treeset Questions

8

Solved

I need a Collection that sorts the element, but does not removes the duplicates. I have gone for a TreeSet, since TreeSet actually adds the values to a backed TreeMap: public boolean add(E e) { ...
Pastrami asked 7/3, 2014 at 13:44

6

I want to print an ordered list in Map using the following: Map<Float, String> mylist = new HashMap<>(); mylist.put(10.5, a); mylist.put(12.3, b); mylist.put(5.1, c); SortedSet<Fl...
Korfonta asked 1/2, 2016 at 3:12

2

Solved

If I create an arbitrary class that does not implement Comparable, and try to use it as a treeset, it throws an exception at run time when an object is inserted: public class Foo { } public TreeS...
Micromillimeter asked 15/12, 2012 at 8:15

2

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Let's say I am building a TreeSet of an object for which the ordering depends on only one value. I cannot do TreeSet<Foo> tree = new TreeSet<>(Comparator.comparingInt(Foo::getX)); beca...
Kaylakayle asked 2/10, 2022 at 11:44

3

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Is the computational complexity of TreeSet methods in Java, same as that of an AVLTree? Specifically, I want to know the computational complexity of the following methods: 1.add 2.remove 3.first ...
Midsection asked 17/1, 2013 at 12:49

2

I am looking for time complexity of subset method of treeset. Is it O(n) where n is the number of items in the navigation set ?
Succumb asked 16/3, 2015 at 0:24

11

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What if I want to retrieve and update objects that stored in a TreeSet? The reason I'm asking, is that I want to be able to maintain some data stracture that will store Students. I want it to be s...
Gentry asked 3/12, 2013 at 12:50

3

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I need to use a Tree Set data structure(available in java) in C++, and make use of functions like TreeSet.lower(i) and TreeSet.higher(i) - > which returns the element just lower, and just higher th...
Questionnaire asked 28/4, 2018 at 15:41

5

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I had a interview today and the person taking my interview puzzled me with his statement asking if it possible that TreeSet equals HashSet but not HashSet equals TreeSet. I said "no" but ...
Becca asked 19/6, 2020 at 19:8

14

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I've always loved trees, that nice O(n*log(n)) and the tidiness of them. However, every software engineer I've ever known has asked me pointedly why I would use a TreeSet. From a CS background, I d...
Urbanist asked 23/9, 2009 at 0:11

5

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Here is the piece of code that I have used for Java 5.0 TreeSet<Integer> treeSetObj = new TreeSet<Integer>( Collections.reverseOrder() ) ; Collections.reverseOrder() is used to obtain ...
Diannediannne asked 7/7, 2009 at 8:10

3

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I have a TreeSet which contains > 100k objects. I have another method which requires ArrayList as an param. Is there any way I can accomplish this without iterating whole TreeSet and then adding e...
Rodgerrodgers asked 17/2, 2012 at 3:18

3

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I am trying to merge multiple sorted lists into one TreeSet.. And then I am thinking to apply Binary Search algorithm on that TreeSet to retrieve the element in O(log n) time complexity.. Below is...
Latchet asked 27/2, 2014 at 19:24

5

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I have created a Student class like this: public class Student implements Comparable<Student> { private String firstName; private String lastName; public Student(String firstName, Strin...
Chaunce asked 10/7, 2015 at 7:14

10

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In Java’s documentation for its class TreeSet one of the constructors is shown to have the following header: TreeSet(Comparator<? super E> c) Can someone help explain why there is a construc...
Punctuate asked 17/4, 2015 at 12:22

2

From the following code, I understand that, there is no need of overriding equals() and hashCode() method for TreeSet and TreeMap, neither for sorting, nor searching. public class ComparableTest i...
Contradictory asked 28/2, 2015 at 8:39

6

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I recently came across some Java code that simply put some strings into a Java TreeSet, implemented a distance based comparator for it, and then made its merry way into the sunset to compute a give...
Saddlebow asked 26/4, 2010 at 1:26

1

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Using both Java 8 and Java 11, consider the following TreeSet with a String::compareToIgnoreCase comparator: final Set<String> languages = new TreeSet<>(String::compareToIgnoreCase); l...
Knesset asked 1/1, 2020 at 13:40

8

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I have the following code where I am trying to put the StringBuffer objects as keys in a TreeSet. The reason I do this is to see if I can put mutable objects as keys. I do not get any compile error...
Characharabanc asked 22/8, 2013 at 19:33

7

import java.util.TreeSet; class Test { public static void main(String[] args) { TreeSet t=new TreeSet(); t.add(null); System.out.println(t); } } output: NullPointerException. I read in ma...
Iorgo asked 30/6, 2014 at 11:32

7

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With this code I get this output: TreeSet<String> t=new TreeSet<String>(); t.add("test 15"); t.add("dfd 2"); t.add("ersfd 20"); t.add("asdt 10"); Iterator<String> it=t.it...
Padraig asked 29/4, 2014 at 12:56

8

Maybe I am not using the right data structure. I need to use a set, but also want to efficiently return the k-th smallest element. Can TreeSet in Java do this? There seems no built-in method of Tre...
Nathalie asked 13/1, 2012 at 20:28

2

I'm having some problems with TreeSet: why does this one accept duplicates? I thought TreeSets detected them through the Comparator, and automatically remove them. Please help me, I'm kind of new t...
Panama asked 2/5, 2018 at 23:14

5

What are the advantages of each structure? In my program I will be performing these steps and I was wondering which data structure above I should be using: Taking in an unsorted array and adding...
Lusty asked 23/9, 2010 at 0:9

3

For the code: Set<Phone> set = new TreeSet<>(); set.add(new Phone("Harry")); I get error: Phone cannot be cast to java.base/java.lang.Comparable Why Phone has to implement Comp...
Pardner asked 6/3, 2019 at 10:26

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