CPerkins

package com.pragmaticsoftwaredevelopment.timingstringassembly;

import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Random;


public class TimingStringAssembly {
   String bigWodgeOfText;
   {
      Random rand = new Random();
      String characters=new String("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890`~!@#$%^&*()_+-=[]{};:',.<>/?| abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
      char[] buff = new char[100000];
      for (int ii=0; ii < buff.length; ii++)
         buff[ii] = characters.charAt(rand.nextInt(characters.length() -1));
      bigWodgeOfText = new String(buff);
   }

   public String randomLine (Random rand, int lineWidth) {
      int start = rand.nextInt(bigWodgeOfText.length()-lineWidth-1);
      String line = bigWodgeOfText.substring(start, start+lineWidth);
      return line;
   }

   public static String newline = System.getProperty("line.separator");
   public void justMakeTheRandomLines (int seed, int maxLines, int maxLineWidth) {
      Random rand = new Random(seed);
      int numLines = rand.nextInt(maxLines);
      int lineWidth = rand.nextInt(maxLineWidth);
      for (int ii=0; ii < numLines; ii++) {
         String randLine = randomLine (rand, lineWidth); // but will this be optimized away?
      }
   }
   public String viaStringBuilder (int seed, int maxLines, int maxLineWidth) {
      Random rand = new Random(seed);
      StringBuilder builder = new StringBuilder();
      int numLines = rand.nextInt(maxLines);
      int lineWidth = rand.nextInt(maxLineWidth);
      for (int ii=0; ii < numLines; ii++) {
         builder.append(randomLine (rand, lineWidth) + newline);
      }
      return builder.toString();
   }

   public String viaWriters(int seed, int maxLines, int maxLineWidth) {
      Random rand = new Random(seed);
      StringWriter stringWriter = new StringWriter();
      PrintWriter printWriter = new PrintWriter(stringWriter);
      int numLines = rand.nextInt(maxLines);
      int lineWidth = rand.nextInt(maxLineWidth);
      for (int ii=0; ii < numLines; ii++) {
         printWriter.println(randomLine (rand, lineWidth));
      }
      printWriter.flush();
      printWriter.close();
      return stringWriter.toString();
   }


   public void doit()
   {
      // WARMUP: call each method several times to make sure any optimizations have a chance to kick in:
      int warmupTimes = 1000;
      int seed=2317;
      int maxLines=100;
      int maxLineWidth=200;
      try {
         for (int jj=0; jj < warmupTimes; jj++) {
            FileWriter writer1 = new FileWriter ("C:\\temp\\junk_byBuilder");
            FileWriter writer2 = new FileWriter ("C:\\temp\\junk_byWriter");
            justMakeTheRandomLines (seed, maxLines, maxLineWidth);  // I do suspect this is optimized away, but it's here for comparison anyway
            writer1.append(viaStringBuilder (seed, maxLines, maxLineWidth));
            writer2.append (viaWriters (seed, maxLines, maxLineWidth));
            seed *= 2317;
            writer1.flush(); writer1.close();
            writer2.flush(); writer2.close();
         }
      } catch (IOException e) {
         String msg = "IOException during warmup: [" + e.getLocalizedMessage() + "]";
         System.out.println (msg);
         e.printStackTrace();
         System.out.flush();
         System.exit(0);

      }

      // TESTING: Now, for the money
      int numberOfLoops=1000;
      int numberOfTestsPerLoop=100;
      int totalTests = numberOfLoops * numberOfTestsPerLoop;

      long totalMsJustCreate=0;
      long totalMsByStringBuilder=0;
      long totalMsByWriters=0;
      try {
         for (int jj=0; jj < numberOfLoops; jj++) {
            System.out.println ("looptop " + jj);
            FileWriter writer1 = new FileWriter ("C:\\temp\\junk_byBuilder");
            FileWriter writer2 = new FileWriter ("C:\\temp\\junk_byWriter");

            for (int ii=0; ii < numberOfTestsPerLoop; ii++) {
               long start = System.currentTimeMillis();
               justMakeTheRandomLines (seed, maxLines, maxLineWidth);  // I do suspect this is optimized away, but it's here for comparison anyway
               totalMsJustCreate += (System.currentTimeMillis() - start);
            }
            for (int ii=0; ii < numberOfTestsPerLoop; ii++) {
               long start = System.currentTimeMillis();
               writer1.append(viaStringBuilder (seed, maxLines, maxLineWidth));
               totalMsByStringBuilder += (System.currentTimeMillis() - start);
            }
            for (int ii=0; ii < numberOfTestsPerLoop; ii++) {
               long start = System.currentTimeMillis();
               writer2.append (viaWriters (seed, maxLines, maxLineWidth));
               totalMsByWriters += (System.currentTimeMillis() - start);
            }
            seed *= 2317;
            writer1.flush(); writer1.close();
            writer2.flush(); writer2.close();
         }
         System.out.println ("After the testing (" + totalTests + " of each method), we see that it took:");
         System.out.println ("    " + totalMsJustCreate + " ms to simply create the random strings (probably optimized away)");
         System.out.println ("    " + totalMsByStringBuilder + " ms to assemble the random strings into one using StringBuilder");
         System.out.println ("    " + totalMsByWriters + " ms to assemble the random strings into one using PrintWriter(StringWriter)");
      } catch (IOException e) {
         String msg = "IOException: [" + e.getLocalizedMessage() + "]";
         System.out.println (msg);
         e.printStackTrace();
         System.out.flush();

      }


   }

   public static void main(String[] args)
   {
      TimingStringAssembly timer = new TimingStringAssembly();
      timer.doit();
   }
}