Java Reference
In-Depth Information
The following snippet shows how to append data to an existing file:
File file - out = new File ( " old.dat " );
FileOutputStream out = new FileOutputStream (file - out, true);
The second parameter in the constructor indicates that the file should be opened
for appending. RandomAccessFile can also be used for appending. It is dis-
cussed in the Web Course Chapter 9: Supplements section.
9.6.1 Text output to a file
We can use the FileWriter stream class to write character data to a file. The
following PrintWriterFileApp example gets the name for an output file
either from a parameter on the command line or from a default. The program
follows closely to PrintWriterApp in Section 9.4.1 except that instead of
starting with the PrintStream object referenced by System.out ,wecreate
a FileWriter for a File object and then wrap this with a BufferedWriter
and a PrintWriter . These two wrappers give us the efficiency of stream buffer-
ing and a handy set of print methods.
import java.io.*;
/**
*Demonstrate wrapping streams to send text and primitive
*type values to a file.
**/
public class PrintWriterFileApp
{
public static void main (String[] args) {
File file = null;
// Get the file from the argument line.
if (args.length > 0) file = new File (args[0]);
if (file == null) {
System.out.println ( " Default: textOutput.txt " );
file = new File ( " textOutput.txt " );
}
// Create a FileWriter stream to a file and then wrap
// a PrintWriter object around the FileWriter to print
// primitive values as text to the file.
try {
// Create a FileWriter stream to the file
FileWriter file - writer = new FileWriter (file);
 
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