Question

I was doing some research on IO and I read the following article which talks about buffering techniques. To minimize disk accesses and work by the underlying operating system, buffering techniques use a temporary buffer that reads data in a chunk-wise manner, instead of reading data directly from the disk with every read operation.

Examples were given without and with buffering.

without buffering:

try 
{ 
  File f = new File("Test.txt");
  FileInputStream fis = new FileInputStream(f);
  int b; int ctr = 0; 

  while((b = fis.read()) != -1) 
  { 
    if((char)b== '\t') 
    { 
      ctr++; 
    } 
  } 
  fs.close();
 // not the ideal way
 } catch(Exception e)
 {}

With buffering:

try
{
  File f = new File("Test.txt");
  FileInputStream fis = new FileInputStream(f);
  BufferedInputStream bs = new BufferedInputStream(fis);
  int b;
  int ctr = 0;
  while((b =bs.read()) != -1)
  {
    if((char)b== '\t')
    {
      ctr++;
    }
  }
  fs.close(); // not the ideal way
}
catch(Exception e){}

The conclusion was:

Test.txt was a 3.5MB  file 
Scenario 1 executed between 5200 to 5950 milliseconds for 10 test runs 
Scenario 2 executed between 40 to 62 milliseconds for 10 test runs.

Is there any other way to do this in Java that is better? Or any other method / technique to give better performance?Please advise..!

Answer 1

Is there any other way to do this in Java that is better? Or any other method / technique to give better performance?

In terms of IO performance, that probably is going to be the best without a lot of other code. You are going to be IO bound most likely anyway.

while((b =bs.read()) != -1)

This is very inefficient to read byte-by-byte. If you are reading a text file then you should be using a BufferedReader instead. This converts a byte array into String.

BufferedReader reader = new BufferedReader(new InputStreamReader(fis));
...
while ((String line = reader.readLine()) != null) {
   ...
}

Also, with any IO, you should always do it in a try/finally block to make sure you close it:

FileInputStream fis = new FileInputStream(f);
BufferedReader reader;
try {
    reader = new BufferedReader(new InputStreamReader(fis));
    // once we wrap the fis in a reader, we just close the reader
} finally {
    if (reader != null) {
       reader.close();
    }
    if (fis != null) {
       fis.close();
    }
}