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] ....
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 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]....
What are the difference between hashmap, linkedlist and arraylist ... when they are used and why?
View Replies View RelatedI 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 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 working on a text based adventure game. (This is NOT OOP at all) The problem comes in at my second if statement inside my loop, it is not adding 1 to my array locations[] it keep printing location[0] then a 1 at the end. Not really sure what is going on here. I would like it to when I type "Go north" it adds 1 to locations[]
E.G
locations[0]
Go north
locations[1]
go north
locations[2]
package com.PenguinGaming;
import java.util.Scanner;
public class Game{
[code]....
I'm really struggling adding JLabels to my GUI. The code is giving no errors but the JLables aren't showing up as I think I've done something else wrong. Here's my method for adding the JLabels:
public void showGraphics(){
for(int i=0; i<message.length(); i++){
if(message.charAt(i) == '#'){
JLabel localLabel = new JLabel("test label");
getContentPane().add(localLabel);
}
}
}
I think the problem might be to do with how the rest of the GUI is setup and the fact that I haven't specified where to add the JLabel just that I'm adding them.
Here's what my GUI looks like.
I want the JLabels above the JTextArea.
Code of file:
Java Code: import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
[code]...
The serializable class ImagePanel does not declare a static final serialVersionUID field of type long public class ImagePanel extends JPanel{ ^^^^^^^ ^ ^^2 problems (1 error, 1 warning) mh_sh_highlight_all('java');
im basically just trying to put the image inside the GUI and centre the text underneath it. Which is hard to believe since the text is above the image in the code .
I'm trying to make a simple program that will show the amount of a bill, the tip, tax and total with all 3 added.
Right now i am having issues with line 12. I am getting the error "Variable amount might not have been initialized
I thought i did initialized it.
import javax.swing.JOptionPane;
public class BillAmt {
public static void main(String[] arg) {
String amt;
double tax, taxTotal, tip, total;
tax = 6.75;
double amount;
taxTotal = amount + tax;
tip = taxTotal *.15;
total = tip + taxTotal;
amt = JOptionPane.showInputDialog("Please enter the amount: ");
amount = Double.parseDouble(amt);
package calculator;
public class operations {
int a = 5;
int b = 10;
public void add(int a,int b)
{
int c = a+b;
System.out.println(c);
}
}
I am not getting output to this question though it runs.
I have a supermarket checkout line where i have a list of available products on the left and then a basket on the right with the products in. The products are listed in an array, here is the product class
public class Product {
private String name;
private double weight;
private double price;
[Code] ....
with getters and setters excluded, and the list these are put into
public class productList extends DefaultListModel {
public productList (){
super();
}
public void addProduct (String name, double weight, double price, int code){
super.addElement(new Product(name, weight, price, code));
i have the price for each product to be displayed in a text field with the following code
addBasketItem = new JButton();
getContentPane().add(addBasketItem);
addBasketItem.setText("Add >");
[Code] ....
defaultCheckoutList contains my available items and defaultMainList is the basket, with mainTillPrice being the jtextfield.
This works to get the price however it just replaces each time i make a new entry with the price for the next item, i want a total of the price of all the items i have added, but not sure how.
how can I add the numbers in quantity where it will automatically put in total?
im using netbeans.
just want the codes for how to add the listed quantity?
I want to add validation to some of the elements in my constructor.
Person(String idIn, String nameIn, ) {
this.id = idIn;
this.name = nameIn;
}
I want to be able to check that the data for the ID is limited to a certain collection of characters formatted in a certain. For example, I may wish to limit it to 5 lowercase letters or numbers, or a combination of both. How could I do this?
Here is my program. I have to add the outputs from variable 'done' together. It seems to not work inside or outside the loop.
//A program that will find the last/check digit of a Book ISBN number.
import java.util.*;
public class ISBN {
public static void main(String[] args) {
Scanner kb = new Scanner(System.in);
System.out.println("Enter the ISBN number>");
String isbn = kb.nextLine(); //Even though the ISBN code is a number,
[Code] .....
How do i add a ratio into this program. it needs to find the ratio from lowercase to uppercase.
import java.util.Scanner;
public class Strings
{
public static void main(String[] args)
[Code]....
I wanted to create a interface with buttons ofshapes and type of transformation where user first select a shape, the shape will appear and user will have to click on the buttons on resize, reflect, rotate or skew to transform to shape. How can i do the coding? such as adding listeners to the shapes?
View Replies View RelatedI am doing a few Spring tutorials and in eclipse and for each tutorial I have to right click my project, build path, and then add external archives and then select the spring JAR files I want to bring in and use before my project will successfully compile and run. I was just wondering is this required for every project or is there a way I can set eclipse up to look in these locations for every project without me having to explicitly tell it too?
View Replies View RelatedI have been trying my hand at making 2d top down view games and have found myself repeatedly using the same code so i created a file with all the functions so when it is down i just import the jar and dont have to keep rewriting functions. I have trouble because the background is loaded on the screen and i dont know why as i didn't tell it to load. In fact I set the panels visiblity to false. Both of my classes are in the same package. Why I still get the Image.
Walking Turtle
Java Code: import javax.swing.*;
import java.awt.event.*;
public class turtleWalker extends JFrame{
public static void main(String[] args){
JFrame frame = new JFrame("Walking Turtle");
[code]....
I am trying to add two bytes together in binary. The problem is that I need to print the carryover also. The printed result should be 8-bits long if the byte or the integer converted in binary is less than 8-bits the empty space should be filled with 0-s. I figured out how to print and add them, the part with the filling the blank with 0-s too. how to print the carryover. For example:
byte x =15;
byte y =9;
the output will be :
00011110 - carryover
x 00001111
y + 00001001
__________________
00011000 - result
import java.util.Scanner;
public class Addbytes
{
public static void main(String args [])
[code]....
I am new to swing and I wanted to know how to be able to make a second row of buttons. Right now I have a text pane at the top and at the bottom one row of buttons. But I need to add another row or two of buttons. I've only been coding in Java.
public class TextPane {
public static void main(String[] args) throws IOException
{
/////////////
//I/O FILES//
/////////////
//Create the input file
FileWriter inputFile = new FileWriter("userInputStory.txt");//story user creates with the <nouns>, <verbs>, etc
PrintWriter inputFileWriter = new PrintWriter(inputFile);
[Code] .....
So I'm doing a basic MVC layout for a pretty basic game that I am making in order to understand the whole MVC layout. The game requires the user to move up/down/left/right via JButtons on the GUI. Since I'm using an MVC layout and my buttons are in a different class than the ActionListeners, I was wondering what the best way to add the action listeners are?
Method 1:
View Class ActionListener method:
Java Code: public void addMovementListeners(ActionListener u, ActionListener d, ActionListener l, ActionListener r){
moveUp.addActionListener(u);
moveDown.addActionListener(d);
moveLeft.addActionListener(l);
moveRight.addActionListener(r);
[Code] ....
Which method is better? Is there another method that is even better than these two? Trying to get this MVC thing down.