Trying to add a collection of items into a hashmap of type String. I iterate over the collection and if the value isn't in the hashmap I add it to the map and if it is I increment the quantity by 1 instead of adding it again. Here is my code so far.
In HashMap, or anywhere where hashing technique is used, hashcode method is called on the object, to calculate a hash that is used to find the bucket where the Entry object is stored. The value returned by the hascode() method is not a memory locatio
I have a csv file with two columns like this: column1 column2 sachin@@@tendulkar@@@Ganguly cricket@@@India@@@players I want to convert it to a hash map which would be like this: sachin-> "cricket, India, players" tendulkar-> "cricket,
public Map<product, SortedMap<Date, ServiceInterval>> getServiceInterval( Contract pContract, BillCycle pBillCycle) { Map<product, SortedMap<Date, ServiceInterval>> returnMap = new HashMap<>(); List<product> productList
This question already has an answer here: Using java.util.Map in h:dataTable 3 answers Using JSF: Is it possible to iterate over a Map whose values contain Maps? I have a Map that looks like this: Map<String, Map<String, String>> myMap; I woul
I have a strange problem in which I have data in three columns of students as follows, Student InitDAte FinDate ABC 2/2/2016 5/5/2017 ABC 3/2/2016 3/30/2017 CED 1/1/2015 3/12/2017 LEF 1/12/2016 11/17/2017 CED 1/12/1999 12/23/207 LEF 2/13/2000 11/19/2
I have a Java assignment where we are to program a "database" of books and journals using the ArrayList class to store them as objects of type Reference. One of the requirements from this assignment is that we split the titles of the books in th
I have a Hashmap for storing Loudness values. The code is in Javascript HTML5. var Loudness = {}; Loudness['f125'] = {right: [], left: []}; Loudness['f125']['right'].push([0,10,30, 40]); Loudness['f125']['left'].push([5,15,35,45]); Loudness['f250'] =
I need to convert a string (max. length = 20, consisting of random lower alphabetical characters and/or numbers) to a key for a hash table that holds slots for a max of 100.000 keys. What I tried is to convert each of the chars within the string to a
So I recently got the following question in a technical interview and I thought it was pretty interesting. Given two arrays: A = {1,2,2,4,5} and B = {1,2,6,} write code that performs the following two operations: A-B {2,4,5} and B-A {6}. Meaning, you
I am using Java to try make a check on my server side on whether or not what the user sends over is in the hashmap, but my example will run with the name I've given regardless of whether its in the hashmap or not. Anyone know why this is happening? c
I have a hashmap which represents [from, to]: 1st: [start->sb1] 2nd: [sb0->sb3] 3rd: [sb1->sb0] 4th: [sb3->end] I would like if there is a way to find the correct sequence such as: start->sb1->sb0->sb3->end Simple recursion can do
Why HashMap insert new Node on the index: tab[(n - 1) & hash] Where hash = key.hashCode() ^ key.hashCode() >>> 16 And n = tab.length of array of Node<K,V>. Why HashMap not put the Node just like that: tab[hash] ? Is it just another hash
my goal is to reduce memory usage. should I store a hashMap value in a variable if I need to use that value multiple times? public void upcCheck() { String prodUPC = pHashMap.get("productUpc"); if(prodUpc == ''){ //do stuff; } else if(prodUpc ==
I get these errors when i run this code I get these warnings that I really do not understand. When i change the == to a = i still get an error. : Use of uninitialized value in numeric eq (==) at ./pennies_again line 53, <$ogen_fh> line 2336 Use of u
This question already has an answer here: What does it mean to "program to an interface"? 30 answers I have surprisingly never understood the purpose of doing this: Map telephoneNumbers = new HashMap(); List<Object> list = new ArrayList<
I have two arrays of Type String: String [] a; String [] b; and then a map Map<String, String> mapNumeric = new HashMap<String, String>(); I want a to be the keys and b the value. So it will look like this: elementOfA = elementOfB otherElement
Suppose, I have a HashMap: HashMap<MyKey, Integer> HM = new HashMap<MyKey, Integer>(); MyKey corresponds to a data object with two integer elements (and a constructor for passing two integers). HM.put(new MyKey(1,1234), 1); // this seems to wo
I'm downloading lot of images from Internet and storing into a hashmap and showing in a ListView. I want to cache the images. For that, I am storing the Hashmap object into a file inside onDestroy() of my activity and getting back the object inside o
I am writing a little phone directory just to practice my knowledge about java. The problem is in the code below i want the code to display the name and the number whenever i call the getname method. I am a beginner and i really wish to make this pro
File is like this: name1 134.2 name2 456.7 name3 265.3 ... ... I read the text file and store in HashMap after that I want to sort in order(by the highest value) but the problem is that because I sort the values in String, I cant compare it. So..is t
I am using HashMap in java to store key and Object <Key,Object>. And I read about hashmap collision and I am trying to avoid it by using linked list. I did some search online, but I couldn't find an example how to do this. Can somebody point me to a
I created a class Person (as the book says) to hold the name and last name of a person entered from the keyboard and then there is another class PhoneNumber which encapsulates the country code, area code and the number of a person as a String. Person
I have a Hashmap which has X number of elements I need to move this map into another map This is what my code looks like Map originMap = initialize(); Map destMap = new Hashmap (); int originMapSize = originMap.size(); Set<Map.Entry<K, V>> ent
How can one perform set operations on a HashMap, such as Collections.addAll()?Based on you comments to the questions asked I think what you really need is a Set not a Map. Try Set<String> mySet = new HashSet<String>(); mySet.addAll(...); Use m
We have a Client/Server application which communicates over RMI. The server sends HashMaps to the client. All works well, however when sending large HashMaps, transfer times can be slow. Is there any way to compress the HashMaps before sending, then
If I have two multiple threads accessing a HashMap, but guarantee that they'll never be accessing the same key at the same time, could that still lead to a race condition?In @dotsid's answer he says this: If you change a HashMap in any way then your
I had a HashMap<Node, Double> in Java which I'd use later on to retrieve the double associated with a node. I've tried to do boost::unordered_map<Node*, double> but I get a "error C2108: subscript is not of integral type" when I try
The put function works fine but the get function does not. Apparently I don't know the trick. >> X = [ 1, 2, 3]; >> M = java.util.HashMap; >> M.put(X,1); >> M.get([1,2,3]) ans = [] I have searched and read many posts but could not
Here's Pair.java import java.lang.*; import java.util.*; public class Pair<TYPEA, TYPEB> implements Comparable< Pair<TYPEA, TYPEB> > { protected final TYPEA Key_; protected final TYPEB Value_; public Pair(TYPEA key, TYPEB value) { Key_ =