/* 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
	{
		String str = "#min({(((fields['example6'].value + fields['example5'].value) * ((fields['example1'].value*5)+fields['example2'].value+fields['example3'].value-fields['example4'].value)) * 0.15),15,9.087})";
		ArrayList<String> arL = new ArrayList<String>();
		String rx = "(?<=fields\\[['\"])[\\w\\s]*(?=['\"]\\])";
        Pattern ptrn = Pattern.compile(rx);
        Matcher m = ptrn.matcher(str);
        while (m.find()) {
            arL.add(m.group());
        }
        // Demo
        String[] arr = new String[arL.size()];
        arr = arL.toArray(arr);
        System.out.println(Arrays.toString(arr));
	}
}

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