for(String word : stringList) {
    patterns.add(Pattern.compile("\b(" + word + ")\b);
}

for(Pattern pattern : patterns) {
    Matcher matcher = pattern.matcher(myString);
    if(matcher.matches()) {
         myString = matcher.replaceAll("String[$1]");
    }
}

if(hashMap.get(matcher.group(1)) == null) {
    // Can't test if  is required. Used it here for safe measure.
    matcher.replaceAll("****");
 } else {
    matcher.replaceAll(hashMap.get(matcher.group(1));
 }

Pattern pattern = Pattern.compile("\b(" + String.join("|",stringList) + ")\b");

StringBuilder regex = new StringBuilder("\b(");
for (String word : stringList) {
    regex.append(Pattern.quote(word));
    regex.append("|");
}
regex.setLength(regex.length() - 1); // delete last added "|"
regex.append(")\b");
Pattern pattern = Pattern.compile(regex.toString());

Matcher m = pattern.matcher(myString);
StringBuilder out = new StringBuilder();
int pos = 0;
while (m.find()) {
    out.append(myString, pos, m.start());
    String matchedWord = m.group(1);
    String replacement = matchedWord.replaceAll(".", "*");
    out.append(replacement);
    pos = m.end();
}
out.append(myString, pos, myString.length());
myString = out.toString();

\b(<word1>|<word2>|...|<wordN>)\b

StringBuilder res = new StringBuilder("\b(");
boolean first = true;
for(String word : stringList) {
    if (!first) {
        res.append("|");
    } else {
        first = false;
    }
    res.append(word);
}
res.append(")\b");
Pattern p = Pattern.compile(res.toString());

public static void main(final String[] argc) throws Throwable {
    Config c;
    try(InputStream s = new FileInputStream("webapp/WEB-INF/logScanConfig.xml")) { c = (Config) JAXBContext.newInstance(Config.class).createUnmarshaller().unmarshal(s); }
    final LineContext[] a = c.rules.toArray(new LineContext[c.rules.size()]);
    final StringBuilder regex = new StringBuilder();
    for(int i=0;i<a.length;i++) {
        final LineContext e = a[i];
        final String p ="(^"+
                (e.modul == null?".*":e.modul)+" ; "+
                (e.code  == null?".*":e.code )+" ; "+
                (e.mesg  == null?".*":e.mesg )+" ; "+
                (e.level == null?".*":e.level)+" ; "+
                (e.regex == null?".*":e.regex)+"$)";
        if(regex.length()>0) regex.append("|");
        regex.append(p);
    }

    final Pattern pattern = Pattern.compile(regex.toString(), Pattern.DOTALL);
    final Matcher m = pattern.matcher("ISS ; 0025 ; 0008 ; I ; State Manager started");
    if(!m.matches()) {
        System.out.println("Not Found");
    } else {
        System.out.println("GroupCount: "+m.groupCount()+" A["+a.length+"]");
        for(int i=1;i<=m.groupCount();i++) {
            if(null != m.group(i)) {
                System.out.println("GROUP["+(i-1)+"]: "+m.group(i));
                System.out.println(a[i-1]);
            }
        }
    }
  }
}

<logScanConfig user="private.1" pass="private.2">
 <logUrls>
  <e>http://private.3:80/fetch/log</e>
  <e>http://private.4:80/fetch/log</e>
  <e>http://private.5:80/fetch/log</e>
 </logUrls>
 <rules>
  <e backlogTime='600' minCount='0' maxCount='0' modul='ART' code='0114' mesg='1007' level='E'><regex>.*ORA-27101: shared memory realm does not exist.*</regex></e>
  <e backlogTime='600' minCount='0' maxCount='0' modul='ISS' code='0098'             level='E'><regex>Insufficient memory .*</regex></e>
 </rules>
</logScanConfig>