Class NewlineAtEndOfFileCheck

  • All Implemented Interfaces:
    Configurable, Contextualizable, FileSetCheck

    public class NewlineAtEndOfFileCheck
    extends AbstractFileSetCheck

    Checks whether files end with a line separator.

    Rationale: Any source files and text files in general should end with a line separator to let other easily add new content at the end of file and "diff" command does not show previous lines as changed.

    Example (line 36 should not be in diff):

     @@ -32,4 +32,5 @@ ForbidWildcardAsReturnTypeCheck.returnTypeClassNamesIgnoreRegex
     PublicReferenceToPrivateTypeCheck.name = Public Reference To Private Type
    
     StaticMethodCandidateCheck.name = Static Method Candidate
     -StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
     \ No newline at end of file
     +StaticMethodCandidateCheck.desc = Checks whether private methods should be declared as static.
     +StaticMethodCandidateCheck.skippedMethods = Method names to skip during the check.
     

    It can also trick the VCS to report the wrong owner for such lines. An engineer who has added nothing but a newline character becomes the last known author for the entire line. As a result, a mate can ask him a question to which he will not give the correct answer.

    Old Rationale: CVS source control management systems will even print a warning when it encounters a file that doesn't end with a line separator.

    Attention: property fileExtensions works with files that are passed by similar property for at Checker. Please make sure required file extensions are mentioned at Checker's fileExtensions property.

    This will check against the platform-specific default line separator.

    It is also possible to enforce the use of a specific line-separator across platforms, with the lineSeparator property.

    • Property lineSeparator - Specify the type of line separator. Type is com.puppycrawl.tools.checkstyle.checks.LineSeparatorOption. Default value is lf_cr_crlf.
    • Property fileExtensions - Specify the file type extension of the files to check. Type is java.lang.String[]. Default value is "".

    To configure the check:

     <module name="NewlineAtEndOfFile"/>
     

    Example:

     // File ending with a new line
     public class Test {⤶
     ⤶
     }⤶ // ok
     Note: The comment // ok is a virtual, not actually present in the file
    
     // File ending without a new line
     public class Test1 {⤶
     ⤶
     } // violation, the file does not end with a new line
     

    To configure the check to always use Unix-style line separators:

     <module name="NewlineAtEndOfFile">
       <property name="lineSeparator" value="lf"/>
     </module>
     

    Example:

     // File ending with a new line
     public class Test {⤶
     ⤶
     }⤶ // ok
     Note: The comment // ok is a virtual, not actually present in the file
    
     // File ending without a new line
     public class Test1 {⤶
     ⤶
     }␍⤶ // violation, expected line ending for file is LF(\n), but CRLF(\r\n) is detected
     

    To configure the check to work only on Java, XML and Python files:

     <module name="NewlineAtEndOfFile">
       <property name="fileExtensions" value="java, xml, py"/>
     </module>
     

    Example:

     // Any java file
     public class Test {⤶
     } // violation, file should end with a new line.
    
     // Any py file
     print("Hello World") // violation, file should end with a new line.
    
     // Any txt file
     This is a sample text file. // ok, this file is not specified in the config.
     

    Parent is com.puppycrawl.tools.checkstyle.Checker

    Violation Message Keys:

    • noNewlineAtEOF
    • unable.open
    • wrong.line.end
    Since:
    3.1