Extract environment variable name from path in Java using regex [duplicate]

Question

I have to extract the value of an environment variable using a java method.

My path is ${rootPath}/user/settings and the value I want to get is rootPath.

I tried the following but it says "not match found":

Pattern.compile("\\$\\{(\\w+)\\}").matcher("${rootPath}/user/settings").group(1);

If I use the replace method it replaces the ${rootPath} value. What am I doing wrong?

You need to use the replaceAll() method in the right way :) — TheLostMind
– TheLostMind, Commented Jun 8, 2016 at 15:57
this is not the right approach use a suffix and substring, don't over use regexpr s.substring(0, s.length() - suffix.length()) — Nicolas Filotto
– Nicolas Filotto, Commented Jun 8, 2016 at 16:01

TheLostMind · Accepted Answer · 2016-06-08 15:56:23Z

1

Using replaceAll() would not be a bad idea IMHO and the code would look quite simple :):

public static void main(String[] args) {
    String s = "${rootPath}/user/settings";
    System.out.println(s.replaceAll("\\$\\{(.*?)\\}.*","$1"));
}

O/P :

rootPath

answered Jun 8, 2016 at 15:56

TheLostMind

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