postcode normalization.java

import java.util.regex.Matcher;
import java.util.regex.Pattern;


String normalizePostcode(String postcode, String country) {
    Map<String, List<String>> rules = new TreeMap<String, List<String>>() {{
        put("Netherlands",    Arrays.asList("(NL-)?(\\d{4})\\W*([A-Z]{2})",                      , "\$2\$3"));
        put("United Kingdom", Arrays.asList("(?i)([A-Z]{1,2}[0-9]{1,2}[A-Z]?)\\s*([0-9][A-Z]{2})", "\$1\$2"));
    }}
    Pattern pattern = Pattern.compile(rules.get(country).get(0));
    String replacement = rules.get(country).get(1);
    Matcher matcher = pattern.matcher(postcode);
    return matcher.replaceAll(replacement);
}

System.out.println();
System.out.println(normalizePostcode("1101 DL", "Netherlands"));
System.out.println(normalizePostcode("1101-DL", "Netherlands"));
System.out.println(normalizePostcode("b288qp",  "United Kingdom"));