The page I am working on has a javascript function executed to print parts of the page. For some reason, printing in Safari, causes the window to somehow update. I say somehow, because it does not really refresh as in reload the page, but rather it starts the "rendering" of the page from start, i.e. scroll to top, flash animations start from 0, and so forth. The effect is reproduced by this fiddle: http://jsfiddle.net/fYmnB/ Clicking the print button and finishing or cancelling a print in Safari causes the screen to "go white" for a sec, which in my real website manifests itself as something "like" a reload. While running print button with, let's say, Firefox, just opens and closes the print dialogue without affecting the fiddle page in any way. Is there something with my way of calling the browsers print method that causes this, or how can it be explained - and preferably, avoided? P.S.: On my real site the same occurs with Chrome. In the ex
If a key has two values...
ReplyDeleteIn a HashMap, a key cannot have two values. If you call map.put(key,value) with an existing key, the old value is removed from the map, and is returned by put().
One way to have multiple values per key is by using HashMap<K,Collection<V>>. This automatically provides the functionality you want, since you can simply examine the contents of the value collection after you've added the new element to it.
There are also third-party classes that provide this functionality, such as MultiValueMap.
edit:
If you're talking about multiple keys ending up in the same bucket, then you need to modify HashMap's put() method:
public V put(K key, V value) {
if (key == null)
return putForNullKey(value);
int hash = hash(key.hashCode());
int i = indexFor(hash, table.length);
if (table[i] != null) {
// TODO: there's already something in this bucket
}
for (Entry<K,V> e = table[i]; e != null; e = e.next) {
...
(Add your code where the TODO line is.)
You'll need to make similar changes to putForNullKey() and other related methods, such as putForCreate().
If you're modifying the HashMap class then you should be able to find where the list of elements is chained off the hash array and detect when there's more than one in the chain.
ReplyDeleteHOWEVER, you'd better have a very good reason for modifying HashMap, AND you'd better change the package and name of the class (to something like com.my.company.HashMapWithCollisionStatistics) or risk the eternal wrath of everybody who comes behind you to maintain Java code in your group.
Just use MultiMap from google collections.
ReplyDeleteWhy you need to do that? If just want to check the collision then call hashcode() on the objects that you are trying to store in the hashmap without storing them.
ReplyDelete