I was wondering how to traverse through a hashtable. I am stuck on how to implement an iterator for the values of some hashtable.
Java Code:
public Iterator<V> values() {
return new Iterator<V>(){
@Override
public boolean hasNext() {
// TODO Auto-generated method stub
return false;
[Code] ....
I am very new to coding and I am struggling with one of my intro to Java Projects. This project involves creating a GUI that has a list of trees and their possible heights, giving each tree a range for their possible minimum and maximum heights.
I am having trouble creating this method for the TreeDatabase (TreeDB class):
public String queryByPossibleHeight(int key) Instructions for this method are as follows: this method creates and returns a single string that contains the trees that can be found such that the value key is in the range for possible height. Traverse the entire ArrayList of Trees and for each one of the trees contained in the ArrayList invoke the method inRange() from the class Tree. Pass to the method inRange() the parameter key. If inRange() returns true, invoke the method toString() from the class Tree. Append the value returned by invoking the method toString() to the String result, adding a “” at the end. Once the entire ArrayList has been traversed, return the String result.
My 3 classes so far (I haven't gotten to the actual GUI yet):
public class Range {
private int low;
private int high;
private int value;
public Range(int plow,int phigh){
low = plow;
high = phigh;
[Code]...
As you can see in the last TreeDB class, in the public String queryByPossibleHeight(int key) method I have something wrote in, but I was just testing random things.
I have to make a method called search that goes through the linked list and checks to see if whatever String the user entered matches a String in the linked list. With this code, every time I enter an existing String it outputs "There is no element that contains that information". How come?
public class LinkedListExample {
List InfoList = new LinkedList();
public void doLinkedListExample()
{ // add original data to linked list
InfoList.add("Computer"); // string (original 3 elements)
InfoList.add("Programs");
InfoList.add("in Java");
[code]....
I have a my result set object which has data as shown by the attached image.What i am trying to do is traverse these results and do certain operations. I want my program to do this, if I
View Replies View Related I have to make a program that allows the user to make a linked list of Strings (names) and then choose who to eliminate.
For example: Five people in a linked list of Strings: I would like the program to ask the user to choose a number between 1 and 5. If the user chooses number 2, Mary is the second person in the linked list so she gets eliminated.
The problem is that I'm not sure how to traverse through the linked list because they are of type String value, and I am looking for the name using the corresponding integer I mentioned above. I think I have to use Nodes? Not very sure where to start right now.Here is my code:
package llchallenge;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Scanner;
[code]...
AddItemToFront(Item p) : This method will create a new Node with the Item object as its data value and then add the newly created node to the front of the linked list.
DisplayItems(): This method will traverse the linked list from first node to last node and print data value ( i.e., id, name, type and price of the Item object) of each node.
RemoveItemAtPosition(int n): This method will remove the node at position n in the linked list. Assume that the first node of the linked list has a position number of 1 and the second node has a position number of 2 and so on.
This is my Code
AddItemToFront
public void AddItemtoFront(Item p)
{
Node newNode = new Node(p);
newNode.setLink(head);
head = newNode;
[Code] ....
I don't know what am I suppose to do inside the remove method
This is my first time using linked lists and for homework I have to make a program that allows the user to make a linked list of Strings (names) and then choose who to eliminate. For example,
Five people in a linked list of Strings: Joe, Mary, Sue, Tom, Hannah.
I would like the program to ask the user to choose a number between 1 and 5. If the user chooses number 2, Mary is the second person in the linked list so she gets eliminated.
The problem is that I'm not sure how to traverse through the linked list because they are of type String value, and I am looking for the name using the corresponding integer I mentioned above.
Here is my code:
package llchallenge;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;
import java.util.Scanner;
public class LLChallenge
{
List JosephusList = new LinkedList(); // order of names
[Code] ....
I have a Java Code:
POIterator mh_sh_highlight_all('java');
class that implements an Iterator.
A new instance of the Java Code:
POIterator mh_sh_highlight_all('java');
Class is supposed to traverse a binary tree in Post Order. But when I attempt to test a
Java Code: POIterator mh_sh_highlight_all('java');
Object in my main class, it doesn't work as its supposed to. I might be implementing it wrong.
Java Code:
public PostOrderIterator<E> implements Iterator<E>{
Deque<BNode<E>> somestack = new LinkedList<BNode<E>>();
BNode<E> position;
public POIterator(BNode<E>root){
somestack = new LinkedList<BNode<E>>();
somestack.push(root);}
[Code] ....
How get method of HashMap or Hashtable works internally in Java can any body let me know how does it work..
View Replies View RelatedI am having some problems with some code and I need an extra set of eyes. It appears I've missed something. I am getting a NullPointerException with a Hashtable object, which I can clearly see I've created. So I'm not quite sure why it is happening. I am pretty sure it is do with the code I've posted because I've tested everything else involved.Here is the code where it happens,
Java Code:
public void siteGen(String user, String site)
throws ExcGenDatabad, ExcSiteNodomain, Exception {
System.out.println("calling siteGen, user: " + user + ", site: " + site);
String nginx_template;
String fpm_template;
[code]....
I was browsing around and I found a question asking to find how many times a word occurred in a sentence. I am using a hashtable, over kill yes but I need to use them more. However my counter is not working, not really sure why.You can see in the main method I have two repeating names but it returns 0.
package frequency;
import java.util.Hashtable;
public class CheckFrequency {
hashtable<String, Word> words = new Hashtable<String, Word>();
[code]....
I am having some difficulty adding a new item to the HashTable when a collision occurs. We can only use the basic utilities to code this, so we are coding a HashTable by hand. We have an array of length of 10, which each index holds or will hold a Node for a Linked List.
The code hashes fine, adds the item, but the problem exists when adding items that already been hashed. The project is much bigger, but this is the engine behind the rest, and I figured I would tackle this first.
The items we are adding are objects which are states containing different information, we hash based on the ASCII sum % tableSize.
Here is the code I am testing with to add items:
HashTable ht = new HashTable(10);
State az = new State("Arizona","AZ","W",2,"Y",2);
State fl = new State("Florida", "FL", "F", 2, "X", 2);
State hi = new State("Hawaii", "HI", "H", 3, "Z", 1);
State al = new State("Alabama", "AL", "A", 5, "W", 0);
ht.insert(hi);
[Code] ....
I'm writing the remove method, where you insert the key and it searches the key, if the key is found you remove the value inside the table and return that value, if they key is not found you return null. I did this method but is not returning anything in the main so I try to print inside an if to see if it was entering the condition and it appears to be looping, I'm using arrays because its an assignment
public V remove(K k) {
int key = funcionHash(k);
V key2 = (V) tabla[key].value;
int intento=1;
if(this.estatus[key]==1){
while(intento<this.tabla.length/2){
if(this.tabla[key].key.equals(k)){
[Code] ....
I'm having a problem implementing double hashing when I insert a value into the table i get this for the output:
Insert []. Is there something I'm doing wrong? I'm not getting any errors
public static int size = 0;
public static ArrayList<Integer>[] a;
public static void interactiveMode(Scanner input) {
int menuChoice = 0;
do {
System.out.println("
Interactive Mode:");
[code]....
I need to implement a separate-chaining hash table from scratch and I don't need to know the code or anything I would just like an explanation of how I would go about doing the algorithm for this perhaps pseudocode and then I can figure out the rest.
View Replies View RelatedI'm having a problem with double hashing, its supposed to have the user insert an integer into the table and the integer is hashed into the table by the mod of the size of the table so say for instance table size 10 I insert 89 that inserts into 9 because 89%10=9 then i insert 18 that goes into 8 but then once i insert 69 its supposed to collide with index 9 and then uses 7-(69%7) for prime number double hashing...but it just goes into index 9 instead so in 9 it puts 89,69...there's no errors just the wrong output
System.out.print("Enter size of table: ");
int n = input.nextInt();
size=n;
a = new ArrayList[size];
for (int i = 0; i < size; i++) {
a[i] = new ArrayList<Integer>();
[code]....
How can I write a BufferredImage to an 8-bit .bmp using indexed colors stored in a <String,Color> Hashtable?
I've never used Hashtables before, and I didn't know color indexing existed until now, but I can do most other things in java fairly well.
I'm not looking for code, just the concept, as I really don't know how Hashtables work (although I could figure it out), and how color indexing does. I know how to write image files, just not indexed or with a specific number of bits. I am using Hashtables generated from GIMP.
EDIT: I mainly want to know how to save a BufferedImage as an indexed .bmp.
I have a data structure such as: ArrayList<ArrayList<Integer,String>
The data looks as [[1,2,3] [3,4] [99,98,40,32,45,65,1]]
I am trying to access each element and put them into a hashtable such as:
Hashtable<Integer,String>
With what I am doing below I am getting an out of bound error but can't see any other way of accessing the element
public static void hash(ArrayList<ArrayList<String>> list)
{
for(int i = 0; i < list.size(); i++)
{
int cnt = 0;
for(int y = 0; y < list.size(); y++)
{
if (! hashMap.containsValue(list.get(i).get(y)))
{
hashMap.put(cnt, list.get(i).get(y));
cnt++;
}
...
I have a jsp page that generate a hashtable and display its key-value pairs back to the browser. The problem is that it takes on an average about 15 minutes to build this hashtable, and as a result, I always get a timeout error. What can I do to avoid getting the timeout error without changing the server configuration for timeout
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