1 // Copyright 1996-1999, International Business Machines
2 // Corporation. All Rights Reserved.
3
4 package org.apache.log4j.performance;
5
6 import java.util.Date;
7
8 /**
9 Measure difference in performance of string concatenation versus
10 creating an anonymous string array.
11
12 <p>You should be able to see that anonymous string array
13 construction is significatnly faster than string concatenation. The
14 difference increases proportionally with the length of the strings
15 to be concatanated.
16
17 @author Ceki Gülcü
18 */
19 public class ConcatVsArray {
20
21
22 static
23 void Usage() {
24 System.err.println("Usage: java org.apache.log4j.performance.ConcatVsArray " +
25 "string1 string2 runLength\n" +
26 " where runLength is an integer.");
27 System.exit(1);
28 }
29
30 public static void main(String args[]) {
31
32 if(args.length != 3) {
33 Usage();
34 }
35
36 String s1 = args[0];
37 String s2 = args[1];
38 int runLength = 0;
39 try {
40 runLength = Integer.parseInt(args[2]);
41 }
42 catch(java.lang.NumberFormatException e) {
43 System.err.println(e);
44 Usage();
45 }
46
47 double micros;
48
49 String[] sa;
50 long before = new Date().getTime();
51 for(int i = 0; i < runLength; i++) {
52 sa = new String[]{s1, s2};
53 }
54 micros = (new Date().getTime() - before)*1000.0/runLength;
55 System.out.println("The anonymous array loop took around " + micros + " microseconds.");
56
57 String s;
58 before = new Date().getTime();
59 for(int i = 0; i < runLength; i++) {
60 s = s1 + s2;
61 }
62 micros = (new Date().getTime() - before)*1000.0/runLength;
63 System.out.println("The append loop took around " + micros + " microseconds.");
64
65 }
66 }
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