/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
import java.util.regex.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
    	System.out.println(regexMatcher("-0.501", "-?\\d*\\.?\\d++(?!i)"));
	}
	private static double regexMatcher(String s, String regex) {
	    Pattern pattern = Pattern.compile(regex);
	    Matcher matcher = pattern.matcher(s.replaceAll("\\s+", ""));
 
	    if (!matcher.find()) {
	        return 0;
	    }
	    String found = matcher.group();
 
	    return Double.parseDouble(matcher.group());
	}
}

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