Chapter 11
The java.io Package

FileWriter

Name

FileWriter

Synopsis

Class Name:

java.io.FileWriter

Superclass:

java.io.OutputStreamWriter

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

New as of JDK 1.1

The FileWriter class represents a character stream that writes data to a file. It is a subclass of OutputStreamWriter that uses a default buffer size (8192 bytes) to write bytes to a file and the default character encoding scheme to convert characters to bytes. If you need to specify the character encoding or the buffer size, wrap an OutputStreamWriter around a FileOutputStream.

The file can be specified using a FileDescriptor, a File object, or a String that represents a pathname. All of the constructors can throw a SecurityException if the application does not have permission to write to the specified file.

FileWriter provides a low-level interface for writing character data to a file. You should think about wrapping a FileWriter with a BufferedWriter to increase writing efficiency.

If you need to write binary data to a file, you should use a FileOutputStream wrapped by a DataOutputStream or a PrintStream instead.

Class Summary

public class java.io.FileWriter extends java.io.OutputStreamWriter {
  // Constructors
  public FileWriter(String fileName);
  public FileWriter(String fileName, boolean append);
  public FileWriter(File file);
  public FileWriter(FileDescriptor fd);
}

Constructors

FileWriter

public FileWriter(String fileName) throws IOException

Parameters

fileName: The pathname of the file to use as output.

Throws

FileNotFoundException

If the named file cannot be found.

SecurityException

If the application does not have permission to write to the named file.

Description

This constructor creates a FileWriter that sends its output to the file named by the specified String.

 public FileWriter(String fileName, boolean append) throws IOException

Parameters

fileName

The pathname of the file to use as output.

append

Specifies whether or not data is appended to the output stream.

Throws

FileNotFoundException

If the named file cannot be found.

SecurityException

If the application does not have permission to write to the named file.

Description

This constructor creates a FileWriter that sends its output to the named file. If append is true, the stream is positioned at the end of the file, and data is appended to the end of the file. Otherwise, if append is false, the stream is positioned at the beginning of the file, and any previous data is overwritten.

public FileWriter(File file) throws IOException

Parameters

file: The File to use as output.

Throws

FileNotFoundException

If the named file cannot be found.

SecurityException

If the application does not have permission to write to the named file.

Description

This constructor creates a FileWriter that sends its output to the file represented by the specified File object.

public FileWriter(FileDescriptor fdObj)

Parameters

fdObj: The FileDescriptor of the file to use as output.

Throws

SecurityException

If the application does not have permission to write to the specified file.

NullPointerException

If FileDescriptor is null.

Description

This constructor creates a FileWriter that sends its output to the file identified by the given FileDescriptor.

Inherited Methods

Method	Inherited From	Method	Inherited From
`clone()`	`Object`	`close()`	`OutputStreamWriter`
`equals(Object)`	`Object`	`finalize()`	`Object`
`flush()`	`OutputStreamWriter`	`getClass()`	`Object`
`getEncoding()`	`OutputStreamWriter`	`hashCode()`	`Object`
`notify()`	`Object`	`notifyAll()`	`Object`
`toString()`	`Object`	`wait()`	`Object`
`wait(long)`	`Object`	`wait(long, int)`	`Object`
`write(int)`	`OutputStreamWriter`	`write(char[])`	`Writer`
`write(char[], int, int)`	`OutputStreamWriter`	`write(String)`	`Writer`
`write(String, int, int)`	`OutputStreamWriter`