Create a gist now

Instantly share code, notes, and snippets.

What would you like to do?
String#split() と Pattern#split() の性能を比較するデモコード。
package biz.k11i.demo;
import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.util.List;
import java.util.regex.Pattern;
public class StringSplitDemo {
public static void main(String[] args) {
if (args.length < 2) {
return;
}
final int LOOP_COUNT = 1000 * 1000 * 20;
String text = "The quick brown fox jumps over the lazy dog.";
String[] patterns = { " ", "\\s", "[ \\t\\n\\x0B\\f\\r]", " |\\t|\\n|\\x0B|\\f|\\r" };
String pattern = patterns[Integer.valueOf(args[1])];
if ("string".equals(args[0])) {
profileStringSplit(text, pattern, LOOP_COUNT);
} else {
profilePatternSplit(text, pattern, LOOP_COUNT);
}
List<GarbageCollectorMXBean> beans = ManagementFactory.getGarbageCollectorMXBeans();
for (GarbageCollectorMXBean b : beans) {
if ("PS Scavenge".equals(b.getName())) {
System.out.println(String.format("%s\t%s", b.getName(),b.getCollectionCount()));
}
}
}
public static void profileStringSplit(String text, String pattern, int loopCount) {
long begin, end;
begin = System.currentTimeMillis() + 1000;
while (System.currentTimeMillis() < begin) {
// do nothing
}
for (int i = 0; i < loopCount; i++) {
text.split(pattern);
}
end = System.currentTimeMillis();
System.out.println(String.format("text : %s, pattern : \"%s\"", text, pattern));
System.out.println(String.format("String#split()\t%d", end - begin));
System.out.println();
}
public static void profilePatternSplit(String text, String pattern, int loopCount) {
long begin, end;
begin = System.currentTimeMillis() + 1000;
while (System.currentTimeMillis() < begin) {
// do nothing
}
Pattern p = Pattern.compile(pattern);
for (int i = 0; i < loopCount; i++) {
p.split(text);
}
end = System.currentTimeMillis();
System.out.println(String.format("text : %s, pattern : \"%s\"", text, pattern));
System.out.println(String.format("Pattern#split()\t%d", end - begin));
System.out.println();
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment