Class RegexpSinglelineCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable, FileSetCheck

    public class RegexpSinglelineCheck
    extends AbstractFileSetCheck

    Checks that a specified pattern matches a single line in 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.

    • Property format - Specify the format of the regular expression to match. Type is java.util.regex.Pattern. Default value is "$.".
    • Property message - Specify the message which is used to notify about violations, if empty then default (hard-coded) message is used. Type is java.lang.String. Default value is null.
    • Property ignoreCase - Control whether to ignore case when searching. Type is boolean. Default value is false.
    • Property minimum - Specify the minimum number of matches required in each file. Type is int. Default value is 0.
    • Property maximum - Specify the maximum number of matches required in each file. Type is int. Default value is 0.
    • Property fileExtensions - Specify the file type extension of files to process. Type is java.lang.String[]. Default value is "".

    To configure the default check:

     <module name="RegexpSingleline" />
     

    This configuration does not match to anything, so we do not provide any code example for it as no violation will ever be reported.

    To configure the check to find occurrences of 'System.exit(' with some slack of allowing only one occurrence per file:

     <module name="RegexpSingleline">
       <property name="format" value="System.exit\("/>
       <!-- next line not required as 0 is the default -->
       <property name="minimum" value="0"/>
       <property name="maximum" value="1"/>
     </module>
     

    Example:

     class MyClass {
          void myFunction() {
              try {
                 doSomething();
              } catch (Exception e) {
                 System.exit(1); // OK, as only there is only one occurrence.
              }
          }
          void doSomething(){};
     }
     
     class MyClass {
         void myFunction() {
             try {
                 doSomething();
                 System.exit(0);
             } catch (Exception e) {
                 System.exit(1); // Violation, as there are more than one occurrence.
             }
         }
         void doSomething(){};
     }
     

    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>
     

    Example:

     /**
     * This file is copyrighted under CC. // Ok, as the file contains a copyright statement.
     */
     class MyClass {
    
     }
     
     /** // violation, as the file doesn't contain a copyright statement.
     * MyClass as a configuration example.
     */
     class MyClass {
    
     }
     

    An example of how to configure the check to make sure sql files contains the term 'license'.

     <module name="RegexpSingleline">
         <property name="format" value="license"/>
         <property name="minimum" value="1"/>
         <property name="maximum" value="9999"/>
         <property name="ignoreCase" value="true"/>
         <!--  Configure a message to be shown on violation of the Check. -->
         <property name="message"
               value="File must contain at least one occurrence of 'license' term"/>
          <!--  Perform the Check only on files with java extension. -->
         <property name="fileExtensions" value="sql"/>
     </module>
     

    Example:

     /*
     AP 2.0 License. // Ok, Check ignores the case of the term.
     */
     CREATE DATABASE MyDB;
     
     /* // violation, file doesn't contain the term.
     Example sql file.
     */
     CREATE DATABASE MyDB;
     

    Parent is com.puppycrawl.tools.checkstyle.Checker

    Violation Message Keys:

    • regexp.exceeded
    • regexp.minimum
    Since:
    5.0
    • Field Detail

      • format

        private String format
        Specify the format of the regular expression to match.
      • message

        private String message
        Specify the message which is used to notify about violations, if empty then default (hard-coded) message is used.
      • minimum

        private int minimum
        Specify the minimum number of matches required in each file.
      • maximum

        private int maximum
        Specify the maximum number of matches required in each file.
      • ignoreCase

        private boolean ignoreCase
        Control whether to ignore case when searching.
    • Method Detail

      • setFormat

        public void setFormat​(String format)
        Setter to specify the format of the regular expression to match.
        Parameters:
        format - the format of the regular expression to match.
      • setMessage

        public void setMessage​(String message)
        Setter to specify the message which is used to notify about violations, if empty then default (hard-coded) message is used.
        Parameters:
        message - the message to report for a match.
      • setMinimum

        public void setMinimum​(int minimum)
        Setter to specify the minimum number of matches required in each file.
        Parameters:
        minimum - the minimum number of matches required in each file.
      • setMaximum

        public void setMaximum​(int maximum)
        Setter to specify the maximum number of matches required in each file.
        Parameters:
        maximum - the maximum number of matches required in each file.
      • setIgnoreCase

        public void setIgnoreCase​(boolean ignoreCase)
        Setter to control whether to ignore case when searching.
        Parameters:
        ignoreCase - whether to ignore case when searching.