Martin Baker wrote:
> My question is: what is the most efficient way to read in large arrays of
> numbers? (such as a very big IndexedFaceSet)
> I get the impression that the most 'architecturally sound' way to do
> formatted I/O is to use the java.text package.
Not really. I only ever use this when writing data out, not reading.
> So I tend to read the file one line at a time, use StringTokenizer to split
> it up, then convert to a double floating point number using something like:
>
> value = (new Double(s)).doubleValue();
Yuck. You are better off using StreamTokeniser (in java.io) and just
splitting it based on the separator char - assuming linefeeds are not
important. Here is one method of doing it:
InputStream is = // however you open it.
double[] data = new double[some_size];
StreamTokenizer strtok = new StreamTokenizer(is);
strtok.eolIsSignificant(false);
strtok.parseNumbers();
strtok.whitespaceChars(','); // set up comma delimited if needed
strtok.commentChar('#'); // set up # as a comment char if needed
int i = 0;
int type;
while((type = strtok.nextToken()) != StringTokenizer.TT_EOF)
{
switch(type)
{
case StringTokenizer.TT_NUMBER:
data[i++] = strtok.nval;
break;
case StringTokenizer.TT_WORD:
// do something or toss it away
break;
case .....
}
}
Alternatively, there is also a static parseDouble() method for the
String. This saves on allocation.
try
{
double dbl = Double.parseDouble(s);
}
catch(NumberFormatException nfe)
{
}
--
Justin Couch Author, Java Hacker
Snr Software Engineer [EMAIL PROTECTED]
ADI Ltd, Systems Group http://www.vlc.com.au/~justin/
Java3D FAQ: http://tintoy.ncsa.uiuc.edu/~srp/java3d/faq.html
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