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??