[Webinar] Streamline your web hosting managementRegister Today

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 702
  • Last Modified:

Efficiency in using File object and RandomAccessFile Object

I have 2 piece of code that reads in data from a text file.One of them uses a File Object and the other uses RandomFileAccess as follows:



(1)File Object code:

filename = "c:\\data.dat";

File loaddata = new File(filename)

try
{
    if ( !userdefinefile.exists())
    {
     return;
    }
    else
    {
     BufferedReader br = new BufferedReader(new FileReader(userdefinefile));
                   
        while ( br.readLine() != null)
     {          
            //code to process each line until end of file
        }
         

}catch (Exception ex) {}




(2)RandomAccessFile object code:

filename = "c:\\data.dat"

try
{
    RandomAccessFile loaddata = new RandomAccessFile(filename, "rw");

    while( loaddata.readLine() != null)
    {
        //code to process each line read.
    }
}
catch( Exception ex ){}




The problem is that the code using the RandomAccessFile object seem to be slower that the code using File Object
.Can anybody tell why this is so? And how can I improve the efficiency of using RandomAccessFile Object readLin() method?
0
jerntat
Asked:
jerntat
  • 2
  • 2
1 Solution
 
tonusCommented:
Is it because of RandomAccessFile traffics in bytes rather than characters.
0
 
tonusCommented:
Again you can read the entire file at one stratch using RAF


Here is the code

  RandomAccessFile loaddata = new RandomAccessFile(filename, "rw");

  Byte[] byteArray = new Byte[(int)loaddata.length()];

loaddata.readFully(byteArray);
0
 
jerntatAuthor Commented:
but you are still reading in the same amount of data whether in byte or chracters,shouldnt both method at least uses the same amount of time

I only wanted to read a small part of the file at a time because i dont want to use too much memory.
0
 
dnoelppCommented:
Just a comment:

No, a character is two bytes (since it's Unicode).

And as for efficiency, Java IO is not very efficient. I really don't know very much why you found a difference, so I can't help you here. I can give you some hints for exploring the difference.

Optimizing Java IO is very helpful because with some effort you can gain savings of several hundred percents in speed. Using a BufferedReader can accelerate reading by a factor of 10 and more. Using a big buffer (several kB till a MB) can make a difference, too, but at the expense of memory. Using a Reader on an not Unicode file can slow things down very much because of the need to convert the ASCII (or an other encoding as say, Latin1) to Unicode. If you don't need Strings, use Streams, not Readers.

Use profiling and compare the results because optimizing always gives surprising results (an optimization doesn't work at all and slows down and a small change elsewhere has an unexpected big benefit).

Cheers!
0
 
jerntatAuthor Commented:
Sorry for late reply, but thanks alot for your help, they are very helpful
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

  • 2
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now