Apache’s commons.collections library has a CollectionUtils class that provides easy-to-use methods for Collection manipulation/checking, such as intersection, difference, and union. The org.apache.commons.collections.CollectionUtils API docs are here.
Use drop to remove from the front and dropRight to remove from the end. def removeFirstAndLast[A](xs: Iterable[A]) = xs.drop(1).dropRight(1) Example: removeFirstAndLast(List(“one”, “two”, “three”, “four”)) map println Output: two three
The list is not modifiable, obviously your client method is creating an unmodifiable list (using e.g. Collections#unmodifiableList etc.). Simply create a modifiable list before sorting: List<String> modifiableList = new ArrayList<String>(unmodifiableList); Collections.sort(modifiableList, comparator);
There’s actually a Stack class: http://java.sun.com/j2se/1.5.0/docs/api/java/util/Stack.html If you don’t want to use that, the LinkedList class (http://java.sun.com/j2se/1.5.0/docs/api/java/util/LinkedList.html) has addFirst and addLast and removeFirst and removeLast methods, making it perfect for use as a stack or queue class.
You can give a try to Apache Commons Collections. There is a class CollectionUtils that allows you to select or filter items by custom Predicate. Your code would be like this: Predicate condition = new Predicate() { boolean evaluate(Object sample) { return ((Sample)sample).value3.equals(“three”); } }; List result = CollectionUtils.select( list, condition ); Update: In java8, … Read more
Yes, there are even behavioral and not just technical differences between the collections returned by the emptyXyz factory methods in the Collections class and the new of factory methods introduced in the interfaces (Map, List, Set) with JDK 9, if these are invoked with no arguments. The relevant difference is that the collections returned by … Read more
It just depends, do you want your users to be able to index into the data? If yes, use List. Both are interfaces, so you’re not leaking implementation details, really, you just need to decide the minimum functionality needed.
The correct and fast one-liner would actually be: while (map.values().remove(valueObject)); Kind of strange that most examples above assume the valueObject to be unique.
static final List<String> fruits = Arrays.asList(“APPLE”, “ORANGES”, “GRAPES”); if (fruits.contains(fruitname)) If your list was much larger, a set would be more efficient. static final Set<String> fruits = new HashSet<String>( Arrays.asList(“APPLE”, “ORANGES”, “GRAPES”, /*many more*/));
You can use find: Looks through each value in the list, returning the first one that passes a truth test (iterator), or undefined if no value passes the test. The function returns as soon as it finds an acceptable element, and doesn’t traverse the entire list. Using your example: var g = _.find(arr, function (x) … Read more