Dummy Node In Doubly Linked List - Cannot Find Symbol Variable Error
Jun 5, 2012
Im running into some problems with the Java compiler. This is my code:
public class DoublyLinkedList<T> implements SimpleList<T> {
protected Node dummy;
protected int n;
public DoublyLinkedList(){
dummy = new Node();
dummy.next = dummy;
dummy.pre = dummy;
n = 0;
[Code] ....
I want to use a dummy node in my implementation of the Doubly Linked List, so it will be easier to code all the methods I need to write. I keep on getting a problem with line 14 and 15:
dummy.next = dummy;
dummy.pre = dummy;
// cannot find symbol variable next (compiler error)
I am trying to create this program I am pretty sure it is easy but I am making it difficult lol, it keeps giving me a error, it is saying cannot find symbol - variable keyboard, I don't think I have keyboard as a variable but I may be wrong.
double distancel = keyboard.nextdouble(); that is the specific line ....
import javax.swing.JOptionPane; import java.io.File; import java.util.Scanner; //import java.util.totalInches; //instance variables public class Map{ public static void main(String[] args){
I'm having some trouble with figuring out how to move along a doubly linked list for an assignment. The program is supposed to be a simple board game simulation. Here is what I have so far:
Space.java:
public class Space { private String name; public Space next; public Space previous; public Space(String name) { this.name = name;
[Code]...
I seem to have been able to get all the other methods working properly, but I am pretty stuck on how to do the movePlayer. Specifically because it is passing an integer, but my objects are of type Space and Boardgame.
For the program I have to create, I need to be able to work with the elements of a circular doubly linked list to do the following:
Find an element in the list (specified as an argument) Insert an element after a specified element (specified as an argument) Delete an element (specified as an argument) Display the elements in the list
I can insert elements and display the elements, but I can't figure out how to search for an element, insert an element after a specified element, or delete an element.
What I am having trouble with is passing the elements in the list as arguments for searching, deleting, inserting after an element.
public class doublyLinkedList { private Node pointer; private Node dLL; private int count;
How can I insert a new item at the middle of a BookList . I have also got a Book class represting Book objects and a inner class BookNode referencing them.
public void add(Book newBook) { BookNode newNode = new BookNode(newBook); if (firstNode == null){ // no nodes in the list so add newNode at start firstNode = newNode; tempNode = newNode ; }
I have a couple more (2or3) and I believe I'll be ready to go 8-)This one is about an Army and a list of warriors... for example 1,2,3,4,5,6,7,9,10 .... and the user inputs points for two sequences, for example 1, 5 and 6,10 .... That means I have to take the array from the 1st element, up to the 5th one, and swap it with the elements from 6to10....
The nest list should be:
6 7 8 9 10 1 2 3 4 5
Things to keep in mind: The list will always have at least two warriors. The intervals will never interfere, and will at least contain ONE warrior..
It says: be careful when the intervals are next to each other, and when be careful when an interval starts with the first warrior, or finishes with the last warrior.
I cant figure out something in my code. I have to check whether given doubly linked list is palindrome or not. If it is palindrome it should print 1 , if not -1. My code has no errors but it always prints -1. I tried debugging but first comparisongives always false and function cant reach to else statement.
Are there any logical errors or i cant do right way of comparison?
import java.util.Scanner; class DLLNode<E> { protected E element; protected DLLNode<E> pred, succ; public DLLNode(E elem, DLLNode<E> pred, DLLNode<E> succ) { this.element = elem; this.pred = pred; this.succ = succ;
I am trying to create doubly linked list that can hold huge numbers (i.e. 123456789) and add them together. I have seen some examples on how to do this for linked list, but none really for doubly linked list.
Here is my test driver:
public class HugeNumberDriver { /** * Main method with some test code */ public static void main(String[] args) { // Create a HugeNumber that is 123456789 HugeNumber h1 = new HugeNumber(); for (int i=9; i>=1; i--)
[Code] ....
Output:
h1 is 987654321 h2 is 88888888885555555555 Exception in thread "main" java.lang.NullPointerException at HugeNumber.<init>(HugeNumber.java:52) at HugeNumberDriver.main(HugeNumberDriver.java:29)
As you can see the numbers are displayed incorrectly and the rest of the program does not run. I have a feeling that it has to do with my deep copy constructor or my addDigit() method
I am trying to advance to the next node in my linkedList. Below is what i have so far.
/** * Move forward, so that the current element is now the next element in this sequence. * @param - none * @precondition: * isCurrent() returns true. * @postcondition: * If the current element was already the end element of this sequence (with nothing after it), then there is no longer any current element. * Otherwise, the new element is the element immediately after the original current element. * @exception IllegalStateException * Indicates that there is no current element, so advance may not be called. **/
I have a custom linkedList(single) class that uses the provided node class. Now I have another class to QuickSort this.(left out for brevity, i just wanna focus on editing the L.head). However, instead of passing the quicksort method the entire linkedList, I want to pass it just the head from the linkedlist.
My problem is accessing this head node and changing it from the quckSort method/class, and I dont want to delete it or simply just change the element value
Main:
public class TestLinkedList { public static <E extends Comparable<E>> void main(String[] args) { MyLinkedList<Integer> L = new MyLinkedList<Integer>(); L.add(3); L.add(1); L.add(2); System.out.println("Initial=" + L); MySort.quickSort(L.head); System.out.println("After ="+L); } }
QuickSort:
public class MySort { public static <E extends Comparable<E>> void quickSort(MyNode<E> list) { list = list.next; }
Node Class:
public class MyNode<E extends Comparable<E>> { E element; MyNode<E> next; public MyNode(E item) { element = item; next = null;
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
The only problem I have now is getting a method to return the median element of a LinkedList without using loops of any kind or by using a global counter anywhere.
I've pretty easily figured out how to get the index value for the median number (there is some lee way allowed. If the list has an even size, any of the middle values are accepted) but I can't figure out how to print it without loops.
I'm sure I need to make a method that finds an element at the given index value, but I don't know how to do it without loops.
Here's all of my code. Inside is my Assignment3 class I use for testing, StudentList which contains the LinkedList head and other List methods, and StudentNode which is obviously, the Node class. Also I've attached the first test1.txt file as well.
import java.io.FileNotFoundException; import java.util.*; public class Assignment3 { public static void main (String []args){ StudentList<StudentNode> myList = new StudentList<StudentNode>();
[Code] .....
I tried making a method that basically counts up the list recursively then a second method that counts down recursively and is supposed to stop once it hits the middle number, then print that node.
Basically I am supposed to build a symbol table for storing identifiers (an array) and then link the number line that identifier is stored on. I set the array to null and if the identifier is found then I link in a line number node. If it isn't found then I add a new identifier and line number.
My problem is that we are supposed prompt for the line number and identifier in the main class, but I don't know how to "connect" the classes per say so I can do the add method in the SymbolTable class.
import java.util.*; public class Assignment { public static void main(String[] args) { Scanner console = new Scanner(System.in); SymbolTable table = new SymbolTable(); boolean quit = false;
The problem I'm having right now is invoking the get method in my main. I get a "cannot find symbol - variable deposit" error message. I also am at a loss as to what to do for the first two classes as well as the interest class. What I had for the first two didn't work, so I scrapped itand don't remember what it was.
Here's the code and error message:
import java.text.NumberFormat; import java.util.Scanner; public class BankAccount { private double balance; private double name; private int BankAccount;
I have written the below program and while compiling i am getting error. The program and error details goes as follows,
//compute distance of light travels using Java long variable. class Light { public static void main(String args[]) { int lightspeed; long days; long seconds; long distance;
[code]....
I have given the Java file name as 'Light.java'. I have also verified the availability of the java file and compilation path. both are matching. Also, Java file name and class name defined are also same.
I keep getting errors, cannot find symbol. Not sure where I am going wrong.
java:139: error: non-static method integerPrompt(String,int,int) cannot be referenced from a static context int regNumber = integerPrompt("Enter registration number", 100, 5000); ^ Program7.java:145: error: cannot find symbol theSubject = integerPrompt(SubjectsPrompt, 1, SubjectQty); ^ symbol: variable theSubject location: class Program7
Java Code:
import java.util.*; import java.io.*; import java.util.Scanner; public class Program7{ public static void main(String args[]){ Student student = new Student();
I thought I have been getting this right, but I keep getting stuck on this one error. Here is my code. Why it keeps getting a 'cant find symbol' error?
// import statements import java.util.Scanner; // class declaration public class GradeConverter { // main method declaration public static void main(String[] args) { // display a welcome message
[code]....
It is just a simple input a number between 1-100 and it spits out the letter grade.
I'm picking up Java for a class, and having prior C++ knowledge this stuff has been fairly straightforward with the exception of trying to learn the whole IO system in this language.
className.java:line_number: error: cannot find symbol myList.add(input); ^
I have dealing with this error left and right after picking up this language, and I can never seem to figure out what it's trying to tell me. I've heard people say it's referring misspelled objects or methods, but I've double and triple checked my code and that never seems to be true for me.I'm trying to make a small program which will allow me to play with the LinkedList object so I can gain some familiarity with how they work in Java, and I have this code so far:
import java.io.*; import java.util.*; public class playWithLists { public static void main(String[] args) throws Exception { //List<String> myList = new LinkedList<String>(); LinkedList myList = new LinkedList(); BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String input = "";
[code]....
The compiler is giving me an error at line 16 (specifically: myList.add(input); )
programming altogether and after almost reaching half way in the 'Head first java' book I decided to try and apply some of what I've learnt so far and write my first 'Object orientated' program. As this is pretty much the first program I've ever written, I decided to write a program to ask for two integers and add them both together and then present them to the user (the goal eventually being a basic fully working command line calculator with +,-,* and /. I'm expecting many compile errors but not the following errors below.
I have three .java files contained within a folder and after trying to figure out how to compile all three files (as they use one another) all at once, I came across this ---> javac *.java
so I typed this in the command line whilst in the directory containing the three files assuming *.java is the best approach and then I receive the following errors:
inputOutput.java:10: error: cannot find symb c.addition() = intIn.nextInteger(); ^ symbol: variable c location: class inputOutput
import java.util.*; public class CQ1v1{ public static void main(String args []) { Scanner in = new Scanner (System.in) ; String name = ""; System.out.println("Welcome to the Interrogator") ;
[Code] ....
When I compile getting
CQ1v1.java:12: error: cannot find symbol x = in.nextLine (); ^ symbol: variable x location: class CQ1v1 CQ1v1.java:21: error: cannot find symbol
I am working on a StringBuffer program and I am getting the following error message: Cannot find symbol - method append(java.lang.String) with this part of the code selected:
