hashmap

问题 I tried adding functionality to the djb2 hash function, but it doesn't appear to like the changes. Specifically, I'm trying to include a loop that converts words (strings) to lower case. It throws the following two errors: Incompatible integer to pointer conversion assigning to char * from int Cannot increment value of type char *[45] Note that in the original code *str++ appeared in the while loop. This is my first hash table, and I'm rather shaky on pointers. Any insight on where I've gone

问题 I tried adding functionality to the djb2 hash function, but it doesn't appear to like the changes. Specifically, I'm trying to include a loop that converts words (strings) to lower case. It throws the following two errors: Incompatible integer to pointer conversion assigning to char * from int Cannot increment value of type char *[45] Note that in the original code *str++ appeared in the while loop. This is my first hash table, and I'm rather shaky on pointers. Any insight on where I've gone

问题 I have a ConcurrentHashMap that gets filled with put by 8 different Threads. One of the 8 Threads tries to read with a forEach consumer. My problem is, that the ConcurrentHashMap only has 5-7 entries. map.put(myContent); ... map.forEach(element -> ... do something); If I add a map.size() it for some reason shows all 8 entries map.put(myContent); map.size(); ... map.forEach(element -> ... do something); Going through the ConcurrentHashMap docs shows that it is not really thread-safe to iterate

问题 The containers package already contains functions to convert Set and List to Map but it's missing one for Vector from vector package. Is this because package developers do not want to have dependencies on other (similar) packages? Shouldn't be some general package which converts between data structures? In this way I always have to convert to List to convert to other structures. But I want to minimize use because of performance. 来源： https://stackoverflow.com/questions/41960585/how-to-create

问题 I have a NEAR smart contract that keeps a HashMap of Veggie records. My most basic accessor method get_veggie(vid), which looks up and returns one Veggie record, passes unit tests but fails in the deployed contract. It panics with 'veggie does not exist' when I send one of the keys returned by another accessor method, get_veggie_keys(). // this method returns an array of u64 keys: pub fn get_veggie_keys(&self) -> Vec<TokenId> { self.veggies.keys().cloned().collect() } // but this method

问题 I have read about the Hashmap collision and took the following example. Since i am not able to understand what is collision and how to avoid collision is occurs. The example is follows import java.util.*; class JavaCollision{ public static void main(String args[]){ HashMap<Person, String> map=new HashMap<Person, String>(); Person p1 = new Person(1,"ABC"); Person p2 = new Person(2,"DEF"); Person p3 = new Person(1,"XYZ"); Person p4 = new Person(1,"PQR"); Person p5 = new Person(1,"PQR"); System

问题 So I have this HashMap: HashMap<String,HashMap<Float,HashMap<Float,String>>> But I'm not to sure how to add and remove elements from the most deeply nest structure. Can someone give an example? Thanks :) Update: Thanks for the help, But how can I just put on the first level of the HashMap? I have tried .put and I am getting an error. Thanks 回答1: First create the map: HashMap<String, HashMap<Float,HashMap<Float, String>>> map = new HashMap<>(); Then put the first level map into it: map.put(

问题 In my algorithms class I've been told that a draw back of Adjacency Lists for graph representation is the O(n) look up time for iterating through the array of adjacent nodes corresponding to each node. I implement my adjacency list by using a HashMap that maps nodes to a HashSet of their adjacent nodes, wouldn't that only take O(1) look up time? Is there something I'm missing? 回答1: As you know look up for value using key in HashMap is O(1). However, in adjacency list the value of the HashMap

问题 I'm capturing parameters from a request url using com.apache.http.NameValuePair which basically store those params in List<NameValuePair> . To do certain checks and verifications on those params, I need to convert that list into a HashMap<String, String> . Is there a way to do this conversion? 回答1: Do you use Java 8? In that case you could make use of the Collectors.toMap() method: Map<String, String> mapped = list.stream().collect( Collectors.toMap(NameValuePair::getName, NameValuePair:

问题 I have map like Map<String,Integer> mp = new TreeMap<>(); mp.put("R1", 00); mp.put("R0", 11); mp.put("R2", 22); mp.put("R3", 33); mp.put("R5", 55); mp.put("R8", 88); mp.put("R4", 44); mp.put("R6", 66); mp.put("R9", 99); mp.put("R7", 77); mp.put("R11", 1111); mp.put("R14", 1414); mp.put("R10", 1010); mp.put("R12", 1212); mp.put("R13", 1313); mp.put("R15", 1515); mp.put("R17", 1717); mp.put("R19", 1919); I want to sort based upon keys. TreeMap is not working because of alphanumeric, getting