Reading and Writing Files
You’ve already learned how to chain an
OutputStreamWriter
to a
FileOutputStream
and an
InputStreamReader
to a
FileInputStream
. Although this isn’t hard,
Java provides two simple utility classes that take care of the
details, java.io.FileWriter
and
java.io.FileReader
.
FileWriter
The FileWriter
class is a subclass of
OutputStreamWriter
that writes text files using
the platform’s default character encoding and buffer size. If
you need to change these values, construct an
OutputStreamWriter
on a
FileOutputStream
instead.
public class FileWriter extends OutputStreamWriter
This class has four constructors:
public FileWriter(String fileName) throws IOException public FileWriter(String fileName, boolean append) throws IOException public FileWriter(File file) throws IOException public FileWriter(FileDescriptor fd)
The first constructor opens a file and positions the file pointer at the beginning of the file. Any text in the file is overwritten. For example:
FileWriter fw = new FileWriter("36.html");
The second constructor allows you to specify that new text is appended to the existing contents of the file rather than overwriting them by setting the second argument to true. For example:
FileWriter fw = new FileWriter("36.html", true);
The third and fourth constructors use a File
object and a FileDescriptor
, respectively, instead
of a filename to identify the file to be written to. Any pre-existing
contents in a file so opened are overwritten.
No methods other than the constructors ...
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