Check String if it is java code

Question

I'm working on a large project so i need to write some code to make sure that people clear all comment code like:

//String a = "something";

I was googled for check if string is java code but i found nothing. Any suggestion? Thank for your support.

can you clarify? put some examples, also, where you have to use this code? — Jordi Castilla, Aug 12 '15 at 08:53
Existing code checking tools can probably handle this a lot better. — Kayaman, Aug 12 '15 at 08:54
for clarify: i need to check all the code that people commented like // *somejavacodehere* or /* "javacodehere" */ — Hash, Aug 12 '15 at 08:55
You want to [Minify](https://en.wikipedia.org/wiki/Minification_(programming)) your code, remove comments or just remove Java comments but keep human comments? — Jordi Castilla, Aug 12 '15 at 08:55
@Hash so you don't want to remove none java code lines like `//hello` ?? — Madhawa Priyashantha, Aug 12 '15 at 08:58
@FastSnail I think this is the point... remove just java commented lines, not the human comments that clarify the code — Jordi Castilla, Aug 12 '15 at 08:59
when coding there is some line of code people didn't use so they comment them and then forget to remove them. I want to remove that kind of comments — Hash, Aug 12 '15 at 08:59
@Hash .... but why? this is not javascript you wont get any improvements... — Jordi Castilla, Aug 12 '15 at 09:00
@Fast Snail you got my point, i just want to remove comment which is java code and don't want to remove none java code lines — Hash, Aug 12 '15 at 09:01
@Hash can you edit your question adding a comment that you don't want to remove — Madhawa Priyashantha, Aug 12 '15 at 09:01
If your code contains only `//` comments, then you probably check for `//` & `;` in the line which most probably will be java code but if it also contains multiline comments `/**/`, then you need to do some extra hardwork to make a code for this. — Harshit, Aug 12 '15 at 09:01
@Jordi Castilla i currently working with japanese people, and they really hard in code style — Hash, Aug 12 '15 at 09:02
@dotwav my project like 100k line of code so manually reviewing is impossible in gived amount of time. — Hash, Aug 12 '15 at 09:04
@Fast Snail i just want to remove commented java code and leave other comment — Hash, Aug 12 '15 at 09:05
@Sora i want to write small app that help me check comments code which is java code — Hash, Aug 12 '15 at 09:07
@dotwav thank you but i just want to remove comment which is java code — Hash, Aug 12 '15 at 09:12

score 2 · Answer 1 · answered Aug 12 '15 at 09:07

2

What you want to do is really hard to get:

You can detect java code parsing lines starting with // and detect comments.

But imagine:

// String = "my cat is blue" + 
//          "seems a smurffle" +
//          "and I love it";

Hoy will you determine 2nd line is human or java comment? by " that does not seem very handy...

I would recommend you to use some IDE plugin like UCDetector for Eclipse or try oracle plugin for NetBeans and remove unused comments and code with more safety.

answered Aug 12 '15 at 09:07

Jordi Castilla

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Also, it would be difficult to detect if contains multiline comments like `line1 - /*..... line2 abcd.....line3.....*/` In this case, line2 will remain undetected. – Harshit Aug 12 '15 at 09:10
Yup, i have been working for 6 hour and have no solution yet – Hash Aug 12 '15 at 09:14
2

or imagine that comments are mixed with code... like: `//Set test = new HashSet<>(); could be used here, for blah blah...`, or `//instead of a TreeSet, use Set test = new HashSet<>();` – vefthym Aug 12 '15 at 09:16
as Sum up we can start with an idea that check if String contains "//" in first place and ";" in the ends of line – Hash Aug 12 '15 at 09:23
@Hash yes, `string.contains("//");` with `string.endsWith(";");` will clean most part of Java lines, but you must be carefull because `//a human comment;` will be erased also, and you will have orphan lines after this process as pointed in my answer... I think if you start here and you combine it with [Sonar Qube](https://en.wikipedia.org/wiki/SonarQube) as [@hinneLinks](http://stackoverflow.com/users/5072526/hinnelinks) will be more precise and a good start for a nice Java tool :) – Jordi Castilla Aug 12 '15 at 10:07
1

also, you said you work with japanese people.... by chance ¿¿they comment in japanese?? this will make your work much easier.... – Jordi Castilla Aug 12 '15 at 10:11

hinneLinks · Answer 2 · 2015-08-12T09:20:37.373

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You can use a static code analyses Tool like SonarQube - they Check for problems by just looking at the code without running it, e.g. not closed Connections etc. There are plenty of so called rules, that check something.

There is also a rule (namend CommentedOutCodeLine) that detects uncommented code.

If you connect that to your continious integration system, you might be able to automate the process - eg. building the code, checking it and send out an email, if some uncommented code was found.

edited Aug 12 '15 at 09:20

answered Aug 12 '15 at 09:11

hinneLinks

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Totally agree on this! It's a code quality issue, so code quality measurement and detection beyond uncommented lines of code is a very good idea, especially for a "large project". – Mathias Begert Aug 12 '15 at 09:55

score 1 · Answer 3 · answered Aug 12 '15 at 09:04

1

... // ... ;

No 100% solution, but for java a final semi-colon is very decisive.

String withoutCommentedOutCode(String line) {
    String clean = line.replaceFirst("\\s*//.*;\\s*$", "");
    if (clean != line) { // Or clean.length() != line.length()
        Logger.getLogger(getClass().getName(), Level.INFO, "Commented code: {0}", line); 
    }
    return clean;
}

answered Aug 12 '15 at 09:04

Joop Eggen

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Thank you but i want to check all line which is commented out java code not just String code – Hash Aug 12 '15 at 09:25

score 1 · Answer 4 · edited May 23 '17 at 12:22

You can easily find commented lines on the code, but to find if it's java code is more complicated. Once you find a commented line, you can use a syntax checker and depending on the type of error it returns, find out if it's pure java code (no error returned), or "maybe" java code (depending on the error returned).

Check this code, it uses the compiler to check if the syntax is correct and returns the error: Syntax Checking in Java

Mathias Begert · Answer 5 · 2015-08-12T09:12:17.443

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The simplest way is to search for comments ending in a ;. Just use grep:

cd /to/your/project/root
grep "//.*;" -r *

If you don't have grep, install cygwin or babun.

edited Aug 12 '15 at 09:12

answered Aug 12 '15 at 09:09

Mathias Begert

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What about multiline comments `/**/` which is present in multiple lines. – Harshit Aug 12 '15 at 09:11
thank you, check for ";" in comment line will be my start point – Hash Aug 12 '15 at 09:27
@Harshit Yes, /* traditional comments */ will not be detected by this, you're right. – Mathias Begert Aug 12 '15 at 10:01

score 0 · Answer 6 · answered Aug 13 '15 at 03:36

0

I just do a little trick and it work with 99% accurate: -First i read line to line of code - Then i check: if((line.contains("//") && line.contains(";") || (line.contains("*/") && line.contains(";")) { Systems.out.print(line); }

answered Aug 13 '15 at 03:36

Hash

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Check String if it is java code

6 Answers6