I have a LinkedList class that implements a game.
I want to create a list and populate it when a LinkedList object is created .
.
The game constructor takes a word.
How do you populate a LinkedList of any type for example suppose I have a LinkedList of the Integer type, How do I fill it up with 10 integers?
I have a Queue class (containing a LinkedList plus a few other variables and stats for my project), which works fine with the standard LinkedList, but I'm trying to add my own code for MyLinkedList.
However, I keep getting a NullPointerException at my remove method.
public class MyLinkedList<T> {
Node head;
public MyLinkedList() {
head = null;
}
public class Node {
T contents;
Node nextNode;
[Code] ......
I must convert some Java fubction to a plain "Basic", as VB6. The problem I'm facing is this: Suppose I have an array like
Java Code:
private static final int[][] Terms = {
{193, 26, 13},
{183, 29, 14},
{170, 20, 11}
}; // total 659 terms mh_sh_highlight_all('java');
How do I populate the Terms array?
Is it:
Terms[0,0]=193;
Terms[1,0]=26;
Terms[2,0]=13;
Terms[0,1]=183;
Terms[1,1]=29;
Terms[2,1]=14;
Terms[0,2]=170;
Terms[1,2]=20;
Terms[2,2]=11;
?
I'm not sure this is right... Is there a way to automate this process? What if we have arrays like int[][][] Terms? This is terrible... Is there a software tool for this?
I have just begin to understand collections in Java. I read about the differences between LinkedList and ArrayList but have several doubts on it. I have mentioned them below
1) Why retrieving in ArrayList is faster then LinkedList?. Since both have the get method how does performance differ?.
2) How does re-sizing happens internally in ArrayList when a item is added or removed?. How slow this is compared to the pointer re-shuffling in LinkedList when a item is added or removed?.
What is the starting index for linked list, 0 or 1. I know an array starts at 0 so wouldn't a linked list?
View Replies View RelatedMy remove(item E) method is working fine if I remove an item that is in the list. However, it has an error when I try to remove an item which is not on the list!
Linked List Class
import java.util.NoSuchElementException;
public class LinkedList<E>
{
private Node<E> head; // head node of the list
private int size = 0; // number of elements that have been added to the list
// Returns the element at a specific list index.
// Big-O: O(n) (due to the nodeAt call, which must traverse the list)
public E get(int index)
[code]...
I'm doing LinkedList at the moment and I'm having a bit of trouble with my assignment. The part I'm struggling with is remove an employee from a training course (as specified by their employee number),
what I'm confused about is iterating through the linked list to find the employee we're looking for. What I would do in this situation if I was using an array list is
for(Employee emp : myList) {
if(emp.getEmployeeNumber().equals(searchedNumber)) {
remove from training course..
break;
}
}
"Can only iterate over an array or an instance of java.lang.Iterable" is what it is telling me, and I can't figure out why/how its done differently for linked lists.
Okay, I'm having a problem with my LinkedList. When I run the driver program it's telling me that I have no "add" method and I don't know what's going on.
Driver Program:
public class TestLinkedList {
public static void main(String[] args)
{
MyLinkedList<String> L = new MyLinkedList<String>();
L.add("Browns");
L.add("Ravens");
L.add("Steelers");
[code]....
I can't figured out why it's keep giving me error when I tried to add i to the linkedlist. I tried changing it to other numbers but keep giving me nullExceptionPointer.
public static void subset(double[] weight, double[] value, int start) {
double sumWeights = 0;
for(int i = start; i<weight.length; i++){
if(sumWeights+weight[i]>L){
continue;
[Code] ....
What are the difference between hashmap, linkedlist and arraylist ... when they are used and why?
View Replies View RelatedThis is the method public void populateMatrices(int [][]mat1, int [][]mat2). I know how to do it for one matrix, but what do we do for the additional matrix? Here is the code I have so far.
for (int row =0; row<mat1.length;row++){
for (int column = 0; column<mat1[row].length;column++){
mat1[row][column]=1 + (int)(Math.random()*5);
I have a method that accepts JSONArray as parameter and returns the values of it as ArrayList Object. My question which of these ways is appropriate in populating the ArrayList object this method populates the arraylist upon creation of object (I don't know what the right term to use, but as netbeans IDE suggest, JSONArray object should be final since it was used in inner class.).
private List<String> getStringList(final JSONArray jsonArr) {
return new ArrayList<String>() {
{
try {
for (int i = 0; i < jsonArr.length(); i++) {
add(jsonArr.getString(i));
}
} catch (JSONException ex) {
ex.printStackTrace();
}
}
};
}
this second method is the usual way of populating collection
private List<String> getStringList(JSONArray jsonArr) {
List<String> strList = new ArrayList<String>();
try {
for (int i = 0; i < jsonArr.length(); i++) {
strList.add(jsonArr.getString(i));
}
} catch (JSONException ex) {
ex.printStackTrace();
}
}
What are the advantages and disadvantages between the two? like which is faster? or which consumed larger memory?
I am trying to populate a Jlist for information stored on a database. The database contains football club names, but instead of being populated with their names it just has a hexadecimal reference ( Club@183357c4 ) for each club object.
View Replies View RelatedI have been given a task to do, which is to create a memberList and populate it with data. The constructor has been created with me, but I am required to add code to display the memberList. I am also required to creates a method to display members.This is the method I created:
/**
* Populates the list of members.
* Displays the membership numbers and names of library members in ascending membership number order.
* The first member is selected by default.
*/
public void displayMembers()
{
initComponents();
library = new LibraryCoord();
Collection<Member> Member = library.getMembers();
memberList.setListData(Member);
memberList.setSelectedIndex(0);
[code]....
The code below TO DO is mine.What is meant to happen when I run the project is for a GUI form list to show the members of memberList. However, it does not.
I am having a hard time trying to wrap my head around trying to get a couple of columns in a datatable populated with values from a @OneToMany collection. The concept is simple but my brain refuses to grasp it!! I will try to make this brief...
I have several forms built with primefaces 3.5 using NetBeans 8 IDE on a JBoss EAP 6.21 server, and JPA 2.1 annotations. Data is extracted from an Oracle 11 database, which consists of several lookup tables, as well as a primary table and secondary table. Using the EntityManager createQuery method I query the database, which of course returns a resultset. The query grabs all records from the primary, as well as values from 2 specific columns of the secondary database, based on search criteria entered by the user on a primefaces search form. The returned results are then iterated through, this is where I am trying to get the values from the secondary table to populate specific fields in the datatable.Here is the applicable code from the list.xhtml form containing the datatable:
<p:dataTable id="datalist" value="#{foreignPartyController.returnedSearchResults}" var="item"
selectionMode="single" selection="#{foreignPartyController.selected}"
paginator="true"
rowKey="#{item.foreignPartyId}"
rows="30"
rowsPerPageTemplate="10,20,30,40,50"
sortOrder="ascending"
resizableColumns="true"
style="overflow: auto"
[code]....
As odd as the code may look (and I will completely understand anyone cringing as to some of the coding methods I use), specifically with the ui:repeat tags nested inside the datatable tag of the list.xhtml form, I strangely do see the values from the secondary table showing up in the form showing the results in a datatable. However, when the user clicks on a specific record in the returned resultset listed in the datatable, another form is opened and populated with the values from the datatable, but the 2 fields on that form that should be populated with the 2 values I referred to before from the secondary table (i.e. policy1Num and totalPayoutAmt) do not have the values in them.
This is partly because I have those 2 fields in the editable form pointing to the managed bean of the secondary table (code from that bean not shown here), rather than the same "polNum. policy1 Num" and "totPayout.totalPayoutAmt" var I am using in the list.xhtml form. How those values are being successfully returned into the datatable of the list.xhtml form - I happened to "stumble" across the use of the "polNum" and "totPayout" vars with the "policy Payment Collection" list. I do not know how to do the same thing for those 2 fields in the editable form.how a datatable gets populated, specifically with values in a @OneToMany collection,
I am getting "Type safety: Unchecked cast from Object to LinkedList<EventData>" in eclipse for a piece of code stated below
public LinkedList<EventData> loadFromFile(File file) {
queue=new LinkedList<EventData>();
//Some piece of code
return (LinkedList<EventData>)queue.clone(); //--->getting warning here
}
I know that because clone() method is returning Object, hence compiler doesn't have type information that's why showing warning. I don't want to suppress this warning instead i want to fix it.
I am parsing an XML file. i.e.
<people>
<person firstname="John" lastname="Doe" age="50" />
<person firstname="Thomas" lastname="Jefferson" age="260" />
<people>
I have created Person.java with the following attributes:
private String firstName;
private String lastName;
private int age;
My main method parses the XML, loops through each person, and gets the attributes for each.
I need to create instances of my Person class. I could write something like this:
Person person = new Person();
for (int i = 0; i < attributes.getLength; i++) {
if (attribute.getName(i) = "firstname") { person.firstName = attribute.getValue(i);}
if (attribute.getName(i) = "lastname") { person.lastName = attribute.getValue(i); }
if (attribute.getName(i) = "age") { person.age = attribute.getValue(i); }
}
Since my actual XML has quite a few attributes, I would rather do something like this:
Person person = new Person();
for (int i = 0; i < attributes.getLength(); i++) {
person[attribute.getName(i)] = attribute.getValue(i);
}
This doesn't work.
Java Code:
import java.io.*;
import java.util.Scanner;
public class asciiFile {
int height;
int width;
Scanner input;
char[][] poop;
public asciiFile(File f) throws FileNotFoundException{ //constructor
[code]...
The constructor is supposed to take an ASCII file, take the numbers in the file, and populate a 2D array with the numbers in the file.
For some reason, the for loop I use to populate the array works outside of the constructor. When I put it in one of the methods, it runs normally. However, when I keep it in the constructor, I get the following error:
Exception in thread "main" java.lang.NullPointerException
at asciiFile.<init>(asciiFile.java:16)
at main.main(main.java:6)
My code runs and populates an arraylist. However my break statement, while stopping the loop ends up being added to the arraylist. And I'm not sure how to fix this error.
public static void main(String args[]) throws Exception
{
// declaring variables
String input = "";
// creating array list
ArrayList<String> nameList = new ArrayList<String>();
[Code] ....
We are getting "Code too large" compilation error for one of our class. This class contains public String fields for label ID and value. We use this class for localization, except for English all other language labels come from .properties files.
The reason we are getting this error is because we have a static block in which using reflection we are populating a HashMap with all public fields and their value. The number of fields have gone up to the extinct where we are crossing the 64K limit for a static method. One of the most feasible solution was to use .properties files for English labels as well.
I will be calling this class MyLabels. We defined a super class for MyLabels called MyLabelsExt. And now we are adding labels into the super class instead of the MyLabels. By running some tests we confirmed that the map that we initialize in MyLables class contains all the fields from both MyLabels and MyLabelsExt class.
How is the 64K limit error not coming if the labels are defined in a super class. Does that mean Java is able to identify that some of the fields are coming from parent class, and that is being treated as separate from the child class. And how is the map that we initialize having all the value.
I have stumbled onto a problem with ArrayLists (not sure if nested ArrayList objects would be a more accurate description) ....
As simply put as I can describe it, I have an Inventory class which creates an ArrayList of a Product superclass, which has two subclasses, PerishableProduct and ItemisedProduct.
By default, the program is meant to have a starting inventory, which is why I have added them in the constructor
public class Inventory {
private List<Product> products;
public Inventory() {
addProduct(new Product("Frying pan", 15, 20));
addProduct(new PerishableProduct("Apple", 5.8, 30, 7));
addProduct(new ItemisedProduct("Cereal", 5.8, 0));
// this is where I am having problems. Wanting to add
// objects to the ItemisedProduct's ArrayList for cereal.
}
Within the ItemisedProduct subclass is yet another ArrayList which is meant to hold serial numbers.
public class ItemisedProduct extends Product {
private ArrayList<String> serialNumbers = new ArrayList();
public ItemisedProduct(String name, double price, int qty) {
super(name, price, qty)
[Code] .....
My problem is that I do not know how to populate the serialNumbers ArrayList from the Inventory class' constructor. Because technically, quantity is defined by how many serial numbers are created.
I have tried running the java application without adding the site to site list in java security tab. But I get a sand box message as APPLICATION BLOCKED BY SECURITY SETTINGS. How to run the java application without adding the site to site list in java security tab.
View Replies View RelatedI want to develop a Java program that uses OpenScript APIs to test my applications. The OpenScript framework automatically creates the Java Code so I was thinking of either using this code or create my own using the APIs.
I tried both options using NetBeans but I'm getting errors everywhere starting with the library import. I'm pretty new to Java so I'm sure I'm missing a lot of things here. I pasted the code below from the OpenScript framework that want to use in a stand-alone file for your reference.,
import oracle.oats.scripting.modules.basic.api.*;
import oracle.oats.scripting.modules.browser.api.*;
import oracle.oats.scripting.modules.functionalTest.api.*;
import oracle.oats.scripting.modules.utilities.api.*;
import oracle.oats.scripting.modules.utilities.api.sql.*;
[Code] ....
I've written a java application with several classes all in the same .java file. It works just fine. Now, I've broken it up so that each class has its own .java file. Still works fine. My next step is to put those classes into a package, but I'm not about to get the program to run.The .java source files are all in /home/user/src
I've set the CLASSPATH to /home/user/src..All of the source files have "package com.myfirm.program" on the first line.I compiled the application with:
javac -d . File1.java File2.java File3.java (etc...)
the compiler created the directory: /home/user/src/com/myfirm/program and put all of the .class files in there.So how do I get the program to run? if I run from /home/usr/src
java File1
I get: Exception in thread "main" java.lang.NoClassDefFoundError: File1 (wrong name: com/myfirm/program/Program)
I create 2 files:
CircleCalculationMethod.javaMain.java
In Main.java, How can i call method in CircleCalculationMethod.java ?
Should I put everything in same folder ??Should i do something like "import CircleCalculationMethod.java"Should i do something like create a package ...
I use Eclipse software
The title of Question might seem old and previously asked.But I have a Question that what is difference between javaSE and Java EE.Although I knew what comes under JavaSE and What is under JavaEE.But My question is that.
What happens when we add PATH in our Environment Variable How does Eclipse or Other IDE use it?
Second Question is.
For Java SE we declare a Path Variable but for Java EE we do not add any library?(I know we add some jar file like for Servlet(Servlet-api.jar) and for EJB(Ejb.jar),But What is actaul difference?