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<h1 class="post-title">Regex Find and Replace in IntelliJ</h1>
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<span>Jul 15, 2017</span>
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<p>The other day I was preparing a CSV file for load into a PostgreSQL database.
The source file contained a datetime column in an unusual format (<code>'15JUL2017:00:00:00'</code>), which needed to be transformed to a compatible format (<code>'15-JUL-2017:00:00:00'</code>) before loading with the <code>\copy</code> CLI command.
Values representing many different days, months, and years were present in the thousands.</p>
<p><img src="/assets/intellij-regex/csv.png" alt="CSV Data" /></p>
<p>My usual IntelliJ tricks did not work.
The file was large (4000 lines), which meant batch editing with multiple carets by matching all occurrences would have been too slow.<br />
The pattern itself was easily findable by a regex (2 numeric characters, 3 non-numeric characters, 4 numeric characters), but the replacement string depends on the groups matched.</p>
<p>Turns out IntelliJ has a feature to deal with this.
In the replacement string, you can simply reference the match group via <code>$X</code> (where <code>X</code> is the group number, starting at 1).</p>
<p><img src="/assets/intellij-regex/solution.png" alt="Regex Find and Replace" /></p>
<p>In the end, a search regex of <code>(\d{2})(\D{3})(\d{4})</code> and a replacement string of <code>$0-$1-$2</code> can be used.
IntelliJ is full of useful features.
Hopefully this will come in handy for you one day.</p>
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