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Groups > comp.lang.java.programmer > #8547

Re: slow as molasses

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Looks like you pretty much figured it out.  Kudos to you.

Here is the new code (which is maybe about 100x faster):

	float[] getVertices2(String filename) {

		try {
			AssetManager am = this.getResources().getAssets();
			InputStream is = am.open(filename);
			BufferedInputStream bis = new BufferedInputStream(is);

			StreamTokenizer st = new StreamTokenizer(bis);
			st.nextToken();
			int numfloats = (int) st.nval;
			float[] f = new float[(int) numfloats];

			int token = 0;
			int ctr = 0;

			while ((token = st.nextToken()) == StreamTokenizer.TT_NUMBER)
				f[ctr++] = (float) st.nval;


			return f;

		} catch (IOException e) {
			e.printStackTrace();
			return null;
		}

	}


Thanks so much.


On Oct 4, 12:30 pm, "John B. Matthews" <nos...@nospam.invalid> wrote:
> In article
> <e160619b-d172-4986-8e05-880d27473...@k15g2000yqd.googlegroups.com>,
>
>  bob <b...@coolgroups.com> wrote:
> > So, I wrote some code, but it is slow as molasses.  Any easy ways to
> > speed this up?
> [...]
> >                    Scanner s = new Scanner(is);
>
> [...]
>
> After measuring, buffering and considering double, helpfully
> suggested in adjacent answers, StreamTokenizer [1] may prove
> measurably faster than Scanner [2]. One caveat: StreamTokenizer
> can't parse scientific notation. Workaround's are possible [3,4],
> although I haven't tested any.
>
> Focusing on just the parsing, the example below produces the
> following results:
>
> Token: 5165000
> Scan:  681903000
> Token: 427000
> Scan:  185379000
> Token: 878000
> Scan:  63467000
> Token: 398000
> Scan:  63480000
> Token: 570000
> Scan:  62084000
>
> import java.io.IOException;
> import java.io.StreamTokenizer;
> import java.io.StringReader;
> import java.util.Random;
> import java.util.Scanner;
>
> public class ScannerTest {
>
>     private static final Random r = new Random();
>     private static final int N = 10000;
>
>     public static void main(String[] args) {
>         StringBuilder sb = new StringBuilder(N);
>         for (int i = 0; i < N; i++) {
>             sb.append(r.nextGaussian());
>             sb.append('\n');
>         }
>         String s = sb.toString();
>         for (int i = 0; i < 5; i++) {
>             long start = System.nanoTime();
>             tokenize(s);
>             System.out.println("Token: " + (System.nanoTime() - start));
>             start = System.nanoTime();
>             scan(s);
>             System.out.println("Scan:  " + (System.nanoTime() - start));
>         }
>     }
>
>     private static void tokenize(String s) {
>         StreamTokenizer st = new StreamTokenizer(new StringReader(s));
>         int token = 0;
>         try {
>             while ((token = st.nextToken())
>                     == StreamTokenizer.TT_NUMBER) {
>                 double d = st.nval;
>             }
>         } catch (IOException e) {
>             e.printStackTrace(System.err);
>         }
>     }
>
>     private static void scan(String s) {
>         Scanner scanner = new Scanner(s);
>         while (scanner.hasNextDouble()) {
>             double d = scanner.nextDouble();
>         }
>         scanner.close();
>     }
>
> }
>
> [1]<http://download.oracle.com/javase/7/docs/api/java/io/StreamTokenizer....>
> [2]<http://stackoverflow.com/questions/2082174>
> [3]<http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4079180>
> [4]<http://www.resplendent.com/StlFileParser.java>
>
> --
> John B. Matthews
> trashgod at gmail dot com
> <http://sites.google.com/site/drjohnbmatthews>

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slow as molasses bob <bob@coolgroups.com> - 2011-10-04 02:16 -0700
  Re: slow as molasses Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-10-04 11:28 +0000
  Re: slow as molasses Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-10-04 07:47 -0700
  Re: slow as molasses Patricia Shanahan <pats@acm.org> - 2011-10-04 08:42 -0700
  Re: slow as molasses "John B. Matthews" <nospam@nospam.invalid> - 2011-10-04 13:30 -0400
    Re: slow as molasses bob <bob@coolgroups.com> - 2011-10-04 14:19 -0700

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