map

问题 Is it possible to have multiple values for the same key in a hash table? If not, can you suggest any such class or interface which could be used? 回答1: No. That's kind of the idea of hash tables. However, you could either roll your own with a Map<YourKeyObject, List<YourValueObject>> and some utility methods for creating the list if it's not present, or use something like the Multimap from Google Collections. Example: String key = "hello"; Multimap<String, Integer> myMap = HashMultimap.create(

问题 My client would like me to implement geolocation in a mobile application. He want me to use a map which is quite deformed (definitely not a google-like map). Is it an easy way to transform the GPS coordinates into the coordinates on that deformed map? I get the coordinates (X0,Y0) from the GPS -> I need the location on my client's map (X1,Y1) 回答1: Dude, you should try http://trimaps.com. It does exactly what you are looking for! 回答2: You need to know the mapping from the client map to real

问题 I was wondering how Java orders items in the Map ( HashMap or Hashtable ) when they are added. Are the keys ordered by the hashcode, memory reference or by allocation precedence...? It's because I've noticed same pairs in the Map are not always in the same order 回答1: java.util.HashMap is unordered; you can't and shouldn't assume anything beyond that. This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.

问题 I have a problem that I could not understand, I'm using a library for the use of Map Open Source Map (https://github.com/route-me/route-me), the example works perfectly, and I believe not to be something connected to the code , I believe it is something in the configuration. Well what happens is that if I make the following call: RMMarkerManager *markerManager = [mapView markerManager]; I get an error that says the UIView class does not have the method markerManager: 2013-08-05 17:18:33.573

问题 I have a problem that I could not understand, I'm using a library for the use of Map Open Source Map (https://github.com/route-me/route-me), the example works perfectly, and I believe not to be something connected to the code , I believe it is something in the configuration. Well what happens is that if I make the following call: RMMarkerManager *markerManager = [mapView markerManager]; I get an error that says the UIView class does not have the method markerManager: 2013-08-05 17:18:33.573

问题 I'm trying to make a procedure called map-odd-mapper where I take a proc that can then be applied to a list ex: ((make-odd-mapper add-one) (list 14 38 29 10 57)) (15 30 58) I was thinking of putting it as a let function as in (define (make-odd-mapper f) (let (..........something using ret-odds to allow for the indices so that you can get the odd numbers.... ret-odds is defined as (define (ret-odds lst) (if (null? lst) null (cons (car lst) (if (null? (cdr lst)) null (ret-odds (cdr (cdr lst))))

问题 I have a Rails 4 application. I have a search function with a select field. Now I'm getting this error: NoMethodeError: undefined method 'map' for "5":String: select * from users inner join user_texts on users.id = user_id where text_id = ? Here's view: <% form_tag user_path do <% select_tag :text_id, Option_from_collection_for_select(text.all, :id, :name, params[:text_id]), include_blank: true %> <%= button_to '#', class: 'btn btn-default' do %> <% t(:find) %> <% end %> Here's controller:

问题 I am using an std::map to store certain objects. The map has the template <Coordinate, Object> . Now, what I noticed is that the map casts the Coordinate to an integer, and then based on that gives the element a unique key. (Equal to that integer) Now, the problem is that it's impossible to convert a 3 dimensional integer (x, y, z) to a single integer, that the std::map can use. What alternatives are there to std::map which do require the key object to be unique, but don't require it to be

问题 I have a tree map with a following key value pair combination Map is declared as follows Map<String, List<Bean>> outputMap = new TreeMap<String,List<Bean>>(); Corresponding code will be for (String course_date : shiftSet) { Bean courseBean = null; boolean valueExists = false; for (Entry<String, List<Bean>> entry: courseMap.entrySet()){ valueExists = false; String studentDetail = entry.getKey(); String [] studentSet = StringUtils.getArray(studentDetail , ","); String studentId = studentSet[0];

问题 I have another question for you: The code below does the following For each file in a folder Open the file and read its contents Take and divide each line into tokens Save each token (word) in a hasMap Prepare a database query (Select form words ...) For each match found between the tokens and the words contained in the database Write 1.0, if true, otherwise 0.0; The problem arises at this point : try{ while (rs_mail.next()) { if(result_m.contains(rs_mail.getString("voc_w").toString())) /