java.util.regex.PatternSyntaxException：索引附近非法重复

Question

I am using Java8 and would like to use the following Regex to filter an address from a string, but I get this error:

Error

Exception in thread "main" java.util.regex.PatternSyntaxException: Illegal repetition near index 18
(\d+\s*(\w+ ){1,2}${(?i)\b(street|st|road|rd|avenue|ave|drive|dr|loop|court|ct|circle|cir|lane|ln|boulevard|blvd|way)\.?\b}(\s+${(?i)\b(apt|bldg|dept|fl|hngr|lot|pier|rm|ste|slip|trlr|unit|#)\.? *[a-z0-9-]+\b})?)|(${/P\.? ?O\.? *Box +\d+})
                  ^

Code

private static final String REGEX_ROAD = "(?i)\\b(street|st|road|rd|avenue|ave|drive|dr|loop|court|ct|circle|cir|lane|ln|boulevard|blvd|way)\\.?\\b";
private static final String REGEX_APT = "(?i)\\b(apt|bldg|dept|fl|hngr|lot|pier|rm|ste|slip|trlr|unit|#)\\.? *[a-z0-9-]+\\b";
private static final String REGEX_POBOX = "/P\\.? ?O\\.? *Box +\\d+";

private static final String REGEX_STREET = "(\\d+\\s*(\\w+ ){1,2}${"+REGEX_ROAD+"}(\\s+${"+REGEX_APT+"})?)|(${"+REGEX_POBOX+"})";

    input = input.replaceAll(REGEX_STREET, "<ADDRESS>");

Any help appreciated.

Entire Class:

package com.jobs.spring.service.replace;

public class ReplaceServiceImpl implements ReplaceService {

    private static final String REGEX_ROAD = "(?i)\\b(street|st|road|rd|avenue|ave|drive|dr|loop|court|ct|circle|cir|lane|ln|boulevard|blvd|way)\\.?\\b";
    private static final String REGEX_APT = "(?i)\\b(apt|bldg|dept|fl|hngr|lot|pier|rm|ste|slip|trlr|unit|#)\\.? *[a-z0-9-]+\\b";
    private static final String REGEX_POBOX = "/P\\.? ?O\\.? *Box +\\d+";

    private static final String REGEX_STREET = "(\\d+\\s*(\\w+ ){1,2}${"+REGEX_ROAD+"}(\\s+${"+REGEX_APT+"})?)|(${"+REGEX_POBOX+"})";

    @Override
    public String removePII(String input) {
        input = input.replaceAll(REGEX_STREET, "<ADDRESS>");
        return input;
    }

    public static void main(String[] args) {
        ReplaceService rep = new ReplaceServiceImpl();
        System.out.println(rep.removePII("1234 Flex Road and 21 happy street"));
    }
}

Answer 1

Java does not support string interpolation, the ${...} JavaScript-like template literal placeholders are not supported and are treated as literal symbols.

Since $ means the end of a string and is a zero-width assertion, it should not be quantified. However, Java regex engine is lenient to the user and allows the usage of a quantifier with a zero-width assertion (you may use ${5} although it makes no sense, there can only be a single end of a string at a given position).

The major problem here is that { (start of a limiting quantifier) must be followed with a number denoting the number of repetitions and if there is a symbol other than a digit, anything but a number followed with } or ,MAX_REPEATITION_VALUE} , the Illegal repetition error will show up.

So, just remove ${ and } .

String REGEX_STREET = "(\\d+\\s*(\\w+ ){1,2}"+REGEX_ROAD+"(\\s+"+REGEX_APT+")?)|("+REGEX_POBOX+")";

See the Java demo .