concurrentmodification

问题 I have the following code which throws ConcurrentModificationException because I am using two different iterators on the same list and one of them is modifying the list. So, the second iterator throws the exception when reading the list because some other iterator has modified the list. List<Integer> list = new ArrayList<>(); populate(list);//A method that adds integers to list ListIterator<Integer> iterator1 = list.listIterator(); ListIterator<Integer> iterator2 = list.listIterator(); while

问题 Code: I have a HashMap private Map<K, V> map = new HashMap<>(); One method will put K-V pair into it by calling put(K,V) . The other method wants to extract a set of random elements from its values: int size = map.size(); // size > 0 V[] value_array = map.values().toArray(new V[size]); Random rand = new Random(); int start = rand.nextInt(size); int end = rand.nextInt(size); // return value_array[start .. end - 1] The two methods are called in two different concurrent threads . Error: I got a

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 3 years ago . I'm looking for a concurrent list that can maintain the insertion order. Does anyone have some good recommendation ? I look at some from guava e.g. SetFromMap, but they are deprecated in the new version. Thank you. 回答1: If you have mostly read operations, very few write operations and you don't have too much

问题 I am reading Java Concurrency in Practice, according to some java code in it, System.out.println() will led to ConcurrentModificationException . The code is below : private final Set<Integer> set = new HashSet<Integer>(); public synchronized void add(Integer i) {set.add(i); } public synchronized void remove(Integer i) {set.remove(i);} public void addTenThings() { Random r = new Random(); for (int i = 0; i < 10; i++) { add(r.nextInt()); } System.out.println("DEBUG: add ten elements to " + set

问题 I am testing an event system I am writing for a project. In said project and tests, I do not touch threads. Literally, I do not create a thread or do anything with threads. However, I am getting a ConcurrentModificationException. I understand that there are other situations in which this exception may be thrown. From the CME JavaDoc: Note that this exception does not always indicate that an object has been concurrently modified by a different thread. If a single thread issues a sequence of

问题 I am passing Arraylist of ParseObject , and then i am putting one one foreach loop to extract the items with a condition when user object is not equals to null. There are two problems which i am facing. 1. If i am doing the following lines of code by passing different data to another list and then pass that list in my adapter, i am getting random data with numbers for example: If on item # 1 the name is "MAC" then it is showing in item 3. ArrayList<ParseObject> checkRequestedNetArrayList =

问题 This question already has answers here : ConcurrentModificationException when adding inside a foreach loop in ArrayList [duplicate] (3 answers) What does List Iterator's add() method do to the iterator? (3 answers) Closed 5 years ago . I Have a scenario such like this List<String> xxx = new ArrayList for(String yyy : xxx){ for(String zzz:xyxy){ if(!zzz.equals(yyy)){ xxx.add(zzz); } } } But i get java.util.ConcurrentModificationException: null exception.Can anyone help me solve this issue.?

问题 Still learning the ropes with Groovy, this problem has tripped me up since last night. Not sure why it's throwing concurrentmod exception...(Java 1.6, Groovy 1.8.4) I have a list of keys... [1,2,3,4,5,6,7,8,9,10,11,12,13] I collate the list using a custom function partitionList(keys,3) I got from here (can't use java.List.Collate, not on 1.8.6) Now I've got a list of lists... [[0,1,2],[3,4,5],[6,7,8],[9,10,11],[12,13]] If the number of sub-lists created is odd, I remove the last sub list [12

问题 I am making a particle emitter. Every "Rendered" object is stored in a HashSet, and when there's lots of particles on the screen, the console spits out concurrent modification exceptions. I usually have a short lifetime on these particles so they get deleted after several seconds, but I am sure this could potentially be a problem in the future. How can I fix this? EDIT: Code: public class UpdatedManager { private static Set<Updated> updates = new HashSet<>(); private UpdatedManager() {}

问题 I have a normal Database call that gathers information from my database. i use these informations to create my objects ( CallQueue ) these objects are then added to a list and the list is then returned. Suddenly i discovered that my originally code did not work as intended because i created dublicates and so now i am trying to void that any dublicates are being created! But there is a problem! I am unable to loop through my list and check wether or not the object is already created! Here is