hashmap

Hashmap object saved in Cloud Firestore with field names as letters insted of informed names

由 大兔子大兔子 提交于 2019-12-11 16:23:25
问题 I'm programming a android app in Kotlin and having troubles with document add to Cloud Firestore. When testing the app in android studio AVD Emulator it goes alright and saves as expected, but when I'm testing from my phone, with the app installed from Google Play Store in beta mode, it changes the field names of maps to letters. I'm creating a hashMap in kotlin as below: val mapeamento: HashMap<String, Any?> = hashMapOf( "user_id" to userId, "data" to data, "hora" to hora, "local" to

How to parse a key - value based dictionary using Perl

由 ♀尐吖头ヾ 提交于 2019-12-11 14:53:41
问题 using Perl I get a key - value based dictionary from an API call. use strict; use warnings; use LWP::Simple; my $url = "http://example.com/?id=124341"; my $content = get($url); $content =~ s/ /%20/g; print $content; {"id":"85710","name":"jack","friends":["james","sam","Michael","charlie"]} how can I parse it to get the results as bellow? name : jack hist friend list : james sam Michael charlie Thanks! 回答1: use strict; use warnings; use JSON 'decode_json'; my $content = '{"id":"85710","name":

Java - how to remove duplicating entries from HashMap?

由 ☆樱花仙子☆ 提交于 2019-12-11 14:13:23
问题 I have a HashMap in Java: HashMap<String, Integer> meh = new HashMap<String, Integer>();` meh.put("one", 1); meh.put("one", 1); meh.put("one", 1); meh.put("two", 1); meh.put("two", 2); meh.put("three", 3); What I need is to remove duplicating entries ("one", 1) [when both key and value duplicate]. I searched and found only 'how to remove duplicating keys/values'. Can anyone help? 回答1: There is no need to do that, HashMap takes care of that automatically. What happens when you execute that

Json String contain integer value , while deserialize to HashMap, Integer convert into double values

由 可紊 提交于 2019-12-11 12:58:31
问题 public static void main(String[] args) { Gson g = new GsonBuilder() .setPrettyPrinting() .enableComplexMapKeySerialization() .serializeSpecialFloatingPointValues() .setLongSerializationPolicy(LongSerializationPolicy.DEFAULT) .setPrettyPrinting() //.registerTypeAdapter(HashMap.class, new HashMapDeserializer()) .create(); HashMap<Object, Object> h = new HashMap<Object, Object>(); h.put("num1", 10); h.put("num2", 20); h.put("num3", 20.0); h.put("num4", "<>"); h.put("num5", "~!@#$%^&*()_+=-`,.<>?

refresh listview when using hashmap

由 ╄→尐↘猪︶ㄣ 提交于 2019-12-11 12:38:25
问题 I have a multiline listview , implemented using hashmaps . I get my data from a database . I have another activity in which i am adding my items , which is being added to the database . Now when pressing the save button , the new added item should appear immediately in the listview which is implemented in a fragment . I can't figure out how to refresh the listview in this activity . here's my fragment implementing the listview : public View onCreateView(LayoutInflater inflater, ViewGroup

Why do we check hash if we are going to check equals anyways?

由 北城以北 提交于 2019-12-11 12:29:27
问题 If two objects are equal then hashcode must be same. Then why does the any check in HashMap do - if (e.hash == hash && ((k = e.key) == key || (key != null && key.equals(k)))) { Instead of simply if ((k = e.key) == key || (key != null && key.equals(k)))) { 回答1: If two objects are equal then hashcode must be same. In this case, take it the other way: "If hashcodes of two objects are different, they can't be equal" So, here we are simply short-circuiting the comparison using equals() by first

HashMap

由 断了今生、忘了曾经 提交于 2019-12-11 12:26:50
名字 问题 一、简介 优点： 缺点： 二、继承关系图 是浅拷贝 HashMap实现了Cloneable，可以被克隆，是浅拷贝。 HashMap实现了Serializable，可以被序列化。 HashMap继承自AbstractMap，实现了Map接口，具有Map的所有功能。 三、存储结构 四、源码分析 /* 介绍 HashMap是一个散列表。他存储的内容是键值对（key-value）映射 HashMap继承AbstractMap，实现了Map，Cloneable、Serializable接口 HashMap的实现是不同步的，也就是线程不安全的，他的key、value都可以为null HashMap的映射不是有序的 HashMap的实例有2个参数影响其性能：“初始容量”和“加载因子”。 容量：是哈希表中桶的数量，通常默认为8 加载因子：是哈希表在其容量自动增加之前可以达到多满的一种尺度。通常默认为0.75 rehash操作：当哈希表中的条目数超过了加载因子与当前容量的乘积时，则要对该哈希表进行rehash操作（即重构内部数据结构）。从而哈希表讲具有大约两倍的桶数 通常默认加载因子为0.75，这是在时间和空间成本上寻求一种折衷。加载因子过高虽然减少了空间开销，但是同时也增加了查询成本（时间成本）。在设置初始化容量的时候应该考虑到映射中所需的条目数及其加载因子

ListView displaying only the final element of a ArrayList(HashMap)

由 本小妞迷上赌 提交于 2019-12-11 12:25:11
问题 I have an activity class that gets a JSON string by making a query. I parsed the string into a ArrayList(HashMap(String, String)). I am passing this to a ListView. The problem I am facing is while displaying the elements of the ArrayList only the last element in the list is shown in the UI. i.e. if there are 3 elements in the list, the third element is shown thrice This is my Function. The "buglist" view has a ListView in it and R.id.text1/2/3 are basically TextViews. public class GetBugs

map pattern matching in Erlang, unexpected error (unbound)

由 回眸只為那壹抹淺笑 提交于 2019-12-11 12:03:41
问题 The code below is basically copied from J.A.'s book: -module(mapz). -export([count_chars/1]). count_chars(Str) -> count_chars(Str, #{}). count_chars([H|T], #{H := N}=X) -> % line that throws count_chars(T, X#{H := N+1}); count_chars([H|T], X) -> count_chars(T, X#{H => 1}); count_chars([], X) -> X. however, compiling it in the shell gives me 151> c(mapz). mapz.erl:7: variable 'H' is unbound error 152> I understand the importance of having H bound before it can be used for matching a key in a

Hashmap of Vectors in C++

由 早过忘川 提交于 2019-12-11 11:52:07
问题 I want to implement a hashmap of vectors in C++. Here is my code: #include <cstdlib> #include <string> #include <iostream> #include <vector> using namespace std; #include <ext/hash_map> using namespace __gnu_cxx; int main (int argc, char * const argv[]) { std::vector<int> v; hash_map<int, std::vector<int> > months; v.push_back(28); v.push_back(28); v.push_back(28); v.push_back(29); months["february"] = v; //error = invlalid conversion from const char* to int return 0; } The above code fails
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