hashmap

问题 I have a multi module maven project. In which I have initialized a static hashmap in a common module. I am inserting values in that hashmap in other module called controller and when I want to iterate that hashmap in third module then it gives null. Here is my static hashmap initialization: public static HashMap<String, Integer> hmSimultaneousRequestTracker = new HashMap<String, Integer>(); Controller module: Constants.hmSimultaneousRequestTracker.put(inputjson.getSettings().getUsername(),1);

问题 Trying to add values of same key but with iterating it. here is my array arr = [ {a: 10, b: 5, c: 2}, {a: 5, c: 3}, { b: 15, c: 4}, {a: 2}, {} ] Want to converted it like {a: 17, b: 20, c: 9} 回答1: Here is one way to do this by making use of Enumerable#reduce and Hash#merge: arr.reduce {|acc, h| acc.merge(h) {|_,v1,v2| v1 + v2 }} #=> {:a=>17, :b=>20, :c=>9} 回答2: each_with_object to the rescue: result = arr.each_with_object(Hash.new(0)) do |hash, result| hash.each { |key, value| result[key] +=

问题 Here is a working code example. Thanks to @markspace for providing me with it. The code here makes a hashmap and inserts values in it. public class RpgPersonExample { public static void main( String[] args ) { Map<String, RpgPerson> team = new HashMap<>(); team.put( "Sgt. Mayhem", new RpgPerson( 100, 10, 0 ) ); team.put( "Wizard", new RpgPerson( 100, 1, 10 ) ); team.put( "Dragon", new RpgPerson( 1000, 100, 100 ) ); System.out.println( team.get( "Dragon" ) ); System.out.println( team.get(

问题 I've a pair of state/city drop down selects in a form. The city drop down should be dynamically changed depending of the state selected by the user. I'm using jQuery with Spring MVC. My object of states/cities is a HashMap of HashMaps, so, for state '01' (first key), I've got cities 001 (second key) - city1 (value) and 002 (second key) - city2 (value): LinkedHashMap<String,LinkedHashMap<String, String>> enumsCountyByDistrict = new LinkedHashMap<String,LinkedHashMap<String, String>>();

问题 This doesn't work. Shouldn't it? class WeirdBean extends HashMap { public String inner = "set within" def getInner() { return this.inner } def getOuter() { return this.outer } } def o = WeirdBean.newInstance() o.outer = "set without" println o.getOuter() // set without println o.outer // set without assert o.outer == o.getOuter() // Pass println o.getInner() // set within println o.inner // null, even though public assert o.inner == o.getInner() // Fail, o.inner is null 回答1: Seems like Map:

问题 I will build a listview with images from the web. I've also asked an other question before: Android ListView with images from special hashmap. But now I tried to extend the SimpleAdapter. I use a hashmap to put the data. Then I use a new "ImageAdapter": public class ImageAdapter extends SimpleAdapter { public ImageAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String[] from, int[] to) { super(context, data, resource, from, to); // TODO Auto-generated constructor

问题 So I have a hashmap that has keys and objects. I was wondering if it was possible to create a number of permutations with the keys. So for example if i had: 1 - Object1 2 - Object2 3 - Object3 4 - Object4 To get a random order. So one outcome may be: 3 - Object3 1 - Object1 2 - Object2 4 - Object4 So far i have: Map<Integer, GeoPoint> mapPoints = new HashMap<Integer, GeoPoint>(); Map<Integer, GeoPoint> mapPointsShuffle = new HashMap<Integer, GeoPoint>(); for (int t =0; t < 50; t ++){

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 5 years ago . I'm trying to create an unordered_map where the key is of type char and the value is a pointer to my own custom class. Is this possible? Whenever I try compiling I get this among other errors: $ g++ -std=c++0x -o spellchecker spellchecker.cpp -lstdc++ spellchecker.cpp:17:27: error: template argument 2 is invalid

问题 How can I merge maps like below: val map1 = Map(1 -> "a", 2 -> "b") val map2 = Map("a" -> "A", "b" -> "B") After merged. Merged = Map( 1 -> List("a", "A"), 2 -> List("b", "B")) Can be List, Set or any other collection who has size attribute. 回答1: I'm not sure I understand what are you searching for exactly, but to achieve that for the provided example you could do: val map1 = Map(1 -> "a", 2 -> "b") val map2 = Map("a" -> "A", "b" -> "B") map1.mapValues(value => (value, map2(value))) However

问题 This question already has answers here : Closed 8 years ago . Got the solution.. Used linkedHashMap and was able to store the sorted key values in an array. Here's the link for the code. Possible Duplicate: store key values of sorted hashmap in string[] I created a hashmap and then 'sorted by value' the elements in the map using this code. The code worked and i was able to display on screen the key value pairs sorted by value. Now I want to store the keys(from the sorted elements) in a String