CODEWITHSUNDEEP
static-analysischeckstylepmd
Kalle Richter
Kalle Richter

Reputation: 8768

How to enforce multiple exception catchs in separate lines with checkstyle or PMD?

We're using checkstyle and PMD in our project and I'm looking for a way to enforce newlines between multiple catchs in one row, e.g.

} catch(IOException | IllegalArgumentException ex) {
    ...
}

should fail the validation whereas

} catch(IOException
        | IllegalArgumentException ex) {
    ...
}

should pass.

I'm not looking for alternatives like randomly working code formatters which introduce dependency on the IDE.

We're using checkstyle and PMD through Maven.

Upvotes: 0

Views: 50

Answers (1)

adangel
adangel

Reputation: 1910

A simple XPath-based rule for PMD could use this XPath expression:

<rule name="MultipleCatchTypesOnSeparateLines"
      language="java"
      message="Use a separate line for each catch type"
      class="net.sourceforge.pmd.lang.rule.XPathRule"
    <description>TODO</description>
    <priority>3</priority>
    <properties>
        <property name="xpath">
            <value>
<![CDATA[
//CatchStatement/FormalParameter[@SingleLine = true()]
]]>
            </value>
        </property>
        <property name="version" value="2.0"/>
    </properties>
</rule>

A more complex one, that would detect cases, where you have e.g. 3 catchs on 2 lines (which should be on three lines):

<rule name="MultipleCatchTypesOnSeparateLines"
      language="java"
      message="Use a separate line for each catch type"
      class="net.sourceforge.pmd.lang.rule.XPathRule"
    <description>TODO</description>
    <priority>3</priority>
    <properties>
        <property name="xpath">
            <value>
<![CDATA[
for $a in //CatchStatement/FormalParameter
  return for $b in (1 to count($a/Type))
    return $a[Type[$b][@BeginLine = $a/Type[$b + 1]/@BeginLine]]
]]>
            </value>
        </property>
        <property name="version" value="2.0"/>
    </properties>
</rule>

Please note: With PMD you cannot verify that the | character is on the next line. This token is not available in the AST.

Upvotes: 1

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