What's the fastest way to output a string to system out?

Question

I'm doing something like this:

for (int i = 0; i < 100000; i++) {    System.out.println( i ); } 

Basically, I compute an integer and output a string about 10K-100K times and then need to write the result to system.out, each result separated by a newline.

What's the fastest way to achieve this?

Answer 1

Thank you for the suggestions. I created a test program to compare them:

import java.io.BufferedOutputStream; import java.io.BufferedWriter; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.lang.StringBuilder;  public class systemouttest {      public static void main(String[] args) throws Exception {          long starttime = System.currentTimeMillis();         for (int i = 0; i < 100000; i++) {            System.out.println( i );         }         long printlntime = System.currentTimeMillis();          StringBuilder sb = new StringBuilder();         for (int i = 0; i < 100000; i++) {             sb.append( i + "\n" );         }         System.out.print(sb.toString());         long stringbuildertime = System.currentTimeMillis();          OutputStream out = new BufferedOutputStream ( System.out );         for (int i = 0; i < 100000; i++) {             out.write((i + "\n").getBytes());         }         out.flush();         long bufferedoutputtime = System.currentTimeMillis();          BufferedWriter log = new BufferedWriter(new OutputStreamWriter(System.out));         for (int i = 0; i < 100000; i++) {             log.write(i + "\n");         }         log.flush();         long bufferedwritertime = System.currentTimeMillis();          System.out.println( "System.out.println: " + (printlntime - starttime) );         System.out.println( "StringBuilder: " + (stringbuildertime - printlntime) );         System.out.println( "BufferedoutputStream: " + (bufferedoutputtime - stringbuildertime) );         System.out.println( "BufferedWriter: " + (bufferedwritertime - bufferedoutputtime) );     }  } 

Results:

Environment1
System.out.println: 482
StringBuilder: 210
BufferedoutputStream: 86
BufferedWriter: 202

Environment2
System.out.println: 1763
StringBuilder: 45
BufferedoutputStream: 76
BufferedWriter: 34

The suggestions all performed better than System.out.println. BufferedOutputStream seems to be the safest choice as it performed well in both test environments. BufferedWriter maybe faster though.

Please post further suggestions if anyone has some ideas. I'm sure someone can make it go faster :)

Answer 2

For large amount of data,System.out.println might be inefficient as it does not do very good buffering. In that case, you can use a BufferedOutputStream or a BufferedWriter.