modifying plain wikilinks in wikitext

wikilinks.java

public static String fixLinks(String src, Wiki target) {
    
    // add a marker to all the links so we can iterate through them (except the ones that point to wikipedia)
    String src2 = src.replaceAll("\\[\\[(?!(wikipedia))", "[[%");
    
    try {
        while (src2.contains("[[%")) {
            
            // extract the link text
            int a = src2.indexOf("[[%")+3;  // left inner bound
            int b = src2.indexOf("]]", a);  // right inner bound
            String link = src2.substring(a, b);
            
            // remove the label, if present
            int pipe = link.indexOf('|');
            link = (pipe == -1) ? link : src2.substring(a, a+pipe);

            // If the link does not exist (and is not a semantic wikilink or category), append 'wikipedia:'
            if (!link.contains("::") && !link.contains(":") && !link.contains("Category:") && !target.exists(link)[0]) {
                src2 = src2.substring(0, a-1) + "wikipedia:" + src2.substring(a);
            // else if it's not a special link (like File: or en:), make it a semantic link
            } else if (!link.contains(":")) {
                src2 = src2.substring(0, a-1) + "is_associated_with::" + src2.substring(a);
            // otherwise just remove the marker and move on
            } else {
                src2 = src2.substring(0, a-1) + src2.substring(a);
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
        return src;
    }
    return src2;
}