Add to hashmap takes a long time
java
Solution
The `hashCode()` method of `java.net.URL` performs DNS resolution. The `URL` class is unsuitable for use in a `HashSet` or as keys in a `HashMap`. Use either Strings or `java.net.URI`.
Here's some background:
- Michael Scharf: java.net.URL.equals and hashCode make (blocking) Internet connections....
- Eishay Smith: Java's URL little secret (which RobAu linked in a comment to this answer)
Problem
I've stuck by a few lines in my java program, which take too much time (about 20s), and it seems weird to me. Here are the lines ``` Map<URL, Integer> res2 = new HashMap<>(); for (URL url : res) { res2.put(url, null); } ``` Which res defined as following : ``` List<URL> res = new ArrayList<>(); ``` In my program, res.size() ~= 1500 Do you have any idea of where my problem could come from ? Thanks !