Package com.puppycrawl.tools.checkstyle.checks

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 (the line with 'No newline at end of file' should not be in the 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

    • Method Detail

      • setLineSeparator

        public void setLineSeparator​(java.lang.String lineSeparatorParam)
        Setter to specify the type of line separator.
        Parameters:
        lineSeparatorParam - The line separator to set
        Throws:
        java.lang.IllegalArgumentException - If the specified line separator is not one of 'crlf', 'lf', 'cr', 'lf_cr_crlf' or 'system'

      • readAndCheckFile

        private void readAndCheckFile​(java.io.File file)
                       throws java.io.IOException
        Reads the file provided and checks line separators.
        Parameters:
        file - the file to be processed
        Throws:
        java.io.IOException - When an IO error occurred while reading from the file provided

      • endsWithNewline

        private static boolean endsWithNewline​(java.io.RandomAccessFile file,
                                       LineSeparatorOption separator)
                                throws java.io.IOException
        Checks whether the content provided by the Reader ends with the platform specific line separator.
        Parameters:
        file - The reader for the content to check
        separator - The line separator
        Returns:
        boolean Whether the content ends with a line separator
        Throws:
        java.io.IOException - When an IO error occurred while reading from the provided reader