// Example 106 from page 79

//

import java.util.Random;

class Example106 {

public static void main(String[] args) {

if (args.length != 1)

System.out.println("Usage: java Example106 <length>\n");

else {

System.out.println("Timing character replacement, abusing a string buffer:");

Random rnd = new Random();

int length = Integer.parseInt(args[0]);

char[] cbuf = new char[length];

for (int i=0; i<length; i++)

cbuf[i] = (char)(65 + rnd.nextInt(26));

String s = new String(cbuf);

for (int i=0; i<10; i++) {

StringBuilder sb = new StringBuilder(s);

Timer t = new Timer();

replaceCharString(sb, 'A', "HA");

System.out.print(t.check() + " ");

}

System.out.println();

}

}

// In-place replacement in a StringBuilder; very inefficient and strange

static void replaceCharString(StringBuilder sb, char c1, String s2) {

int i = 0; // Inefficient

while (i < sb.length()) { // Inefficient

if (sb.charAt(i) == c1) { // Inefficient

sb.replace(i, i+1, s2); // Inefficient

i += s2.length(); // Inefficient

} else // Inefficient

i += 1; // Inefficient

} // Inefficient

}

// Simple timer, measuring wall-clock (elapsed) time in seconds

private final static class Timer {

private long start;

public Timer() {

start = System.nanoTime();

}

public double check() {

return (System.nanoTime() - start)/1e9;

}

}

}