A usefull way to read a long file

Question

Hi,
What's the best and usefullest way to read a large file?
I do use a LineNumberReader but i think it reads a little slow...
To open the same file in an text editor reacts in less a millisecond while my LineNumberReader nees more time to read the entire file...
Any suggestions?
Olek

Answer 1

re,
how can i determine how a file contains "real" text or only sensles characters?
The file i readed seems to be a binary file in your meaning.
here is the method i use
// Threader.FileReadThreader is a instance of SwingWorker
public static String readPlainTextFile(File f, Threader.FileReadThreader fileReader) throws IOException {
        final StringBuilder strBuild = new StringBuilder();
        final DataInputStream dis = new DataInputStream(new BufferedInputStream(new FileInputStream(f)));
        final int readByte = BUFFER;
        final int fileLength = (int) f.length();
        float step = fileLength / readByte;
        byte[] buffer = new byte[fileLength];
        int off = 0;
        if (fileReader != null) {
            float percent = 0F;
            while (off < fileLength - readByte) {
                dis.readFully(buffer, off, readByte);
                String tempSequence = new String(Arrays.copyOfRange(buffer, off, off + readByte - 1));
                strBuild.append(tempSequence);
                off += readByte;
                percent += step;
                fileReader.doPublish(new Object[]{Math.round(percent), tempSequence});
            // read the remaining bytes
            int last = fileLength - off;
            dis.readFully(buffer, off, last - 1);
            String tempSequence = new String(Arrays.copyOfRange(buffer, off, off + last - 1));
            strBuild.append(tempSequence);
            percent += step;
            fileReader.doPublish(new Object[]{Math.round(percent), tempSequence});
            return strBuild.toString();
        } else {
            dis.readFully(buffer);
            return new String(buffer);
    }As you can see i modified your code.
Hm i got the error why the JTextArea do only display
one large line of characters...
i forgot to set line wrap ...
but now the app freezes reading the large binary file ...
with a smaller file all works ok.
Any ideas?
regards.
Olek