Avoid Duplicates On ArrayList
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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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 7, 2014
I'm writing an IRC server in Java, however when a client tries to connect I get a ConcurrentModificationException trying to add them to an ArrayList. My code is Here: [URL]
I don't understand why I am getting a ConcurrentModificationException or what one is.
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May 3, 2014
I have been playing around with my code, but how to avoid NullPointerexception.. So my program's point is simple, use Jsoup to scrape html of certain webpage, then i search the things i want and print them out. Problem is, when scraped html doesnt contain even 1 thing on my search list, i get NullPointerException... i understand why, Heres part of my code:
Java Code:
//Things i need to search from html
String[] MySearchArray = new String[]{"138","146","474"};
//Search things contained in MySearchArray and print them out
for (String Ml : MySearchArray) {
Element flights = doc.select(String.format("tr:contains(%s)", Ml)).first();
Elements flights2 = flights.select("td");
System.out.println(flights2.get(4).text() + " " + flights2.get(0).text()+ " " + flights2.get(3).text());
} mh_sh_highlight_all('java');
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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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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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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 24, 2014
I have a HashMap with multiple values at runtime. In that map one key has empty value , how to avoid this value to add in a list. some code sample is below:
public HashMap getLoop2Map(Map map, String xslFile , int sheetNo){
HashMap hashMap = new HashMap();
try{
ArrayList list = new ArrayList();
System.out.println("-------Map : " +map);
list.add(map.values());
//System.out.println("------- boolean : " +val);
System.out.println("------List : " +list);
}
I do not want to add the empty value in a list ...
result in map
-------Map : {Free Text Entry={},
Mouth / Throat={Free Text Entry={Free Text Entry=<FORMFILENAME>EditChartPhysicalExamText.form
</FORMFILENAME><TAG>"<MUSCULOSKELETAL.PE>"</TAG>},
Salivary Glands Condition={Salivary Glands Condition=MouthAttribute},
Examination Overview- Mouth / Throat={Examination Overview- Mouth / Throat=MouthAttribute},
Tonsils={Tonsils=MouthAttribute},
[Code] ....
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Jul 25, 2014
is it possible to avoid deadlock while coding..
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Feb 12, 2014
How to avoid hard coded href url .
For example a href="www.yahoo.com">
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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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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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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 8, 2014
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import java.awt.event.ActionEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.AbstractAction;
import javax.swing.Action;
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import javax.swing.KeyStroke;
[code]....
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Oct 18, 2014
how to avoid getting negative numbers of coins, use casting and mod to show how many quarters, dimes, nickels, and pennies there are?
import java.util.Scanner;
public class VM
{
public static void main(String[] args)
{
//money deposit
Scanner input = new Scanner(System.in);
[code]....
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Jun 17, 2014
I have code which query value from database,the use case is the user can enter value as 1,01,11 in database but when the user enter value in xml file he can only enter 11,01,12 in database there is two columns lets say column test1=1 and test2=2 combination of this is 12,which is the value the use will enter in xml, but sometime the use can enter test1=04 than column test2=00 ....
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Dec 9, 2014
I'm using EclipseLink, WildFly, EJB, postgresSQL and JSF.I'm trying to persist some countries and their localities.So I've:
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- Abstract Session beans for entity classes: AbstractFacade providing basic crud methods and entity manager.
- Two concrete session bean for entity classes: CountriesFacade and LocalitiesFacade.
- A JSF managed bean named geoJSF.
- A JSF page with a form allowing to insert new country and localities.
In geoJSF I'm injecting via EJB CountriesFacade as property named cf and LocalitiesFacade as property named lf.For the actual inserting country and locality I'm using geoJSF.country and geoJSF.locality. When the form is submitted I'm simply doing:
this.cf.create(this.country);
this.locality.setCountry(this.country); //<- this throw an exception (unique constraint violation) due to the attempt to reinsert this.country
this.lf.create(this.locality);
I disabled all cascade among relations definitions.Based on what I know this.country should appear detached to entity manager so, setting relation the entity manager try to re-persist it.
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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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Apr 30, 2015
How to sort data from a .csv file. The file has a column that contains duplicate groups, and a column that has duplicate employee id's. I need to take the data and sort it into rows. The employee's id will be in the first column, then the groups the employees belong in will occupy the following columns. The groups and employees are dynamic.
groups| empId
-----------------
Group A| a1234 |
Group A| e3456 |
Group A| w3452 |
Group A| d3456 |
Group A| j7689 |
[Code] ....
I want to format the .csv as follows:
--------------------------
empId | group 1 | group 2 |
--------------------------
a1234 | group A | group B |
---------------------------
w3452 | group A | group B |
---------------------------
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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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Nov 5, 2014
Say You have the following values in a stack
indent
escape
indent
paragraph
backtick
My requirement is to put in all unique strings and remove duplicates from the stack.The comparison has to be done only in Stacks.Use of any other Arrays ,Hash tables to store values or comparing is Prohibited.what is the minimum number of stacks required.
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Jul 11, 2014
The keys in a HashMap and the values in a Set must all be unique, but this can be circumvented when using custom objects in a HashMap and Set, because the compiler has no way to determine if the objects are equal or not, as shown in the example below:
Java Code:
import java.util.LinkedHashMap;
import java.util.Map;
public class HashCodeEquals {
public void run(){
Person p1 = new Person(1, "John");
Person p2 = new Person(2, "Matt");
Person p3 = new Person(1, "John");
[code]....
Obviously the equals method is needed because that compares the two objects. But why is the hashCode method needed?
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Jan 12, 2014
Write a program to copy file from c: drive to another drive and avoid duplication??????????
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Jul 28, 2014
I am trying to call another swing frame from my current frame. And after calling second frame i dispose the current frame.
But while second frame coming on the screen, current frame gets dispose and second frame takes some seconds to appear on screen.
So its creating a bad flickering effect on screen and its not suitable for my application.
I want that first frame will call sencond frame and it will not look like second frame is called. I just want to cancel flickering effect.
Here is my source code.
1st Frame:
public class Welcome extends JFrame {
JFrame f;
JTextArea nameField,nameField1;
JLabel lable;
[Code] .....
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Feb 16, 2015
The method I am trying to successfully write is startsWith(String s1, String s2)
The intention of the code is to return true if s2 starts with the string s1, and false otherwise. For example,
x.startsWith("Maplestory","Maple"); Should return true.
This code partially works, depending on the values entered into it. When it is supposed to return true, it does do this. When it is meant to return false, I get a StringIndex OutOfBounds Exception.
public class CC02{
String remove1(char c, String s){
String to_return="";
while(true){
if(s.equals(""))
return to_return;
[Code] ....
The method I have written uses one other method from my code, which is "reverse". Any way to return false without getting this error.
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