Re: Improving performance of code

Hi,
I'm reading a file and doing some operations on it..It is a huge file
going in GB's.....
The code is working correctly but is very slow....How do i optimise
it...
My code snipnet is:
class Risk
{
   public void compare(String infile) throws IOException
        {
                cnt=0;
                for(i=0;i<qid.size();i++)
                {
                        no=0;
                        fr=new FileReader(infile);
                        br=new BufferedReader(fr);
                        while((str=br.readLine())!=null)
                        {
                                no++;
                                if((str.startsWith("$"))||(str.startsWith("-CONT-")))
                                        continue;
                                else
                                {
                                        s2=str.substring(0,10);
                                        if(s2.equals(qid.elementAt(i)))
                                        {
                                                cnt++;
                                                start=no;
                                                end=no+29;
                                                quadarray(infile,start,end);
                                        }

                                        if((cnt==sc) && (i<qid.size()))
                                        {
                                                System.out.println("qid="+qid.elementAt(i));
                                                cnt=0;
                                                writesubcase1();
                                        }
                                }
                        }
                        fr.close();

                }

                               for(i=0;i<tid.size();i++)
                {
                        no=0;
                        fr=new FileReader(infile);
                        br=new BufferedReader(fr);
                        while((str=br.readLine())!=null)
                        {
                                no++;
                                if((str.startsWith("$"))||(str.startsWith("-CONT-")))
                                        continue;
                                else
                                {
                                        s2=str.substring(0,10);
                                        if(s2.equals(tid.elementAt(i)))
                                        {
                                                cnt++;
                                                start=no;
                                                end=no+29;
                                                triaarray(infile,start,end);
                                        }
                                        if((cnt==sc) && (i<tid.size()))
                                        {
                                                System.out.println("tid="+tid.elementAt(i));
                                                cnt=0;
                                                writesubcase2();
                                        }
                                }
                        }
                        fr.close();
                }
        }

        public void quadarray(String ifile,int start,int end) throws
IOException
        {
                try
                {
                        fr1=new FileReader(ifile);
                        br1=new BufferedReader(fr1);
                        line=0;
                        k=0;
                        x=0;
                        while((str1=br1.readLine())!=null)
                        {
                                line++;
                                if((line>=start) && (line<end))
                                {
                                        if(j==0)
                                                quad[j][k]=str1;
                                        if((k==3) ||(k==17)||(k= ))
                                        {
                                                val1=Double.parseDouble(str1.substring(18,36));
                                                if(val1>qmax[x])
                                                {
                                                        qmax[x]=val1;
                                                        x++;
                                                }
                                        }
                                        if((k==5) ||(k==8)||(k==22)||(k==25))
                                        {
                                                val2=Double.parseDouble(str1.substring(54,72));
                                                if(val2>qmax[x])
                                                {
                                                        qmax[x]=val2;
                                                        x++;
                                                }
                                        }
                                        if((k==11)||(k==14)||(k==28))
                                        {
                                                val3=Double.parseDouble(str1.substring(36,54));
                                                if(val3>qmax[x])
                                                {
                                                        qmax[x]=val3;
                                                        x++;
                                                }
                                        }
                                        k++;
                                }
                        }
                }
                catch (Exception e)
                { }
        }

        public void writesubcase1() throws IOException
        {
                x=0;
                try
                {
                        fw=new FileWriter("Result.txt",true);
                        for(y=0;y<30;y++)
                        {
                                if((y==0)||(y==1)||(y==2)||(y==4)||(y==6)||(y==7)||(y==9)||
(y==10)||(y==12)||(y==13)||(y==15) || (y==16)||(y==18)||(y==19)||
                                        (y==21)||(y==23)||(y==24) || (y==26)||(y==27))
                                {
                                        fw.write(quad[0][y]+"\n");
                                        continue;
                                }
                                else
                                {
                                        if((y==3)||(y==17)||(y= ))
                                        {
                                                s=quad[0][y];
                                                fw.write(s.substring(0,28)+qmax[x]+s.substring(37)+"\n");
                                                x++;
                                                continue;
                                        }
                                        if((y==5)||(y==8)||(y==22)||(y==25))
                                        {
                                                s=quad[0][y];
                                                fw.write(s.substring(0,64)+qmax[x]+"\n");
                                                x++;
                                                continue;
                                        }
                                        if((y==11)||(y==14))
                                        {
                                                s=quad[0][y];
                                                fw.write(s.substring(0,46)+qmax[x]+s.substring(55)+"\n");
                                                x++;
                                                continue;
                                        }
                                        if(y==28)
                                        {
                                                s=quad[0][y];
                                                fw.write(s.substring(0,46)+qmax[x]+"\n");
                                                x++;
                                                break;
                                        }
                                }
                        }
                        fw.close();
                }
                catch(Exception e)
                {}
        }

        public void triaarray(String ifile,int start,int end) throws
IOException
        {
                try
                {
                        fr1=new FileReader(ifile);
                        br1=new BufferedReader(fr1);
                        line=0;
                        while((str1=br1.readLine())!=null)
                        {
                                line++;
                                if((line>=start) && (line<end))
                                {
                                        if(j==0)
                                                tria[j][k]=str1;
                                        if(k==2)
                                        {
                                                val1=Double.parseDouble(str1.substring(37,54));
                                                if(val1>tmax[0])
                                                        tmax[0]=val1;
                                        }
                                        if(k==5)
                                        {
                                                val2=Double.parseDouble(str1.substring(19,36));
                                                if(val2>tmax[1])
                                                        tmax[1]=val2;
                                        }
                                        k++;
                                }
                        }
                }
                catch(Exception e)
                {}
        }

        public void writesubcase2()
        {
                try
                {
                        fw=new FileWriter("Result.txt",true);
                        for(y=0;y<7;y++)
                        {
                                if((y==0)||(y==1)||(y==3)||(y==4))
                                {
                                        fw.write(tria[0][y]+"\n");
                                        continue;
                                }
                                if(y==2)
                                {
                                        s=tria[0][y];
                                        fw.write(s.substring(0,47)+tmax[0]+s.substring(55)+"\n");
                                        continue;
                                }
                                if(y==5)
                                {
                                        s=tria[0][y];
                                        fw.write(s.substring(0,29)+tmax[1]+"\n");
                                        break;
                                }
                        }
                        fw.close();
                }
                catch(Exception e)
                {}
        }

        public static void main(String args[])
        {
          Risk r=new Risk();
          ipfile=args[0];

                try
                {
                    r.compare(ipfile);
                }
                catch (Exception e)
                { }
        }

}

The code takes a lot of time in functions Quadarray and Triaaray.
As u can see the de is very simple in these functions but still it
takes lot of time...

How do i improve it??