Writing Files - Beginning Java - page 442

OutputStream object in a BufferedOutputStream object, you are able to use the write() meth-
od for the buffered stream object to write binary data to the file efficiently.
• The newBufferedWriter() method opens or creates a file specified by a Path object for writing
in text mode. The BufferedWriter object that the method returns provides an efficient way to
write textual data to a file.
• The newByteChannel() method opens a file specified by a Path object that can be accessed at
random for writing and/or reading. The data written or read can be binary or textual data.
The Files class also defines two static write() methods that can write either a byte[] array to a file
or an Iterable set of lines as characters. I'll concentrate on the three possibilities in the above list because
these are the most useful. Let's start by exploring how you can write a file using an OutputStream object in
more detail.

WRITING A FILE VIA AN OUTPUT STREAM
The newOutputStream() method in the Files class expects the first argument to be a Path object encap-
sulating the path to the file to be written. You can supply one or more optional arguments to specify open
options for the file from the java.nio.file.StandardOpenOption enumeration. These determine how the
file is opened and where the data goes when you write to it. You can use the options presented in Table 10-1
in this context.

TABLE 10-1 : Output Options Defined by the StandardOpenOption Enumeration
OPTION DESCRIPTION
CREATE Create a new file if the file does not already exist.
CREATE_NEW Create a new file, but fail the operation if the file already exists.
DELETE_ON_CLOSE Delete the file when the stream is closed. This is primarily for use with work files that are only
required during execution of your program.
APPEND Write new data to the end of the file.
TRUNCATE_EXISTING Truncate the existing file length to 0 so new data is written from the beginning, overwriting any
previous data.

Open the file for write access. WRITE

The enumeration also defines the following constants, as presented in Table 10-2 .

TABLE 10-2 : Output Options Defined by the StandardOpenOption Enumeration
OPTION DESCRIPTION
READ Opens the file for read access.
SPARSE Provides a hint to improve efficiency for file systems that support sparse files.
SYNC Requires that all file updates are written synchronously to the storage device. This causes the return from the

write method to wait until all data and metadata have been written to the storage device. This is to ensure the
integrity of files in the event of a system crash.

This has the same effect as SYNC but only in relation to file data, not metadata. DSYNC

You use the READ option in the next chapter.
If you don't specify any arguments to the newOutputStream() method after the first, the default options
in effect are WRITE , CREATE , and TRUNCATE_EXISTING . This means that by default a new file is created if