Q: Why does my Java code dealing with files run perfectly on my Unix system,
but it breaks when I move it to the Macintosh?
A: The file path specification in Java is different than Unix. Keep your
Java code platform independent by avoiding the use of any of the following common
Unix-isms:
- Do not assume a directory "
/tmp" exists and is writable. As
an alternative, when using MRJ, you can use the MRJToolkit to locate the Temporary
Items Folder. See the sample class below:
import java.io.File;
import java.io.FileNotFoundException;
import com.apple.mrj.MRJFileUtils;
public class MRJTempFolder
{
/**
* Returns the Temporary Items Folder on the Mac OS.
* @return a File object representing the Temporary Items Folder,
* or null, if it could not be found.
*/
public static File getTempFolder()
{
File tempFolder = null;
try
{
tempFolder = MRJFileUtils.findFolder(MRJFileUtils.kTemporaryFolderType);
}
catch (FileNotFoundException exc) { }
return tempFolder;
}
}
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- Do not assume "
/dev/null" exists as a way to write to the bit
bucket. Instead, subclass java.io.OutputStream and implement write(int)
as an empty method, then pass an instance of the subclass to System.setOut
via the java.io.PrintStream constructor. See the example class below:
import java.io.*;
/**
* A repository for unwanted bytes.
* Basically a replacement for <code>/dev/null</code>
*/
public class BitBucketOutputStream extends OutputStream
{
/**
* Sets System.out to use the BitBucketOutputStream as the output
* stream. In effect, redirecting standard out to oblivion.
* @see restoreSystemOut
*/
public static void nullSystemOut()
{
System.setOut(new PrintStream(new BitBucketOutputStream(), true));
}
/**
* Recreates a System.out similar to the default System.out, and restores
* the default behavior.
* @see #nullSystemOut
*/
public static void restoreSystemOut()
{
FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
System.setOut(new PrintStream(new BufferedOutputStream(fdOut, 128), true));
}
/**
* Sets System.err to use the BitBucketOutputStream as the output
* stream. In effect redirecting standard error to oblivion.
* @see restoreSystemErr
*/
public static void nullSystemErr()
{
System.setErr(new PrintStream(new BitBucketOutputStream(), true));
}
/**
* Recreates a System.err similar to the default System.err, and restores
* the default behavior.
* @see #nullSystemErr
*/
public static void restoreSystemErr()
{
FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
System.setErr(new PrintStream(new BufferedOutputStream(fdErr, 128), true));
}
/**
* Does nothing with the specified byte.
*
* @param b the <code>byte</code> to ignore.
* @exception IOException if an I/O error occurs.
*/
public void write(int b) throws IOException
{ }
}
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