw a NoSuchFileException if any

of the parents for the required directory do not exist. The createDirectory() method also throws an ex-

ception of type java.io.IOException if an I/O error occurs. These exceptions are checked exceptions so

you should call the method from within a try block and provide for catching at least the IOException ex-

ception; this catches the other exception because it is a subclass of IOException .

If the Path object refers to an absolute path, the parent path for the new directory must already exist if

the creation is to succeed with the createDirectory() method. When you have the possibility that some

elements in the path for a directory that you want to create may not exist, you can call the static createDir-

ectories() method that is defined in the Files class with the Path object as the argument. This creates all

the required directories. Here's an example:

Path path = Paths.get("D:/Garbage/dir/dir1/dir2");

try {

Files.createDirectories(path);

} catch(IOException e) {

e.printStackTrace(System.err);

}

If any of the subdirectories of the final directory dir2 do not exist, they are created. When you are creat-

ing a new directory that you specify by an absolute path, using the createDirectories() method obviates

the need to verify that the parent exists. As well as the IOException , this method can throw an exception

of type FileAlreadyExistsException if a file already exists with the same path. If the directory already

exists, this exception is not thrown. If the createDirectories() method fails for some reason, some of the

parent directories may be created before the failure occurs.

Let's try creating some directories in an example.

TRY IT OUT: Creating Directories

Here's an example that uses both methods for creating directories:

import java.nio.file.*;

import java.io.IOException;

public class CreatingDirectories {

public static void main(String[] args) {

Path relPath = Paths.get("junkDir");

createSingleDirectory(relPath);

// Create directory in current

createSingleDirectory(relPath);

// then try it again...

Path absPath = Paths.get("D:/Garbage/dir1/dir2/dir3");

createSingleDirectory(absPath);

// Try creating as single