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I am using Vim to program in Java 8, and am having a problem with syntax highlighting.

A new feature in Java 8 is lambda support, which resulted in the creation of the arrow operator: ->. Vim does not recognize this as a valid operator in a *.java file. As such, it highlights this operator in bright red to draw attention to the "syntax error." (Of course, this really is valid syntax.)

Is there a way to update Vim's "dictionary" of allowed operators and/or fix the syntax highlighting to avoid this issue?

The first two lines of :version state:

VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Jan 2 2014 19:39:32)

Included patches: 1-52

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2016 update

The Vim syntax file was updated for this in v7.4.649 (March 2015); so if you have this patch you don't need to do this.

The easiest way to fix this is probably by downloading the newer syntax/java.vim file and putting it in ~/.vim/syntax/java.vim so it will override the default $VIMRUNTIME/syntax/java.vim. You will also need to symlink html.vim for this to work as java.vim depends on this:

ln -s /usr/share/vim/vim74/syntax/html.vim ~/.vim/syntax/

Original answer

My /usr/share/vim/vim74/syntax/java.vim has this:

syn match javaError "<<<\|\.\.\|=>\|||=\|&&=\|[^-]->\|\*\/"

See the [^-]-> part? That causes the error highlighting.

You can override this rule by adding a ~/.vim/after/syntax/java.vim file, with the same pattern minus the lambda syntax:

syn clear javaError
syn match javaError "<<<\|\.\.\|=>\|||=\|&&=\|\*\/"

And for bonus points, we can add this line to highlight this as a function:

syn match javaFuncDef "[^-]->"

Consider filing a bug report. :help bug-reports explains how. There seem to be more (new?) constructs that are highlighted as an error, such as the ... in public static void main(String... args).

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    The matching for the bonus points does not check if java_highlight_functions has been enabled. If you are neurotic about consistency, you should probably check it before the syn match call: if exists("java_highlight_functions") | syn match javaFuncDef "[^-]->" | endif
    – Zachary Murray
    Jul 14 '15 at 23:25
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It's not necessary to edit the default syntax file. The vim-java plugin has support for this. Just install like any other plugin and the lambda operator will be highlighted correctly.

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  • Are you sure? Because I don't see any code for it, and the only commit I see only removes the -> from javaError with the message "Don't match javaError if it's a lambda symbol" (but doesn't add highlighting as a function).
    – Martin Tournoij
    Mar 22 '16 at 18:56
  • @Caspetsmoker You're right. Just removes the error message. But I prefer like this.
    – adelarsq
    Mar 23 '16 at 14:10
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    I see that the runtime files have been updated in March 2015 btw, and that the repo you link to doesn't have many fixes that this updates introduces. FYI :-)
    – Martin Tournoij
    Mar 23 '16 at 14:18
  • @Carpetsmoker Nice. Did work as expected. Thanks =)
    – adelarsq
    Mar 23 '16 at 14:28

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