linkedhashmap

问题 This question already has answers here : Iterating through a Collection, avoiding ConcurrentModificationException when removing objects in a loop (24 answers) Why is a ConcurrentModificationException thrown and how to debug it (7 answers) ConcurrentModificationException despite using synchronized (3 answers) Closed 10 months ago . I'm using a Map object in my class that I've synchronized with Collections.synchronizedMap() for a LinkedHashMap like so: private GameObjectManager(){ gameObjects =

问题 I have used LinkedHashMap with accessOrder true along with allowing a maximum of 500 entries at any time as the LRU cache for data. But due to scalability issues I want to move on to some thread-safe alternative. ConcurrentHashMap seems good in that regard, but lacks the features of accessOrder and removeEldestEntry(Map.Entry e) found in LinkedHashMap . Can anyone point to some link or help me to ease the implementation. 回答1: I did something similar recently with ConcurrentHashMap<String

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: Iterating through a LinkedHashMap in reverse order How to traverse Linked Hash Map in a reverse order? Is there any predefined method in map to do that? I'm creating it as follows: LinkedHashMap<Integer, String> map = new LinkedHashMap<Integer,String>(); map.put(1, "one"); map.put(2, "two"); map.put(3, "three"); 回答1: List<Entry<Integer,String>> list = new ArrayList<>(map.entries()); for( int i = list.size() -1;

问题 I want them to do a custom iterator, for a wrapper set. ListIterator from(E elem) 回答1: Extend the implementation and add some façade methods 回答2: If you want a custom iterator for a Map , do need to use a LinkedHashMap (which iterates in the same order as entries are added). Just use a HashMap and override the entrySet() method: public class Map<K, V> extends HashMap<K, V> { public Set<K, V> entrySet() { return new HashSet<K, V>(super.entrySet()) { public Iterator<Map.Entry<K, V>> iterator ()

问题 I want them to do a custom iterator, for a wrapper set. ListIterator from(E elem) 回答1: Extend the implementation and add some façade methods 回答2: If you want a custom iterator for a Map , do need to use a LinkedHashMap (which iterates in the same order as entries are added). Just use a HashMap and override the entrySet() method: public class Map<K, V> extends HashMap<K, V> { public Set<K, V> entrySet() { return new HashSet<K, V>(super.entrySet()) { public Iterator<Map.Entry<K, V>> iterator ()

问题 The LinkedCaseInsensitiveMap is part of the Spring Framework and extends the LinkedHashMap The hierarchy goes like this: java.lang.Object java.util.AbstractMap java.util.HashMap java.util.LinkedHashMap org.springframework.util.LinkedCaseInsensitiveMap For information refer : https://docs.spring.io/spring/docs/3.2.4.RELEASE_to_4.0.0.M3/Spring%20Framework%203.2.4.RELEASE/org/springframework/util/LinkedCaseInsensitiveMap.html Now I have this code : List<HashMap<String, String>> l_lstResult =

问题 As specified in the javadoc for LinkedHashMap, insertion order is not affected if a key is re-inserted into the map but While running the below program,I notice that inserting the same key again in changing the access order. Map<Integer, String> map = new LinkedHashMap<Integer,String>(16, .75f, true); map.put(new Integer(1), "Ajay"); map.put(new Integer(2), "Vijay"); map.put(new Integer(3), "Kiran"); map.put(new Integer(4), "Faiz"); for(String value:map.values()){ System.out.println(value); }

问题 I am building a java webservice which receive a LinkedHashMap as argument. The LinkedHashMap collection has some elements inserted in the client side, but I received it empty in the webservice. 回答1: Avoid returning collections directly. Instead of returning a List<X> , return a JavaBean that has a List<X> in it. This will give you more detailed control over the marshalling anyway. Producing a Web Service with JAX-WS and JAXB See also: What happens to generic class in jax-ws webservice? 来源：

问题 What do I want? I want to retrieve the list of objects in their insertion order from Firebase Database. How am I adding the object to list in Firebase database? mRefUser.push().setValue(new MessageItem()); mRefUser.push().setValue(new MessageItem()); . . mRefUser.push().setValue(new MessageItem()); How is it getting added? Firebase stores each object as key value pair in HashMap. How am I retrieving these values? mFireBaseRefnew.addValueEventListener(new ValueEventListener() { @Override

问题 To sort it int ascending order I can use: myMap.entrySet().stream() .sorted(Map.Entry.comparingByValue()) .collect(Collectors.toMap(Entry::getKey, Entry::getValue)); How can I do it in decreasing order? 回答1: To sort in reverse order, pass Comparator.reverseOrder() as parameter to comparingByValue . To get a LinkedHashMap , you must specifically request one with the 4-argument toMap() . If you don't specify what kind of a map you want, you will get whatever the default is, which currently