Question

I have a string like

(&(objectclass=${abc})(uid=${xyz}))

How can I search ${abc} and ${xyz} and replace with another strings. There can be any number of occurence of such substrings i.e.${abc} in main string. I was thinking of string.indexOf( but that could be messy. Any best approach?

${abc} will be replaced by another string abc. I will get them from some other parameters.

Answer 1

I would use String.indexOf(String sep, int start) in a loop repeatedly to copy text and values to a StringBuilder.

---

Something like

public static void main(String... args) throws IOException {
    Map<String, String> map = new LinkedHashMap<>();
    map.put("abc", "ABC");
    map.put("xyz", "XYZ");
    printSubstitue("nothing to change", map);
    printSubstitue("(&(objectclass=${abc})(uid=${xyz})(cn=${cn})(special='${'))", map);
}

private static void printSubstitue(String text, Map<String, String> map) {
    String text2 = subtitue(text, map);
    System.out.println("substitue( "+text+", "+map+" ) = "+text2);
}

public static String subtitue(String template, Map<String, String> map) {
    StringBuilder sb = new StringBuilder();
    int prev = 0;
    for (int start, end; (start = template.indexOf("${", prev)) > 0; prev = end + 1) {
        sb.append(template.substring(prev, start));
        end = template.indexOf('}', start + 2);
        if (end < 0) {
            prev = start;
            break;
        }
        String key = template.substring(start + 2, end);
        String value = map.get(key);
        if (value == null) {
            sb.append(template.substring(start, end + 1));
        } else {
            sb.append(value);
        }

    }
    sb.append(template.substring(prev));
    return sb.toString();
}

prints

substitue( nothing to change, {abc=ABC, xyz=XYZ} ) = nothing to change
substitue( (&(objectclass=${abc})(uid=${xyz})(cn=${cn})(special='${')), {abc=ABC, xyz=XYZ} ) 
     = (&(objectclass=ABC)(uid=XYZ)(cn=${cn})(special='${'))

---

It gets messy if you want to support nested ${ } values. 😉

abc123=ghi123
abc${xyz}=def${xyz}

(&(objectclass=${abc${xyz}})(uid=${xyz}))

I would suggest you keep it simple if you can. 😉