collections

问题 I have 2 views on top of my CollectionView and just want to scroll on all these 3 views. I understand the best approach is to place these 2 top views in my collectionView header. How can I achieve this in storyboard (interface builder) without any code? (I use this way in my another tableView but I have can't do this with CollectionoView) I drag those 2 views to my collectionView's reusableView(headerView) and I've faced with this error: enter image description here 回答1: There is no way you

问题 How can I make a List or similar Collection that represents a subset of another collection, masking (filtering out) unwanted elements but without creating an entirely new collection structure? The second list could then be more quickly modified by enabling/disabling the visibility of individual elements. Doing so should be more performant than constantly rebuilding a second separate collection structure. I imagine some kind of bit-map view into the original collection. Ideally this would be

问题 Is there any specific API which needs to be used? Could someone please post how it could be implemented. Any suggestion would be deeply appreciated. 回答1: This will depend upon your requirement which collection would be suitable, If it is list of String then use java.util.List or if it is set of String then use java.util.Set or it is also key-value pair then use Map . And implementation of each interface also specific to requirement. When you are talking about data amount then it comes with

问题 In Java I've two lists: List<Satellite> sats = new ArrayList<Satellite>(); List<Satellite> sats2 = new ArrayList<Satellite>(); Satellite sat1 = new Satellite(); Satellite sat2 = new Satellite(); sats.add(sat1); sats2.add(sat1); sats2.add(sat2); When I do the following containsAll method on the first list: sats.containsAll(sats2); //Returns TRUE! It returns true. But the first List (sats) only contains 1 item and the second list contains 2. Therefor it's not even possible that the first list

问题 I have two multimaps as below : ListMultimap<String, String> source_multimap = ArrayListMultimap.create(); ListMultimap<String, String> target_multimap = ArrayListMultimap.create(); for (SwiftTagListBlock s : source_tagListBlock) { Iterator<Tag> sourcetag_iterator = s.tagIterator(); while (sourcetag_iterator.hasNext()) { Tag tag = (Tag) sourcetag_iterator.next(); source_multimap.put(tag.getName(), tag.getValue()); } } for (SwiftTagListBlock t : target_tagListBlock) { Iterator<Tag> targettag

问题 I have a singleton class handling Subscribe and Unsubscribe requests from different clients running in different threads. The singleton contains a collection of Subscribers. Before adding or removing, the class needs to validate that the element hasn't already been added or deleted. Normally I would implement this using a List or a HashSet calling Contains before each operation, but if I want to use one of the new classes in the System.Collections.Concurrent namespace, the only option I see

问题 I'm trying to receive all available sensors on the system and sort them alphabetic according sensor name. I'm using Collections and Comparator as I found in this answer but I get UnsupportedOperationException error. The code: SensorManager sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE); List<Sensor> sensorList = sensorManager.getSensorList(Sensor.TYPE_ALL); Collections.sort(sensorList, new Comparator<Sensor>() { @Override public int compare(Sensor leftSensor, Sensor

问题 I have a nested collection in the form: HashMap<String, HashMap<String, List<String>>> errorList; Now I initialize it inline using double braces like this errorList.put(tempName, new HashMap<String, List<String>>() {{ put("upl", new ArrayList<String>() {{ add("Y"); add("Upload Success"); }}); }}); This lies in a foreach loop with the value of tempName changing in every iteration. I did this because i couldn't use instances of List<String> or HashMap<String,List<String>> because every time i

问题 I have a problem with my TreeView in a WPF application (Framework 3.5 SP1). It's a TreeVIew with 2 Levels of Data. I expand / collapse the items of the first level in a particular way (with a single mouse-click on the TreeViewItem). Again when I expand a first-level TreeViewItem, I add some second-level TreeViewItems to the group (it's an important detail, infact if I don't add the items the problem doesn't occur). All works good until the TreeView loses focus. If, for example, I expand the

问题 Can anyone explain how the memory allocation is done while invoking a method having list collection as parameter. Since the code snippet below though apparently seems to result same but it is not resulting same. So I would like to know the difference in both the method call in terms of memory allocation. using System; using System.Collections.Generic; namespace ListSample { class ListSampleClass { static void Main(string[] args) { List<int> i = new List<int>(); i.Add(10); i.Add(15);