Removing Duplicates In Array List
Sep 18, 2014
I am stuck on this exercise and I don't know what exactly is wrong. I think it's something with the .remove and the for each loop, but I am not sure.
public class seven {
public static void main(String[] args) {
ArrayList<String> list = new ArrayList<String>();
list.add("aaa");
list.add("brr");
list.add("unni");
[Code] ....
This is what i get
Exception in thread "main" java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
at java.util.ArrayList$Itr.next(Unknown Source)
at seven.removeDuplicates(seven.java:24)
at seven.main(seven.java:18)
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May 6, 2014
I need to call the method to remove duplicates form my array, but it won't let me call the method, or I'm doing it incorrectly which is probably it.
import java.util.*;
public class C_6_15_EliminateDuplicates {
public static void main(String[] args) {
int[] numbers = new int[10];
Scanner input = new Scanner(System.in);
System.out.println("Enter " + numbers.length + " numbers: ");
for (int i = 0; i < numbers.length; i++)
[Code] ......
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Apr 10, 2009
When you "system.out.print(arraylist)" an arraylist, it will give you something like [item1, item2].
Im wondering how I can remove the "[" and "]" brackets fromt he printout, or even if i pass it in as another variable.
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Oct 3, 2014
I am working on a java program that is called OrderedVector which is basically a storage or list that grows and shrinks depending on the amount of data is put in. Most of the methods in my code are correct and working, the only real issue I have lies with either the remove(E obj) method or remove(int index) method. This is the driver I am currently using to test my remove method,
public class Tester {
public static void main(String[] args) {
OrderedListADT<Integer> v;
v = new OrderedVector<Integer>();
for(int i = 0 ; i <= 9; i++){
v.insert(i);
[code]....
the output I am receiving is
Removing 0
Size of data structure is 9
Removing 1
Size of data structure is 8
Removing 2
Size of data structure is 7
[code]....
As you can see, when I am calling the second for loop, none of the elements are being removed by my methods but the first for loop is working just fine.
Here is my code for the OrderedVector
package data_structures;
import java.util.Iterator;
import java.util.NoSuchElementException;
public class OrderedVector<E> implements OrderedListADT<E>{
private int currentSize, maxSize;
private E[] storage;
public OrderedVector(){
currentSize = 0;
[code]....
So overall, my remove method should implement binary search and remove elements using either an index or the object value type.
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Apr 11, 2014
Im not sure why the nodes are not being deleted. Is a part of my logic wrong?
public void delete(String s) {
Node temp = find(s);
if (temp==null) {
return;
}
Node prevTemp = temp.prev;
Node nextTemp = temp.next;
[Code] .....
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Nov 2, 2014
THE PROGRAM DOES NOT HAVE ERRORS. FILL THE 2D ARRAY WITHOUT DUPLICATES VALUES. AND DISPLAY IF THE ARRAY IS MAGIC SQUARE OR NOT.
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Jan 23, 2013
It's supposed to count all of the duplicates in an array and print out how many occurrences of the value starting at whatever index, or if there are no duplicates state that. Basically:
No duplicates with value 1 beyond Index 0
There are 3 more occurrences of value 2 starting at index 1
There are 2 more occurrences of value 2 starting at index 2....
This is what I've got so far:
Java Code:
public static void main(String[] args) {
int[] arr = {1, 2, 2, 3, 4, 2, 4, 3, 0, 5, 3, 2};
for(int i = 0; i<arr.length; i++){
int count = 0;
for(int j = i+1; j<arr.length; j++){
if((arr[j] == arr[i]) && (i!=j)){
count++;
System.out.print("There are " + count + " more occurrences of ");
System.out.println(arr[i] + " starting at index " + i);
}
}
}
} mh_sh_highlight_all('java');
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Apr 12, 2015
I have taken array int[] a = {33,33,5,5,9,8,9,9};
In this array so many values are duplicates means 33 comes twice & 5 also comes twice & 9 comes three times. But I want to count the first value which is duplicate means 33 is first value which comes twice so answer would be 2.
I try:
public class FindFirstDuplicate {
public static void main(String[] args) {
int c=0;
int[] a = {33,33,5,5,9,8,9,9};
outerloop:
for(int i = 0; i < a.length; i++) {
[code]....
Output:
33
Count: 1
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Apr 16, 2014
This code is not best way to find the duplicate elements in a given array. Any alternative method for an optimized code.
Java Code:
import java.util.Arrays;
public class Find_Dupliicate_ArrayElement {
public static void main(String[] args) {
int[] Array1 = {1, 9,8,1,2,8,9,7,10, -1, 1, 2, 3, 10, 8, -1};
// Store the array length
int size = Array1.length;
//Sort the array
Arrays.sort(Array1);
[code]....
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Mar 20, 2014
public class werek4d {
public static void main(String[] args) {
int counter = 1;
int[] anArray = new int[101] ;
for (int i = 0; i <= 99; i++){
anArray[i] = i + 1;
System.out.println(i + ": " + anArray[i] + " ");
[Code] ....
My aim is to generate a lists containing 1 to 100. I will then count the number of integers divisible by 3. After doing so, I want to delete the integers that are NOT divisible by 3 in the lists. I tried doing it, but I seem to keep on getting the same lists.
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Dec 18, 2014
I was trying remove duplicates element from my array without using collection API but i didn't got any output from my code.Although it is compiled successfully but on execution it didn't give any output. I guess there must be some problem in function Duplicate
Java Code:
class Union {
public static void main(String...s) {
Union M=new Union();
int x[]=new int[]{1,0,1,4,10,10,10,3,567,4,3,33};
int y[]=new int[]{5,4,5,4,5,4,2,3,3,1,0};
int []w=M.merge(x,y);
[Code] .....
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Jul 20, 2014
Ask the user to enter a sequence of at most 20 nonnegative integers. Your program should have a loop that reads the integers into an array and stops when a negative is entered (the negative number should not be stored). Invoke the average method to find the average of the integers in the array (send the array as the parameter).
how can I remove the negative number from the array and calculate the average of the posive elements without the negative ones? This is my code so far...
import java.util.Scanner;
import javax.swing.JApplet;
public class Parameters
{
//-------------------------------------
//Calls the average and minimum methods
//with different numbers of parameters
[code]....
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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();
[Code] ....
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Jun 8, 2014
Question 1: I am working on an assignment where I have to remove an item from a String array (see code below). When I try to remove an item after entering it I get the following error "java.lang.NullPointerException." I am not sure how to correct this error.
Question 2: In addition, I am having trouble figuring out how to count the number of occurrences of each string in the array and print the counts. I've been looking at other posts but they are more advanced and I have not yet learned how to use some of the tools they are referring to.
private void removeFlower(String flowerPack[]) {
// TODO: Remove a flower that is specified by the user
Scanner input=new Scanner(System.in);
System.out.println();
System.out.println("Please enter the name of the flower you would like to remove:
[Code] ....
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May 14, 2015
I'm trying to count the number of elements in an ArrayList which also have duplicates. So for example, in an ArrayList of strings which contains cat, cat, dog, horse, zebra, zebra, the answer should be two.
If an element is found to be a duplicate, that element should then be exempt from the search so if that element is found again it should not increase the duplicate count.
Here is my code:
public int countDuplicates() {
int duplicates = 0;
// TODO: Write the code to get the number of duplicates in the list
for (int i = 0; i < list.size()-1;i++) {
boolean found = false;
[Code] ....
I know it's wrong because right now it's still increasing the duplicate count for elements that have already been detected as duplicates. How can I make it stop doing this?
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Apr 11, 2014
Write a method compressDuplicates that accepts a stack of integers as a parameter and that replaces each sequence of duplicates with a pair of values: a count of the number of duplicates, followed by the actual duplicated number. For example, suppose a variable called s stores the following sequence of values:
bottom [2, 2, 2, 2, 2, -5, -5, 3, 3, 3, 3, 4, 4, 1, 0, 17, 17] top
If we make the call of compressDuplicates(s);, after the call s should store the following values:
bottom [5, 2, 2, -5, 4, 3, 2, 4, 1, 1, 1, 0, 2, 17] top
This new stack indicates that the original had 5 occurrences of 2 at the bottom of the stack followed by 2 occurrences of -5 followed by 4 occurrences of 3, and so on. This process works best when there are many duplicates in a row. For example, if the stack instead had stored:
bottom [10, 20, 10, 20, 20, 10] top
Then the resulting stack after the call ends up being longer than the original:
bottom [1, 10, 1, 20, 1, 10, 2, 20, 1, 10] top
If the stack is empty, your method should not change it. You may use one queue as auxiliary storage to solve this problem. You may not use any other auxiliary data structures to solve this problem, although you can have as many simple variables as you like. You may not use recursion to solve this problem. For full credit your code must run in O(n) time where n is the number of elements of the original stack.
I wrote a code but still having a problem with it , am I allowed to use 3 while loops ?
public void compressDuplicates(Stack<Integer> s ){
Stack<Integer> backup= new Stack<Integer>();
int count = 1;
while(!s.isEmpty()){
int temp = s.pop();
[Code] .....
// example 1
Expected output : bottom [5, 2, 2, -5, 4, 3, 2, 4, 1, 1, 1, 0, 2, 17] top
My output: //bottom [17, 2, 2, 2, 2, 2, -5, -5, 3, 3, 3, 3, 4, 4, 1, 0, 17, 17] top
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Nov 5, 2014
I'm struggling with that piece of code, my intention is to check for the object I want to add before adding it, so there won't be any duplicate on my list. I'm not sure how could I do that, since I'm working with objects.
Person is a class with few parameters such as id, name, and few others.
I guess I should search for a person with the same id, since that has be unique, but can't get it right.
private ArrayList<person> model= new ArrayList<>();
//...
if (model.contains(person))throw new IllegalArgumentException("duplicate");
else model.addElement(person);
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Apr 20, 2014
I have a HashSet, which I created to prevent duplicates upon output, but of course it's printing duplicates(or else I wouldn't be posting this). The order of my output does not matter, nor the input. The data type is String in the format (x + "," + z), where x and z are integers, creating a collection of coordinate sets. So to prevent the output of duplicates, I'm trying to get rid of the duplicates before they are added to the collection.
I've tried doing a '.equals()' string comparison but what happens is, since my string is added via one variable, it compares itself to itself and if itself equals itself it won't be added to the collection. I really need to keep this as a comparison of a single variable, because creating a key for each value would be sooo ridiculous for this volume of inputs.
So, with that being said, I would like to add one copy of the string, discard the duplicates, and do this thousands of times..
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Oct 16, 2014
How do you format an arraylist?
Mine looks like this:
[<?xml version="1.0" encoding="UTF-8" standalone="no"?> <DefEnv id="Dev">, <Envt id="Test">, , <DB id="DM">,
But I want it to look like: I'd prefer if the '[' , '<>' and ',' were not on them also but I'm not too bothered about that bit.
[<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<DefEnv id="Dev">,
<Envt id="Test">, ,
<DB id="DM">, ]
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Apr 5, 2014
I am creating a hangman game and I want to read in a list of words from a text file, but after the user inputs the name of the text file. I get 'Exception in thread "main" java.lang.NullPointerException'.
Here is the code, where I think the problems lie.
public void runModel(){
ArrayList<String> pirateWordsList = new ArrayList<String>();
System.out.println("What is the name of the file you would like to load? (The file included is called piratewords.txt'");
Scanner in=new Scanner(System.in);
String file=in.next();
load(file);
[Code] ....
The full error message is this:
Exception in thread "main" java.lang.NullPointerException
at uk.ac.aber.dcs.pirate_hangman.Model.load(Model.jav a:108)
at uk.ac.aber.dcs.pirate_hangman.Model.runModel(Model .java:45)
at uk.ac.aber.dcs.pirate_hangman.Main.main(Main.java: 6)
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Feb 2, 2015
I have 3 classes Pet, Cat and Dog classes. Cat and Dog classes are childs of Pet class.
Each pet has the properties of
private String myName;
private int myX;
private int myY;
private int mySpeed;
private int myAge;
I have an array list which creates 100 dogs. How can I print out the dogs with the two highest age values?
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Nov 23, 2014
Im trying to create a program in which I read line by line the contents of a text file, and then report each letter along with its frequency. I was wondering how to read through the lines and process it so that my program knows to increase by a number each time a letter appears in my text file. For example, if A appears in my file 5 times, B 3 times, and C 0 times I want to eventually print out
A -- 5
B-- 3
C-- 0
My first thought was to do this using array lists but is there any way I could do this without using one?
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Apr 28, 2015
method called []getLetterGrades but the only hint My professor told me was that I needed to declare another array list for this method and he wouldnt tell me anything else so bummer. But I don't understand why if what we are returning is a char. It would make sense to return an array list of char to get letter grade. Which is what i did but since the function is a char, the array list character wont work as a return.Primarily i would like to know the type that is needed. I just want an explanation for an array list in this method and how it would serve in this method.
import java.io.File;
import java.util.ArrayList;
import java.util.InputMismatchException;
import java.util.Scanner;
[code]....
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Jun 29, 2014
Directions: public static void initialize(ArrayList names, ArrayList sores)
You should write a function that sorts both array lists, based on the values in the scores array list. This is one of the more conceptually challenging parts of the assignment. You want to sort the scores array list, and simultaneously alter the names array list so that the names continue to line up with their respective scores by index. In the example data above, when the score 9900 moves to the first element of the scores array list, the name "Kim" should also be moved to the top of the names array list. The function should have the following signature:
I'm having trouble figuring out how to sort the lists.
import java.util.ArrayList;
import java.util.Scanner;
public class Assignment5
{
/**
*/
public static void main(String[]args) {
intializeArrays();
[Code] ....
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Mar 28, 2014
I had to write a program that prompts the cashier to enter all prices and names, adds them to two arrays lists, calls the method that I implemented, and displays the result and use 0 as the sentinel value. I am having difficulty coming up with a for loop in the method, I believe I have the condition right but I am having trouble with the statements. I now know that String does not have the get property, but I have only done examples with integers and I am not very good with for loops and wouldn't know how to fix it.
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
ArrayList<Double> sales = new ArrayList<Double>();
ArrayList<String> names = new ArrayList<String>();
System.out.print("Enter Number of Customers");
double salesAmount;
System.out.print("Enter Sales for First Customers");
salesAmount = in.nextDouble();
while(salesAmount != 0)
[code]....
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Nov 30, 2014
I'm trying to remove duplicates from table. I want to remove only those rows which are both id and data equal. My code failed at fourth line.
int i=jTable1.getSelectedRow();
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
jXDatePicker1.setFormats(dateFormat);
String date = dateFormat.format(jXDatePicker1.getDate()).toString();
String c1=jTable1.getValueAt(i, 0).toString();
String c2=jTable1.getValueAt(i, 1).toString();
[Code] .....
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