IntelliJ IDEA custom postfix completion

I have no idea how could I possibly miss that one of my favorite features of IntelliJ IDEA is actually user-configurable. The postfix completion itself permits one to transform expression on the left side from the caret into different code block without jumping back and forth. One of the predefined completions is turning

co.nonnull<TAB>

into

if (co != null) {
    |
}

While this is pretty neat with plenty of predefined completions, adding custom is just an incredible productivity boost. Navigate to File > Settings > Editor > General > Postfix Completion to see what is available, and scratch the itch that has been bugging you for so long. It is a pity one can not explore how predefined completions are implemented, but it is fairly easy to get started without that.

Here is a couple of must-haves I added instantly:

$EXPR$.at -> org.hamcrest.MatcherAssert.assertThat($EXPR$, |);
$EXPR$.ae -> org.junit.Assert.assertEquals(|, $EXPR$);

As you can surely guess, IDEA will replace the $EXPR$ token with the expression being wrapped. None of this is really a discovery except for the fact, the official documentation does not mention how to declare desired caret position after the template has been applied. If left unspecified, the caret is placed behind the resulting declaration which is rarely the desired thing. Fortunately, the cure is mentioned in the announcement blog post for IDEA sibling project: PhpStorm.

So these are the declarations, applicable on non-void expressions, that will permit user to fill in the missing arguments right away:

org.hamcrest.MatcherAssert.assertThat($EXPR$, $END$);
org.junit.Assert.assertEquals($END$, $EXPR$);

So typing actual.ae<TAB>expected results into:

Assert.assertEquals(expected, actual);

Another shortcoming I have come across is, there appears to be no way to configure the completions to automatically add the static method import so it would actually result in my preferred style:

import static org.junit.Assert.assertEquals;

...

assertEquals(expected, actual);

Plugin to the rescue

The good news are, there is a Custom Postfix Templates plugin that offers lot more:

• Plenty of predefined completions that are sorted into groups so one can decide which to use and which to ignore. Not using Mockito? Not a problem, its completions can be hidden easily.
• Custom completions are declared in a text format and fed in as a local file or URL. The completions can be shared with the team and versioned. This is exactly how predefined completions are declared and distributed so they can be customized and studied.
• And of course, the expressions are more powerful.

With no intention to transcribe the project documentation, here is how our completions evolved:

.at : Hamcrest assertThat
  NON_VOID → org.hamcrest.MatcherAssert.assertThat($expr$, $expected$); [USE_STATIC_IMPORTS]

.ae : JUnit assertEquals
  NON_VOID → org.junit.Assert.assertEquals($expected$, $expr$); [USE_STATIC_IMPORTS]

The two completions, both with human readable description displayed in suggestion dropdown before use, are applicable in same context: non-void expression. With this plugin, in both cases, static method import is added and $expected$ parameter is where the caret is placed after application. From here it is all similar to Live Templates in supporting multiple variables and the smart navigation while entering them.

---

Tags: productivity java IDEA