RegexpSingleline.md

Pattern: Possible single line issue in file

Issue: -

Description

A check for detecting single lines that match a supplied regular expression. Works with any file type.

Rationale: This check can be used to prototype checks and to find common bad practice such as calling ex.printStacktrace(), System.out.println(), System.exit(), etc.

Examples

To configure the check to find trailing whitespace at the end of a line:

<module name="RegexpSingleline">
  <!-- \s matches whitespace character, $ matches end of line. -->
  <property name="format" value="\s+$"/>
</module>

To configure the check to find trailing whitespace at the end of a line, with some slack of allowing two occurrences per file:

<module name="RegexpSingleline">
  <property name="format" value="\s+$"/>
  <!-- next line not required as 0 is the default -->
  <property name="minimum" value="0"/>
  <property name="maximum" value="2"/>
</module>

An example of how to configure the check to make sure a copyright statement is included in the file:

<module name="RegexpSingleline">
  <property name="format" value="This file is copyrighted"/>
  <property name="minimum" value="1"/>
  <!--  Need to specify a maximum, so 10 times is more than enough. -->
  <property name="maximum" value="10"/>
</module>

Further Reading

• checkstyle - RegexpSingleline