RegEx for java variable

Question

I want to capture the java variable name in java file using regex. i am able to achieve one level where variable is assigned something , but if variable is not assigned anything then how to get it ?

My Regex : (\w*)<?>?\s*=(?=(?:[^"]|"[^"]*["])*$)
Click here for sample it should included both variable but not import class;

import java.io.File;
import java.io.IOException ;
String test="test";
String test22;
String includeThisAlso ;

it should match the variable but not import class.

Will this work for you? ^\s*(?:List\s*<)?\w+>?\s*\K\w+(?=\s*=|\s*;) — Julio
– Julio, Commented Aug 9, 2018 at 6:26
i replaced List in regex with any word , as it can be any class varaible .. ^\s*(?:\w*\s*<)?\w+>?\s*\K\w+(?=\s*=|\s*;) but can you please explain the regex also , what is the \K — Sandeep Chauhan
– Sandeep Chauhan, Commented Aug 9, 2018 at 6:52
In which environment or language you are going to use this regex? — revo
– revo, Commented Aug 9, 2018 at 7:03
@Julio also i just tried with java pattern , i think \K is not supported by java compiler.<br> regexplanet.com/share/index.html?share=yyyyy3ujp0r<br> also above regex is not matching private final String COMMENTS = "test"; — Sandeep Chauhan
– Sandeep Chauhan, Commented Aug 9, 2018 at 7:06

Julio · Accepted Answer · 2018-08-10 06:57:30Z

1

Try with this:

^\s*\w+(?:\s+\w+)*?(?:\s*<\w+>)?\s+(\w+)(?=\s*[=;])

Demo

Explained:

^ \s*              # Line starts with one or more spaces
  \w+              # a word (1 or more letters, numbers and '_')
  (?:\s+\w+)*?     # several extra words, separated by spaces. Ungreedy
  (?:\s*<\w+>)?    # Optional '<' + Word '>'
  \s+(\w+)         # Capture the variable with a group ()
  (?=\s*[=;])      # It must be followed by spaces and then '=' or ';'

Later on, you just need to reference the first capturing group. that will have the name of the variable

Editted to allow matching generics.

edited Aug 10, 2018 at 6:57

answered Aug 9, 2018 at 7:03

Julio

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7 Comments

Sandeep Chauhan Over a year ago

its not matching variable: private final String COMMENTS = "test";

Julio Over a year ago

Glad to hear. You may mark the answer as 'Accepted' if it worked for you.

Kartik Over a year ago

@Julio thanks for the answer. Your explanation doesn't match the updated pattern, can you please update it? particularly around (?:<\w+>)?

Julio Over a year ago

@Kartik Done! Thank you

Kartik Over a year ago

Thanks @Julio, upvoted. If you can modify it to make it work for generics, that would be awesome! private List<String> test;

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