Searching For Object In Linked List Then Removing The Object
Nov 19, 2014
I have just started working with linked lists. I have a linked list of Objects and I want to be able to search for a specific object. But currently my code continues to return false. Also how would I go about removing the first index of the linked list.
public static void main(String[] args) {
LinkedList<Cookies> ml = new LinkedList<>();
int choice = 0;
while (choice >= 0) {
choice = menu();
I have some class called sorted to sort the linked list through the nodes of the list. and other class to test this ability, i made object of the sort class called "list1" and insert the values to the linked list.
If i make other object called "list2" and want to merge those two lists by using method merge in sort class. And wrote code of
list1.merge(list2);
How can the merge method in sort class know the values of list1 that called it as this object is created in other class.
I am trying to put a reference to a given subclass object into a linked list, and then come back later, and invoke a method of the subclass object that is in a given spot in the linked list. This produces an error because Object does not have that method. Is it necessary to cast the object to the correct subclass every time I want to use one of its methods, or is there a way to convince the JVM to treat it as always of type MySubclass?
Ok here I have a code that generates 1 million random values then converts them to a string then hashcode. I then insert into a linked list and then I want to run through each hash and find it in the linked list timing each run then averaging out the time at the end.
It works great for smaller amounts of numbers it is searching for (fine under 50 thousand searches for the for loop starting at line 24 LinkedListTest.java) but when I try to do the full million searches it gives me "a Exception in thread "main" java.lang.StackOverflowError" at line 158 in List.java. Maybe im getting tired but I cannot figure out why.
// class to represent one node in a list class ListNode< T > { // package access members; List can access these directly T data; // data for this node ListNode< T > nextNode; // reference to the next node in the list
with arrays its binary search which finds a value in O(Logn) time but what about linked lists ? the most effiecient algorithm will be O(n) ? and i know that binary search cannot be implement on a linked list , therefore , the only way to search a linked list is a linear search ?
I am new to Java and have read books, the Java docs, and searched the Internet for my problem to no avail. I have an Array of objects that contains strings. How can I get the object's strings to print in a list so that the user can select that object to manipulate its attributes? For example, the user can select "Guitar 1" from a list and manipulate its attributes like tuning it, playing it, etc. I have a class called Instruments and created 10 guitar objects.Here is the code:
Instrument [] guitar = new Instrument[10]; for (int i = 0; i < 10; i++) { guitar[0] = new Instrument("Guitar 1"); guitar[1] = new Instrument("Guitar 2"); guitar[2] = new Instrument("Guitar 3"); guitar[3] = new Instrument("Guitar 4"); guitar[4] = new Instrument("Guitar 5"); guitar[5] = new Instrument("Guitar 6");
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.
I'm almost finished my Bank Account exercise and I found myself stuck at the last part. Its asking me to add a method that asks the user to input the name of the account into which they want to deposit money, then search the ArrayList for that account. If it is found, the user is asked how much money they wish to deposit.
I already have my deposit method sorted so basically what I need is just searching through the ArrayList by the name variable. I assume its don't by iterating through with some form of for loop.Heres what I have:
import java.util.Scanner; public class BankAccount { private double balance; private String name; public BankAccount(double balance, String name){ this.balance = balance;
[Code]......
And the driver class
import java.util.ArrayList; import java.util.Scanner; public class BankDriver { Scanner scan = new Scanner(System.in); ArrayList<BankAccount> list; public BankDriver(){
I'm trying to use LinkedBinarySearchTree but a lot of the variables are protected in BinaryTreeNode. I am creating a BinaryTreeNode object but it still isn't allowing me to use them. The variables I am trying to use are element, left, and right.
import ch11.exceptions.*; import ch10.LinkedBinaryTree; import ch10.BinaryTreeNode; /** * LinkedBinarySearchTree implements the BinarySearchTreeADT interface with links.
*/ public class LinkedBinarySearchTree<T> extends LinkedBinaryTree<T> implements BinarySearchTreeADT<T>
Create an equals method that takes an object reference and returns true if the given object equals this object.
Hint: You'll need 'instanceof' and cast to a (Geocache)
So far I have:
public boolean equals(Object O){ if(O instanceof Geocache){ Geocache j=(Geocache) O; if (this.equals(j)) //I know this is wrong... but I can't figure it out return true; }
else return false; }
I think I have it correct up to the casting but I don't understand what I'm suppose to do with the this.equals(). Also I'm getting an error that I'm not returning a boolean... I get this all the time in other problems. I don't get why since I have to instances of returning booleans in this. "returns true if the given object equals this object" makes no sense to me. I assume the given object, in my case, is 'O'. What is 'this' object referring to?
Suppose that you have an ArrayList and that it contains String objects. Which declaration of the ArrayList requires that objects retrieved using the get method be cast to Strings before calling a String method?
I. ArrayList a = new ArrayList(); II. ArrayList<Object> a = new ArrayList<Object>; III. ArrayList<String> a = new ArrayList<String>;
A. I only B. II only C. III only D. I and II only E. I, II, and III
I know that all of these are ways to declare an Array List, but I am unfamiliar with the last two since I usually just declare my Array Lists with the first option.
lst contains list of objects and one of the objects contains the property bDate(Timestamp) which has the value 28-2-1989 00:00:00.0, now I just wants to change the value into 28-2-1989 and store it back into the List as a Timestamp. how can I do that.
I am following those three tutorials and I have completed it with success.
( [URL] .... ) ( [URL] .... ) ( [URL] .... )
But then, as author haven't implemented removeCountries method I tried to create it. What I did initially was to just add to class Countries this method:
public boolean removeCountry(Country country) { return countries.remove(country); }
But although compiler wasn't complaining it didn't work. Actually it worked last night (before reboot) but not today. Must be some SOAP iterator/binding thing or whatever. Or I thought that it worked but in fact it didn't.
Here are original classes:
//------------------------------- public class Country { String CountryId; String CountryName; public Country() { super();
[Code] ....
I would like to avoid my own iterator as JDeveloper can generate automatically iterators for webservices, but if I can't get it that way, what would be better way to write above mentioned iterator in removeCountry method?
Is there any way to remove object directly with something like this:
co.countries.remove(o); co.removeCountry(country)
using method
// This left unused public boolean removeCountry(Country country) { return countries.remove(country); }
I want to create a program where I need to create an object of list type such as text file will contain nos like 1,2,3,4,5 and write into text file and delete the in FIFO order i.e 1,2,3,4,5...how i can achieve to write a program? I tried bt everytime got concurrent modification exception or Array out of bound exception.
How to use the id parameter in my documents entity to download documents from a list of documents. Normally I use ListDataModel and the getRowData method. I would like to know how to achieve the same thing using an ordinary List object.
My list of documents is called List<CountryDocs> selectedDocs;
Clicking on the download link calls the following method in my managed bean:
@ManagedBean(name = "countryDocBean") @SessionScoped public class CountryDocBean { private List<CountryDocs> selectedDocs; public StreamedContent getDownloadedFile() {
[Code] ....
Debugging shows the value for the id is 0 and this results in a NullPointerException. I've tried several methods for grabbing the document id in my backing bean, but no luck yet. I also read about the the ViewParams and ViewAction method but they caused validation errors to do with the <f:metadata> tags. I don't know how to obtain this value using a normal List object.
Now lets say that I want to access a method 'addInterest()' that is in the 'SavingsAccount' class I would have to do: '((SavingsAccount)s).addInterest();'
The question I have is why do I have to cast 'b' to SavingsAccount? Isn't the actual object reference of 'b' already an instance of 'SavingsAccount' class? How does the 'BankAccount' affect the object itself? I'm really confused as to what class is truly getting instantiated and how BankAccount and SavingsAccount are both functioning to make the object 'b'.
I don't understand why the object reference variable 'a' cannot be recast from a thisA object reference to a thisB object reference.Is it the case that once a reference variable is linked to a particular object type then it cannot switch object types later on.I am facing the Java Associate Developer exam soon and I am just clearing up some issues in my head around object reference variable assignment,
class thisA {} class thisB extends thisA { String testString = "test";} public class CastQuestion2 { public static void main(String[] args) { thisA a = new thisA(); thisB b = new thisB();
I am trying to get this to where I can type in a name and it will search through each object and print back the corresponding object info.
Java Code:
import java.util.Scanner; public class MyPeople { public static void main(String[] args) { Person[] p = new Person[] { new Person("Chris", 26, "Male", "NJ", "Single"), new Person("JoAnna", 23, "Female", "NJ", "Single"), new Person("Dana", 24, "Female", "NJ", "Single"), new Person("Dan", 25, "Male", "NJ", "Single"), new Person("Mike", 31, "Male", "NJ", "Married") };
Task:The main method of the class Things below creates an object called printer deriving from the class PrintingClass and uses that object to print text. Your task is to write the PrintingClass class.
Program to complete: import java.util.Scanner; public class Things { public static void main(String args[]) { String characterString; Scanner reader = new Scanner(System.in); PrintingClass printer = new PrintingClass(); System.out.print("Type in the character string for printing: "); characterString = reader.nextLine(); printer.Print(characterString); } }
// Write the missing class here
Note: In this exercise the solution is part of a conversion unit where many classes have been declared. Because of this the classes are not declared as public using the public attribute.
Example output
Type in the character string for printing: John Doe
John Doe
My Class: class PrintingClass { public void print(){ System.out.println(characterString); } }
