Java - Calcolare lunghezza di un file wave

import java.io.*;
import javax.sound.sampled.*;

public class SimpleAudioRecorder
extends Thread {
    private TargetDataLine		m_line;
    private AudioFileFormat.Type	m_targetType;
    private AudioInputStream	m_audioInputStream;
    private File			m_outputFile;

    public SimpleAudioRecorder(TargetDataLine line,
    AudioFileFormat.Type targetType,    File file) 
    {
        m_line = line;
        m_audioInputStream = new AudioInputStream(line);
        m_targetType = targetType;
        m_outputFile = file;
    }
    public void start() {
        m_line.start();
        super.start();
    }
    public void stopRecording() {
        m_line.stop();
        m_line.close();
    }
    public void run() {
        try {
            AudioSystem.write(
            m_audioInputStream,
            m_targetType,
            m_outputFile);
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        if (args.length != 1 || args[0].equals("-h")) {
            System.out.println("SimpleAudioRecorder: usage:");
            System.out.println("\tjava SimpleAudioRecorder -h");
            System.out.println("\tjava SimpleAudioRecorder <audiofile>");
            System.exit(0);
        }

        String	strFilename = args[0];
        File	outputFile = new File(strFilename);

        AudioFormat  audioFormat = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED,    44100.0F, 16, 2, 4, 44100.0F, false);

        DataLine.Info   info = new DataLine.Info(TargetDataLine.class, audioFormat);
        TargetDataLine  targetDataLine = null;
        try {
            targetDataLine = (TargetDataLine) AudioSystem.getLine(info);
            targetDataLine.open(audioFormat);
        }
        catch (LineUnavailableException e) {
            System.out.println("unable to get a recording line");
            e.printStackTrace();
            System.exit(1);
        }

        AudioFileFormat.Type	targetType = AudioFileFormat.Type.WAVE;
        SimpleAudioRecorder	recorder = new SimpleAudioRecorder(
        targetDataLine,
        targetType,
        outputFile);

        System.out.println("Press ENTER to start the recording.");
        try {
            System.in.read();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        recorder.start();
        System.out.println("Recording...");
        System.out.println("Press ENTER to stop the recording.");
        try {
            System.in.read();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        recorder.stopRecording();
        System.out.println("Recording stopped.");
    }
}