OOP Passing parameter back

[Roberto Gonsales]

Hello everybody, I need some help. I'm writing program which takes bunch of text files with different charset encoding and converts these files to another one charset. My program is almost done, but one key thing. How do I pass 'charset' parameter of Notify method in CharsetDetector class back to Converter class?

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package masscharsetconverter;

import java.io.*;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author Boris
 */
public class Converter {

    String path = "d:\\Projects\\charsetconverter\\html's\\";

    public Converter() {
        File folder = new File(path);
        File[] contents = folder.listFiles();

        for (File file : contents) {
            
            try {
                CharsetDetector det = new CharsetDetector();
                det.detectCharset(file);
                
                
                String fileCharset = "";
                
                Reader in = new InputStreamReader(new FileInputStream(file), fileCharset);
                Writer out = new OutputStreamWriter(new FileOutputStream(file), "ASCII");
                int c;
                
                while ((c = in.read()) != -1) {
                    out.write(c);
                }
                
                in.close();
                out.close();
            } catch (IOException ex) {
                Logger.getLogger(Converter.class.getName()).log(Level.SEVERE, null, ex);
            } 

        }
    }
}

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package masscharsetconverter;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.mozilla.intl.chardet.HtmlCharsetDetector;
import org.mozilla.intl.chardet.nsDetector;
import org.mozilla.intl.chardet.nsICharsetDetectionObserver;
import org.mozilla.intl.chardet.nsPSMDetector;

/**
 *
 * @author Boris
 */
public class CharsetDetector implements nsICharsetDetectionObserver {

    private nsDetector det;

    public CharsetDetector() {
        // Initalize the nsDetector() ;
        int lang = nsPSMDetector.ALL;
        det = new nsDetector(lang);


        // Set an observer...
        // The Notify() will be called when a matching charset is found.
        det.Init(this);
    }

    public void detectCharset(File file) {
        byte[] buf = new byte[1024];
        int len;
        boolean done = false;
        boolean isAscii = true;
        
        try {
            BufferedInputStream bStream = new BufferedInputStream(new FileInputStream(file));
            while ((len = bStream.read(buf, 0, buf.length)) != -1) {

                // Check if the stream is only ascii.
                if (isAscii) {
                    isAscii = det.isAscii(buf, len);
                }

                // DoIt if non-ascii and not done yet.
                if (!isAscii && !done) {
                    done = det.DoIt(buf, len, false);
                }
            }
        } catch (IOException ex) {
            Logger.getLogger(CharsetDetector.class.getName()).log(Level.SEVERE, null, ex);
        }
        det.DataEnd();

        if (isAscii) {
            System.out.println("CHARSET = ASCII");
            
            //Charset is ASCII, pass this back to Converter class
            
        }
    }

    @Override
    public void Notify(String charset) {
        HtmlCharsetDetector.found = true;
        System.out.println("CHARSET = " + charset);
        
        //Charset is in 'charset' parameter, pass it back to Converter class
        
    }
}

[Greg Charles]

I'm not clear on when or why your notify() method is called, but I think the most logical way to get the results of detectCharset() into your converter would be to return it from detectCharset().

A couple of extra suggestions:

1. Wrap your reader and writer in BufferedReader and BufferedWriter and you'll see a dramatic increase in performance.
2. Learn the capitalization conventions for Java. Classes and Interfaces should start with a capital. Methods and variables start with lowercase. Following conventions like these make your code much more readable.

[Roberto Gonsales]

Greg, thank you for reply. I changed code in accordance with your recommendations to use BufferedReader and BufferedWriter.
Interface nsICharsetDetectionObserver is part of jChardet library. nsDetector fires the Notify() method between nsDetector.DoIt() and nsDetector.DataEnd() calls. I changed CharsetDetector class to get result only in Notify() method. So how do I get the result back to Converter class?

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package masscharsetconverter;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.mozilla.intl.chardet.HtmlCharsetDetector;
import org.mozilla.intl.chardet.nsDetector;
import org.mozilla.intl.chardet.nsICharsetDetectionObserver;
import org.mozilla.intl.chardet.nsPSMDetector;

/**
 *
 * @author Boris
 */
public class CharsetDetector implements nsICharsetDetectionObserver {

    private nsDetector det;

    public CharsetDetector() {
        // Initalize the nsDetector() ;
        int lang = nsPSMDetector.ALL;
        det = new nsDetector(lang);


        // Set an observer...
        // The Notify() will be called when a matching charset is found.
        det.Init(this);
    }

    public void detectCharset(File file) {
        byte[] buf = new byte[1024];
        int len;
        boolean done = false;
        boolean isAscii = true;
        
        try {
            BufferedInputStream bStream = new BufferedInputStream(new FileInputStream(file));
            while ((len = bStream.read(buf, 0, buf.length)) != -1) {

                // Check if the stream is only ascii.
                if (isAscii) {
                    isAscii = det.isAscii(buf, len);
                    Notify("ASCII");
                }

                // DoIt if non-ascii and not done yet. Result will be in the Notify() method
                if (!isAscii && !done) {
                    done = det.DoIt(buf, len, false);
                }
            }
        } catch (IOException ex) {
            Logger.getLogger(CharsetDetector.class.getName()).log(Level.SEVERE, null, ex);
        }
        det.DataEnd();
    }

    @Override
    public void Notify(String charset) {
        HtmlCharsetDetector.found = true;
        System.out.println("CHARSET = " + charset);
        
        //Charset is in 'charset' parameter, pass it back to Converter class
        
    }
}