regex for pattern in java

Question

I need regex (named in code myRegex) which will match all functions (function1, function2, function3).

public static void main(String[] args) {

    String template = "f[0-9]"; // like f1, f2 etc
    String myRegex = "fun\\((" + template + "*)\\)"; //todo what regex?
    Pattern myPattern = Pattern.compile(myRegex);

    String function1 = "fun(f1)";
    String function2 = "fun(f1,f9)"; //myRegex don't match
    String function3 = "fun(f1,f9,f4)"; // myRegex don't match

    List<String> functions = Lists.asList(function1, function2, function3);
    for (String function : functions) {
        Matcher matcher = myPattern.matcher(function);
        while (matcher.find())
        {
            System.out.println(function + " match!");//works only for function1
        }
    }

}

Elements in brackets must be seperated by comma (,). It must work for other funcions with many arguments like :function4 = "fun(f1,f9,f4,f5,f7)";

Vedvyas Mohapatra · Accepted Answer · 2021-06-22 15:31:19Z

2

Please use below.

String myRegex = "fun\\((" + template + ",)*" + template + "?\\)";

If you want to cater to fun() as well - without any parameters, use below

String myRegex = "fun\\((" + template + ",)*(" + template + ")?\\)";

edited Jun 22, 2021 at 15:31

answered Jun 22, 2021 at 15:24

Vedvyas Mohapatra

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2 Comments

Vedvyas Mohapatra Over a year ago

And if you need to also factor for fun(), then you can use the updated solution as well..

Didier L Over a year ago

Note that the first regex also matches fun(f) while the second one also matches fun(f1,).

Tim Biegeleisen · Accepted Answer · 2021-06-22 15:28:17Z

1

Use the following regex pattern:

fun\(f[0-9](?:,f[0-9]){0,2}\)

This will match any function named fun() having between 1 and 3 f arguments. Your actual Java regex pattern should be defined as:

Pattern myPattern = Pattern.compile("fun\\(f[0-9](?:,f[0-9]){0,2}\\)");

edited Jun 22, 2021 at 15:28

answered Jun 22, 2021 at 15:16

Tim Biegeleisen

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1 Comment

Anabelle95 Over a year ago

Thanks, sorry for editing my post after your answer. (Until my edit it was correct answer)

Amal K · Accepted Answer · 2021-06-22 15:46:33Z

0

Regex

Use the following regex. It will also work if there are spaces between arguments or parentheses:

fun\s*\(\s*(?:f[0-9])?(?:\s*,\s*f[0-9])*\s*\)

Demo

https://regex101.com/r/hndzov/1

Java string

Pattern myPattern = Pattern.compile("fun\\s*\\(\\s*(?:f[0-9])?(?:\\s*,\\s*f[0-9])*\\s*\\)")

Explanation

Regex	Description
`fun`	Match exactly the characters `fun`
`\s`	Match any whitespace character
`\s*`	Match 0 or more whitespaces
`\(`, `\(`	Match opening and closing parentheses
`f`	Match character `f`
`[0-9]`	Match any digit from 0-9
`(?:)`	Make a group but don't capture it

Cons

Also matches a parameter list with a leading comma like fun(,f2, f3).

edited Jun 22, 2021 at 15:46

answered Jun 22, 2021 at 15:31

Amal K

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