使用regex.pattern过滤列表

Question

I need to filter a list full of urls using regex.Pattern. For now I have this one for types.

private final static Pattern FILTERS_TYPE = Pattern.compile(".*(\\
(css|js|bmp|ico|gif|jpe?g" + "|png|tiff?|mid|mp2|mp3|mp4"
    + "|wav|avi|mov|mpeg|ram|m4v|pdf" + "|rm|smil|wmv|swf|wma|zip|rar|gz|jsp))$");

So I'm trying to write a filter to exclude sites like "facebook" , "twitter" ect.

private final static Pattern FILTERS_NAME =       Pattern.compile(".*facebook.*|.*quotidiani.*|.*meteo.*|.*twitter.*|.*hotel.*|.*mobile.*|"         + ".*histats:*"); 

but this one doesn't work. What is the correct syntax for "filters_name"?

private List<WebURL> trash = new ArrayList<>(); //non obiettivo
private List<WebURL> urls = new ArrayList<>(); //obiettivo



public synchronized void collectorUrls(){

    for(int i =0; i<urls.size();i++){
        String indirizzo = urls.get(i).getURL().toLowerCase();
        if(FILTERS_TYPE.matcher(indirizzo).matches()){

            trash.add(urls.get(i));
            urls.remove(i);

            }
        if(FILTERS_NAME.matcher(indirizzo).matches()){


            trash.add(urls.get(i));
            urls.remove(i);

            }
        System.out.println(urls.get(i).getURL());
        }   
}

Answer 1

Use this regex:

private final static Pattern FILTERS_NAME =  
         Pattern.compile("facebook|quotidiani|meteo|twitter|hotel|mobile|histats:"); 

Then replace Matcher.matches() method by Matcher.find() . So instead of:

if(FILTERS_NAME.matcher(indirizzo).matches()) {...}

Use:

if(FILTERS_NAME.matcher(indirizzo).find()) {...}

Answer 2

Oh, I think your problem is to remove items from the list while iterating.

The value of urls.size() will decrease when you remove a url from the urls list. The result is that the last urls in your list will never be checked.

Use an iterator for urls list in a while loop.

Explanation:

urls contains the string " http://facebook.com " and the string "meteo.com".

1. iteration step: i == 0 and urls.size() == 2

   string matches url-pattern and urls.remove(0) is called

2. iteration step: i == 1 and urls.size() == 1

   i is not smaller anymore than urls.size() -> leave for loop, second string in urls will not be checked