Well I'm making a small phone book application and I've decided that using maps would be the best data structure to use but I don't know where to start. (Gotta implement the data structure from scratch - school work) ...
Are there any open source implementations of the following: given a set of keys and values, and a hash function, build up a hash table in a file image, such that it can then be mapped with a java.nio mapped file to avoid copying all the contents into virtual memory for lookups? ...
I want to get the following code to work in the Java ME / J2ME environment. Please help: Hashtable <Activity, Float>scores = new Hashtable<Activity, Float>(); scores.put(act1, 0.3); scores.put(act2, 0.5); scores.put(act3, 0.4); scores.put(act5, 0.3); Vector v = new Vector(scores.entrySet()); Collections.sort(v)...
I want to be able to create a fixed size hashmap of say 100 buckets, and if I need to store over 100 items then collisions and overwriting will just have to happen. The hashtable class has a IsFixedSize property however it is readonly. Am I thinking about this completely wrongly, or is there a solution to this? ...
Hello, I am using NSDictionary as an associated array (i.e, the keys i am using can be any arbitrary objects). One of the very annoying thing about NSDictionary is that it always make a copy of the key and store it. In my scenario, I will later retrieve the keys from the NSDictionary and do some operations with them. The operation happe...
Opened a LinkedHashSet source code today and found some interesting thing: public class LinkedHashSet<E> extends HashSet<E> implements Set<E>, Cloneable, java.io.Serializable { The question is: why do they need both "extends HashSet" and "implements Set" when HashSet already is the Set? ...
Hey hey, I am trying to wrap my head around C right now (mostly how pointers operate). I am trying to write this function described below: /* EnterName enter a Name into a symbol table. Returns a boolean indicating whether an entry for Name was already listed in the table. Passes back an argu...
Apparently, you cannot use a null for a key, even if your key is a nullable type. This code: var nullableBoolLabels = new System.Collections.Generic.Dictionary<bool?, string> { { true, "Yes" }, { false, "No" }, { null, "(n/a)" } }; ...results in this exception: Value cannot be null. Parameter name: key Descript...
I don't have experience with hash tables outside of arrays/dictionaries in dynamic languages, so I recently found out that internally they're implemented by making a hash of the key and using that to store the value. What I don't understand is why aren't the values stored with the key (string, number, whatever) as the, well, key, instead...
Hello, I know to read the contents of file in Objective-C, but how to take it as the input to hashtable. Consider the contents of text file as test.txt LENOVA HCL WIPRO DELL Now i need to read this into my Hashtable as Key value pairs KEY VAlue 1 LENOVA 2 HCL 3 WIPRO 4 DELL ...
Hello, Just before i had asked you about how to take input from file into hashtable by specifying key , i'm really sorry , actually i need to seperatly identify the key and value from text file and put it into my hashtable. i.e This is text file: LENOVA = Class_Name DELL = Class_Name WIPRO = Class_Name SAMSUNG = Class_Name Ineed to t...
Possible Duplicates: Hashtable in C++? can anybody offer a simple hash_map example in C++? Does the STL contain an implementation of a hashtable? If so, can you provide a brief example of how to use it? ...
I've doing some performance analysis on the software I develop, and I've found that lookups on a global dictionary of URL's takes about 10% of the application's "load" phase time. The dictionary is implemented as a C++ STL std::map, which has O(lg n) lookups. I'm going to move it to a hash_map, which has roughly fixed time lookups. Th...
What is Hashtables used for in Java? Further more please give examples of simple usage of Hashtables. ...
I have class Foo. Foo has a property of public string x. I would like to instantiate Foo a few times as ONE and TWO, and add those instances to Hashtable Bar with keys 1 and 2 respectively. How do I obtain string x for the particular instance. I've tried something to the like of: Bar[1].x, but the property x is not recognized. What...
I have a type of object called Bin, which has a hashtable field called Attributes. Like so: Public Class Bin Private _attributes As Hashtable Public Readonly Property Attributes() As Hashtable Get Return _attributes End Get End Property End Class If I have two bins, I'd like to compare if they...
I have implemented my own hash table functions in C, but currently it doesn't support resizing. I was wondering what algorithms do exist apart from the brute-force way of creating a new empty hash table and moving everything there? ...
What is the size (in bytes) of the Hashtable object in J2ME? I mean what is the overhead for using a Hashtable? ...
I am looking for opinions and best coding practices. I need to get info from a database with a query such as SELECT this, that FROM MyDB (returning 2 fields). Would it be wrong to use a hashtable for temporary storage? Is there a better way to accomplish the same thing? What about if I am returning more than 2 fields, would it be be...
Hello guys I have a problem ; I have some data and I show it with Hashtable for example I write : Enumeration keys; keys=CellTraffic_v.elements(); while(keys.hasMoreElements()) outputBuffer.append(keys.nextElement()+"\n\n"); but it show me just values how can i show values and keys together? for example this if my ke...