Ghi tiếp File

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.swing.JOptionPane;

public class GhiTiepFile {
    public static void main(String[] args) {
        String duonglink = "/home/thieumao/Desktop/GhiTiepFileDo.txt";
        String themvao = "Noi dung can ghi";
        BufferedReader br = null;
        BufferedWriter bw = null;
        try {
            br = new BufferedReader(new InputStreamReader(new FileInputStream(
                    duonglink)));
            String line = "";
            String newLine = "";
            while ((line = br.readLine()) != null) {
                newLine = newLine + line + "\n";
            }
            bw = new BufferedWriter(new FileWriter(duonglink));
            newLine = newLine + themvao;
            bw.write(newLine);
            bw.flush();
        } catch (FileNotFoundException ex) {
            JOptionPane.showMessageDialog(null, "Duong dan bi sai");
            System.exit(0);
        } catch (IOException ex) {
            Logger.getLogger(GhiTiepFile.class.getName()).log(Level.SEVERE,
                    null, ex);
        } finally {
            try {
                bw.close();
                br.close();
            } catch (IOException ex) {
                Logger.getLogger(GhiTiepFile.class.getName()).log(Level.SEVERE,
                        null, ex);
            }
        }

    }
}