LinkedHashMap will take more memory. Each entry in a normal HashMap just has the key and the value. Each LinkedHashMap entry has those references and references to the next and previous entries. There’s also a little bit more housekeeping to do, although that’s usually irrelevant.
The = sign is encoded to \u003d. Hence you need to use disableHtmlEscaping(). You can use Gson gson = new GsonBuilder().disableHtmlEscaping().create(); String s2 = gson.toJson(hm.toString()); For \/ turning into \\/ issue, the solution is s2.replace(“\\\\”, “\\”);
List<Map.Entry<String, Integer>> entries = new ArrayList<Map.Entry<String, Integer>>(map.entrySet()); Collections.sort(entries, new Comparator<Map.Entry<String, Integer>>() { public int compare(Map.Entry<String, Integer> a, Map.Entry<String, Integer> b){ return a.getValue().compareTo(b.getValue()); } }); Map<String, Integer> sortedMap = new LinkedHashMap<String, Integer>(); for (Map.Entry<String, Integer> entry : entries) { sortedMap.put(entry.getKey(), entry.getValue()); }
You can’t get the value of the Map based on index, Maps just don’t work that way. A workaround would be to create a new list from your values and get the value based on index. LinkedHashMap<String, List<String>> hMap; List<List<String>> l = new ArrayList<List<String>>(hMap.values()); l.get(0);
You could do this element adding to 1. or last place: Adding to last place ► You just need to remove the previous entry from the map like this: map.remove(key); map.put(key,value); Adding to first place ► It’s a bit more complicated, you need to clone the map, clear it, put the 1. value to it, … Read more
Let’s consider a constant stream of cache requests with a cache capacity of 3, see below: A, B, C, A, A, A, A, A, A, A, A, A, A, A, B, C, D If we just consider a Least Recently Used (LRU) cache with a HashMap + doubly linked list implementation with O(1) eviction time … Read more
According to the Javadocs, yes. This implementation differs from HashMap in that it maintains a doubly-linked list running through all of its entries. This linked list defines the iteration ordering, which is normally the order in which keys were inserted into the map (insertion-order). As for the edit, no, it should work just fine. But … Read more
You can use ObjectMapper.convertValue(), either value by value or even for the whole list. But you need to know the type to convert to: POJO pojo = mapper.convertValue(singleObject, POJO.class); // or: List<POJO> pojos = mapper.convertValue(listOfObjects, new TypeReference<List<POJO>>() { }); this is functionally same as if you did: byte[] json = mapper.writeValueAsBytes(singleObject); POJO pojo = mapper.readValue(json, … Read more
The semantics of LinkedHashMap are still those of a Map, rather than that of a LinkedList. It retains insertion order, yes, but that’s an implementation detail, rather than an aspect of its interface. The quickest way to get the “first” entry is still entrySet().iterator().next(). Getting the “last” entry is possible, but will entail iterating over … Read more
The Map interface provides three collection views, which allow a map’s contents to be viewed as a set of keys, collection of values, or set of key-value mappings. The order of a map is defined as the order in which the iterators on the map’s collection views return their elements. Some map implementations, like the … Read more