Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I threw together a totally unoptimized program based on your discarded regex approach and timed it. It completed in 650 ms (250 ms with warmup). The slowest part doesn't involve the regex, but <code>String.format</code>. If we replace it with a straight <code>StringBuilder</code> approach, the time drops to 40 ms.</p> <pre><code>public class Test { static Pattern regex = Pattern.compile("(..)(..)(..)(..)(..)(..)"); public static void main(String[] args) { final List&lt;String&gt; inMacs = new ArrayList&lt;&gt;(), outMacs = new ArrayList&lt;&gt;(); for (int i = 0; i &lt; 80_000; i++) inMacs.add(mac()); final long start = System.nanoTime(); for (String mac : inMacs) { final Matcher m = regex.matcher(mac); m.matches(); outMacs.add(String.format("%s:%s:%s:%s:%s:%s", m.group(1), m.group(2), m.group(3), m.group(4), m.group(5), m.group(6))); } System.out.println("Took " + (System.nanoTime() - start)/1_000_000 + " milliseconds"); final Iterator&lt;String&gt; it = outMacs.iterator(); for (int i = 0; i &lt; 100; i++) System.out.println(it.next()); } static Random rnd = new Random(); static String mac() { final long mac = (long) (rnd.nextDouble()*(1L&lt;&lt;48)); return String.format("%012x", mac).toUpperCase(); } } </code></pre> <p>If you are really looking for a fast solution, then avoid the regex and use a simple test to detect your MAC format:</p> <pre><code> static List&lt;String&gt; fixMacs(List&lt;String&gt; inMacs) { final List&lt;String&gt; outMacs = new ArrayList&lt;&gt;(inMacs.size()); for (String mac : inMacs) outMacs.add( mac.charAt(2) == '-'? mac.replace("-", ":") : mac.charAt(2) != ':'? fixMac(mac) : mac); return outMacs; } static String fixMac(String inMac) { final StringBuilder b = new StringBuilder(18); for (int i = 0; i &lt; inMac.length(); i++) { b.append(inMac.charAt(i)); if (i%2 == 1 &amp;&amp; i != inMac.length()-1) b.append(':'); } return b.toString(); } </code></pre> <p>With this approach I measured just 8 ms for your 80,000 MACs.</p>
    singulars
    1. This table or related slice is empty.
    1. POHow to convert MAC string to colon-separated string
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USMarko Topolnik
    1. USMarko Topolnik
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POHow to convert MAC string to colon-separated string
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThanks you @MarkoTopolnik, can't upvote, has only 3 pres
      singulars
      1. PO
      1. USsnaggs
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload