Pair sorting list without using a card or games

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

Search for keywords in a HashMap with a user-entered string

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

What is the easiest way to store and load Javascript data?

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'] =

How to convert a string to a hash key

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

Intersection of a set with a Java twist

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

find the sequence in the hashmap

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

Perl uninitialized value in numeric code

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

What is the purpose of programming on an interface?

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<

Assigning Arrays as Keys and Values ​​on a Map

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

HashMap - Use custom data objects

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

Can not save a hashmap object to a file in android

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

Dictionary in Java using hashmap

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

read the text file and store it in hashmap. Then sort in order

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. t

Example of Java HashMap to avoid collisions

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

When to include what?

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

Problem with Maps in Java

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

Define operations on the map

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

Compress Java HashMap to send via RMI

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

Is a HashMap compatible with threads for different keys?

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