Using regex pattern in Java

Question

I created a regex pattern that works perfect, but I can't get it working in Java:

(\\"|[^" ])+|"(\\"|[^"])*"

applied to

robocopy "C:\test" "C:\test2" /R:0 /MIR /NP

gives (as it should)

[0] => robocopy
[1] => "C:\test"
[2] => "C:\test2"
[3] => /R:0
[4] => /MIR
[5] => /NP

in group 0 according to http://myregextester.com/index.php

Now, how do I get those 6 values in Java? I tried

Pattern p = Pattern.compile("   (\\\"|[^\" ])+  |  \"(\\\"|[^\"])*\"   "); 
Matcher m = p.matcher(command);

System.out.println(m.matches()); // returns false

but the pattern doesn't even match anything at all?

Update The original perl regex was:

(\\"|[^" ])+|"(\\"|[^"])*"

hmm compared to the original perl pattern (\\"|[^" ])+|"(\\"|[^"])*" I always added one back slash for string escaping. where do I need more? Thanks! Ah I think I got it. I have to double each, of course. — me.at.coding
– me.at.coding, Commented Aug 26, 2012 at 13:18

Sergey Kalinichenko · Accepted Answer · 2012-08-26 13:20:44Z

2

Since the regexp string is first processed by the compiler before making it to the regexp processor, you need to double every backslahs in the expression, and add additional slashes for every doublequote.

 Pattern p = Pattern.compile("(\\\\\"|[^\" ])+|\"(\\\\\"|[^\"])*\"");

answered Aug 26, 2012 at 13:20

Sergey Kalinichenko

729k85 gold badges1.2k silver badges1.6k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

amit Over a year ago

I think the original is already a regex, so for example \\" stands for a single backslash and a quote, which needs to be translated to \\\", as he did

Sergey Kalinichenko Over a year ago

@amit I think your interpretation is right, he meant for the regex engine to see \\" - a slash and a single quote. However, \\\" translates as \" after Java has its way with it, so you need two extra slashes.

amit · Accepted Answer · 2012-08-26 13:19:22Z

2

The matches() method is matching the whole string to the regex - it returns true only if the entire string is matching

What you are looking for is the find() method, and get the substring using the group() method.

It is usually done by iterating:

while (m.find()) { 
  .... = m.group();
  //post processing
}

answered Aug 26, 2012 at 13:19

amit

179k27 gold badges245 silver badges348 bronze badges

2 Comments

me.at.coding Over a year ago

Thank amit, also helpful, unfortunately I can only select one correct reply \:

amit Over a year ago

@stefan.at.wpf No problems, glad I could help. You should accept the solution the solved your problem, as you did. You can upvote an answer if you find it helpful - no limits on these:)

faradaj · Accepted Answer · 2012-08-26 13:22:35Z

0

matches() tries to match the pattern on entire string. You should use find() method of the Matcher object for your case.

So the solution is:

System.out.println(m.find());

answered Aug 26, 2012 at 13:22

faradaj

3,6891 gold badge24 silver badges21 bronze badges

Collectives™ on Stack Overflow

Using regex pattern in Java

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related