Question

I’ve made an Applet Search Utility in which I provide a string as input and find that string in the specified file or folder.
I’ve done with this but I m not happy with its performance.
The process is taking too much time to respond.
I decided to do its profiling to see what is happening and I noticed that the method scanner.hasNextLine() is taking most of the time.
Though this is very important method for my program because I have to read all the lines and find that string, Is there any other way by which I can improve its performance and reduce the execution time

Here is the code where I am using this method ….

fw = new FileWriter("filePath", true);
        bw = new BufferedWriter(fw);

        for (File file : filenames) {
            if(file.isHidden())
                continue;

                if (!file.isDirectory()) {
                Scanner scanner = new Scanner(file);
                int cnt = 0;
                while (scanner.hasNextLine()) {
                    String line = scanner.nextLine();
                    if(!exactMatch)
                    {
                        if(!caseSensitive)
                        {
                            if (line.toLowerCase().contains(searchString.toLowerCase())) {
                                // System.out.println(line);
                                cnt += StringUtils.countMatches(line.toLowerCase(),
                                        searchString.toLowerCase());
                            }
                        }
                        else
                        {
                            if (line.contains(searchString)) {
                                // System.out.println(line);
                                cnt += StringUtils.countMatches(line,
                                        searchString);
                            }
                        }
                    }

And yes the method toLowerCase() is also taking more time then expected.

---

I have changed my code and now I am using BufferedReader in place of Scanner as Alex and Nrj suggested and I found a nice improvement in the performance of my application.
It is now processing in one third time of its earlier version.
Thanks to all that replied…..

Answer 1

Following your question I examined code of Scanner and I think that your are right. It is not optimized to work with large data. I’d recommend you to use simple BufferedReader that wraps InputStreamReader that wraps FileInputStream:

BufferedReader r = new BufferedReader(new InputStreamReader(new FileInputStream(fileName)))

then read line-by-line:

r.readLine()

If this is not enough for you try to read bulks of lines and then process them.

Concerning to toLowerCase() you can try to use regular expressions instead. The benefit is that you do not have to change the case of line every time. The disadvantage is that in simple cases regular expression works a bit slower than regular string comparison.