Accessing Files and Directories - Beginning Java - page 421

ception must be last, because the other two exception types are derived from IOException . The output
shows that when this method is called for the relative path, relPath , the first time around the directory is
created and the second time FileAlreadyExistsException is thrown, as you would expect. Calling the
method for the absolute path, absPath , causes NoSuchFileException to be thrown because the parent
path does not exist. Since the actions are the same for both, you catch either of them as type IOExcep-
tion in a single catch block.
The createMultipleDirectories() method calls the static createDirectories() method in the
Files class. The createDirectories() method creates all the directories required for the path and
therefore the directory specified by absPath is created when createMultipleDirectories() is called.
The second time the method is called, no exception is thrown. If the directory that is specified by
the Path object that is passed to createDirectories() already exists, the method does nothing.
FileAlreadyExistsException is thrown only when there is a file or symbolic link with the same name
as the requested directory already in existence.
Creating Files
To create a new empty file you can call the static createFile() method in the Files class with the Path
object that specifies the file path as the argument. If the file already exists, the FileAlreadyExistsExcep-
tion exception is thrown by the method. The method also throws an exception of type IOException if an
I/O error occurs. Note that the parent directory for the new file must exist before you create the file. The
createFile() method throws an exception of type java.nio.file.NoSuchFileException if the parent
directory does not exist. Here's an example:
Path path = Paths.get("D:/Garbage/dir/dir1/dir2/junk.txt");
try {
Files.createFile(path);
} catch(NoSuchFileException e) {
System.err.println("File not created.\n" + e);
} catch(FileAlreadyExistsException e) {
System.err.println("File not created.\n" + e);
} catch(IOException e) {
System.err.println(e);
}
The fragment above creates the file with the name junk.txt in the dir2 directory. If the parent directory
for the file does not exist, the exception of type NoSuchFileException is thrown and caught in this case.
Of course, you could always ensure that the parent directory exists, like this:
Path path = Paths.get("D:/Garbage/dir/dir1/dir2/junk.txt");
try {
Files.createDirectories(path.getParent()); // Create parent
Files.createFile(path);
} catch(FileAlreadyExistsException e) {
System.err.println("File not created.\n" + e);
} catch(IOException e) {
System.err.println(e);
}