Why do you think this approach won’t be optimized? The reverse order Comparator is simply going to be flipping the sign of the output from the actual Comparator (or output from compareTo on the Comparable objects being inserted) and I would therefore imagine it is very fast. An alternative suggestion: Rather than change the order … Read more
Now let’s try some Java 8 code: static public Map<String, Integer> toMap(List<String> lst) { return lst.stream() .collect(HashMap<String, Integer>::new, (map, str) -> { if (!map.containsKey(str)) { map.put(str, 1); } else { map.put(str, map.get(str) + 1); } }, HashMap<String, Integer>::putAll); } static public Map<String, Integer> toMap(List<String> lst) { return lst.stream().collect(Collectors.groupingBy(s -> s, Collectors.counting())); } I think this … Read more
http://blog.firdau.si/2010/07/01/java-tips-initializing-collection/ List<String> s = Arrays.asList(“1”, “2”);
The problem in intList = new ArrayList<Integer>(Arrays.asList(intArray)); is that int[] is considered as a single Object instance since a primitive array extends from Object. This would work if you have Integer[] instead of int[] since now you’re sending an array of Object. Integer[] intArray = new Integer[] { 0, 1 }; //now you’re sending a … Read more
But how can we add strings to arraylist whose type has already been specified as Integer? Because of the way Java generics was designed for backwards compatibility, with type erasure and raw types, basically. At execution time, there’s no such things as an ArrayList<Integer> – there’s just an ArrayList. You’re using the raw type List, … Read more
removeEldestEntry always gets checked after an element was inserted. For example, if you override the method to always return true, the LinkedHashMap will always be empty, since after every put or putAll insertion, the eldest element will be removed, no matter what. The JavaDoc shows a very sensible example on how to use it: protected … Read more
I had this issue, but instead of using reflection, i ended up just checking if it was IEnumerable. All collections implement that. if (item is IEnumerable) { foreach (object o in (item as IEnumerable)) { } } else { // reflect over item }
Better option is use SQLQuery#addScalar than casting to Long or BigDecimal. Here is modified query that returns count column as Long Query query = session .createSQLQuery(“SELECT COUNT(*) as count FROM SpyPath WHERE DATE(time)>=DATE_SUB(CURDATE(),INTERVAL 6 DAY) GROUP BY DATE(time) ORDER BY time;”) .addScalar(“count”, LongType.INSTANCE); Then List<Long> result = query.list(); //No ClassCastException here Related link Hibernate javadocs … Read more
You should use the HashSet<T> class, which is specifically designed for what you’re doing.
You can do this: var coll = document.getElementsByTagName(‘div’); var arr = Array.prototype.slice.call( coll, 0 ); EDIT: As @Chris Nielsen noted, this fails in IE pre-9. Best would be to do some feature testing, and create a function that can handle either, or just do a loop as in the (second) solution from @brilliand.