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javainputstreambufferedreader
Altiano Gerung
Altiano Gerung

Reputation: 854

Chaining InputStream in Java

So i know that InputStream sees the data as raw data and Reader sees it as characters.

Buffered them will make things more efficient.

But how about chaining them like this:

InputStream in = new InputStream(...);
in = new BufferedInputStream(in);
Reader r = new InputStreamReader(in);
r = new BufferedReader(r);

Is this right?

Upvotes: 1

Views: 1535

Answers (2)

Altiano Gerung
Altiano Gerung

Reputation: 854

This kind of question already answered : https://stackoverflow.com/a/15799469/3480200

With some opinion from others i conclude that:

It's not ok to use buffered inside another buffered in my case. It's useless.

Upvotes: 1

user813853
user813853

Reputation:

In Java 7, Here is an example of application that simply read a file 4MB using BufferedReader and InputStreamReader combined to BufferedInputStream and compare the performance of reading of bout techniques under Java 7.

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class MainIO_Optimization {

    public static void main(String[] args) {

        BufferedInputStream bis = null;
        InputStreamReader isr = null;
        BufferedReader br = null;

        try {

            // ------ 1 ------ 
            bis = new BufferedInputStream(new FileInputStream(new File("data/dictionnaire.txt")));
            isr = new InputStreamReader(bis);
            // ------ 2 ---------------
            br = new BufferedReader(new FileReader("data/dictionnaire.txt")); 

            char[] buf = new char[10];


            // ****** Performance  *****

            // we get system time 
            long startTime = System.currentTimeMillis();
            // we simply read
            while( br.read(buf) != -1 );
            // print the time of execution  
            System.out.println("Time reading using BufferedReader with FileReader : "+ (System.currentTimeMillis()-startTime) + " ms" );



            long startTime2 = System.currentTimeMillis();
            while( isr.read(buf) != -1 );
            System.out.println("Time reading using InputStreamReader with BufferedInputStream et FileInputStream : " + (System.currentTimeMillis() - startTime2 + " ms" ));


        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally{

            try {
                if(bis != null)
                    bis.close();
                if(isr != null)
                    isr.close();
                if(br != null)
                    br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }

}

The resultats

Time reading using BufferedReader with FileReader : 31 ms

Time reading using InputStreamReader with BufferedInputStream et FileInputStream : 32 ms

As you can see the result is 1 ms difference. BufferedReader is faster.

In Java 8 , you better use NIO package rather than IO. So FileChannels will be more efficient.

Upvotes: 1

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