Question

I have to fetch 500K rows from the database and write that data into the file , Means perform the I/O operation . I have done for two steps .

1. Write each row one by one into the file .
2. Make the chunk of those rows .Append those rows in StringBuffer and then print it . This one will be better but is there any way that File I/O can make the buffer on it’s own without using StringBuffer . As this String Buffer is taking more time (Internally it use Arrays.copyOf)

Please suggest me on this
Please find the code attached with this

public void fetchDataWithChunkSpace(Connection con)throws Exception
        {
            String query ="select * from lis.testxml  ";
            long startTime=new Date().getMinutes();
            PreparedStatement stmt = con.prepareStatement(query);
            ResultSet rs = stmt.executeQuery();
            PrintWriter pw = new PrintWriter(new File("c:\\test_chunkSpace.xml"));
            pw.write("<?xml version='1.0' encoding='UTF-8'?>");
            StringBuffer sb = new StringBuffer();
            String t=null; 
            long count =0;
            while(rs.next())
            {   count++;
                t = rs.getString("xmltest");
                sb = sb.append(t);
                if(count%100==0)
                {
                 pw.write(sb.toString());
                 sb = new StringBuffer();
                 System.out.println(count);
                }
            }
            pw.write("\n");
            pw.write("</EndTag>");
            pw.close();
            stmt.close();
            con.close();
            long endTime=new Date().getMinutes();
            System.out.println("chunkSpace  ---> " + (endTime-startTime));
        }

Answer 1

Look at BufferedOutputStream or BufferedWriter.

Also consider that StringBuffer is thread-safe class with synchronyzed methods unlike StringBuilder.

Update.
Try this code:

Writer pw = new BufferedWriter(new PrintWriter(new File("c:\\test_chunkSpace.xml")));
pw.write("<?xml version='1.0' encoding='UTF-8'?>");
String t;
while (rs.next()) {
    t = rs.getString("xmltest");
    pw.write(t);
}