Package com.puppycrawl.tools.checkstyle.checks.sizes

Class LineLengthCheck

java.lang.Object
com.puppycrawl.tools.checkstyle.api.AutomaticBean
com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck
com.puppycrawl.tools.checkstyle.checks.sizes.LineLengthCheck
All Implemented Interfaces:
Configurable, Contextualizable, FileSetCheck
public class LineLengthCheck extends AbstractFileSetCheck

Checks for long lines.

Rationale: Long lines are hard to read in printouts or if developers have limited screen space for the source code, e.g. if the IDE displays additional information like project tree, class hierarchy, etc.

  • The calculation of the length of a line takes into account the number of expanded spaces for a tab character ('\t'). The default number of spaces is 8. To specify a different number of spaces, the user can set TreeWalker property tabWidth which applies to all Checks, including LineLength; or can set property tabWidth for LineLength alone.
  • Package and import statements (lines matching pattern ^(package|import) .*) are not verified by this check.
  • Property fileExtensions - Specify file extensions that are accepted. Type is java.lang.String[]. Default value is "".
  • Property ignorePattern - Specify pattern for lines to ignore. Type is java.util.regex.Pattern. Default value is "^$".
  • Property max - Specify the maximum line length allowed. Type is int. Default value is 80.

To configure the check to accept lines up to 80 characters long: 

 <module name="LineLength"/>

To configure the check to accept lines up to 120 characters long: 

 <module name="LineLength">
   <property name="max" value="120"/>
 </module>

To configure the check to ignore lines that begin with " * " code, followed by just one word, such as within a Javadoc comment: 

 <module name="LineLength">
   <property name="ignorePattern" value="^ *\* *[^ ]+$"/>
 </module>

To configure the check to only validate java files and ignore other extensions: 

 <module name="LineLength">
   <property name="fileExtensions" value="java"/>
 </module>

To configure the check to only validate xml and property files and ignore other extensions: 

 <module name="LineLength">
   <property name="fileExtensions" value="xml, properties"/>
 </module>

Parent is com.puppycrawl.tools.checkstyle.Checker

Violation Message Keys:

  • maxLineLen
Since:
3.0

  • Field Details

    • MSG_KEY

      public static final String MSG_KEY
      A key is pointing to the warning message text in "messages.properties" file.
      See Also:

    • DEFAULT_MAX_COLUMNS

      private static final int DEFAULT_MAX_COLUMNS
      Default maximum number of columns in a line.
      See Also:

    • IGNORE_PATTERN

      private static final Pattern IGNORE_PATTERN
      Patterns matching package, import, and import static statements.

    • max

      private int max
      Specify the maximum line length allowed.

    • ignorePattern

      private Pattern ignorePattern
      Specify pattern for lines to ignore.

  • Constructor Details

    • LineLengthCheck

      public LineLengthCheck()

  • Method Details

    • processFiltered

      protected void processFiltered(File file, FileText fileText)
      Description copied from class: AbstractFileSetCheck
      Called to process a file that matches the specified file extensions.
      Specified by:
      processFiltered in class AbstractFileSetCheck
      Parameters:
      file - the file to be processed
      fileText - the contents of the file.

    • setMax

      public void setMax(int length)
      Setter to specify the maximum line length allowed.
      Parameters:
      length - the maximum length of a line

    • setIgnorePattern

      public final void setIgnorePattern(Pattern pattern)
      Setter to specify pattern for lines to ignore.
      Parameters:
      pattern - a pattern.