This regular expression is for which type of strings

Question

How can I know that any particular regular expression matches which type of input? Like I want to know about \$\{([\w]+)\}. Which string will be matched by this regular expression?

Pattern placeholder = Pattern.compile("\\$\\{([\\w]+)\\}");
Matcher mat = placeholder.matcher("input");
while (mat.find()) {

}

[What does the regex mean](http://stackoverflow.com/questions/22937618/reference-what-does-this-regex-mean)? — Wiktor Stribiżew, Aug 27 '15 at 09:40
To know what a regex matches, go to [regex101.com](http://regex101.com) and type in something, modify, experiment, pay attention to the right-hand pane with explanation and read those hints carefully. — Wiktor Stribiżew, Aug 27 '15 at 09:46

score 2 · Accepted Answer · edited May 23 '17 at 12:15

2

It accepts E.L access type to variables:

${somethingHere}

As comemnted above, you can check that Reference for more info.

edited May 23 '17 at 12:15

Community

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answered Aug 27 '15 at 09:40

Fran Montero

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https://regex101.com/ is a nice website to debug regex – Muhammad Imran Tariq Sep 17 '15 at 12:12

score 2 · Answer 2 · answered Aug 27 '15 at 09:43

This will find any character within ${}

The \w metacharacter is used to find a word character.

A word character is a character from a-z, A-Z, 0-9, including the _ (underscore) character.

The other characters are escaped by \, \$ looks for a $ \{ looks for { and \} looks for }

The + token mean to repeat the character ([\w]) between one and unlimited times, as many times as possible.

This regular expression is for which type of strings

2 Answers2