Difference between set vs list in java: defined method

Safalta Expert Published by: Vanshika Jakhar Updated Wed, 23 Nov 2022 05:04 PM IST

The collection is extended by Java's List and Set interface. They both keep up the collection of things or elements. However, the key distinction between them is that a List is a collection of ordered elements and that the elements are added, removed, or accessed with the aid of an index variable. A set, on the other hand, is a collection of objects that forbids the presence of duplicate elements. List and Set work together in java which struggles with a difference as the List is ordered and contains the same elements but the Set is out of order and contains different elements.
The List implementation classes are LinkedList and Arraylist and the SET  implementation classes are Linkhashset, HashSet and Tree set.
Let's examine some additional distinctions between List and Set interfaces with the aid of the comparison table below.
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Table of Content 
List Definition
LinkedList and an array list
Set Definition

HashSet and TreeSet
The main differences between Java's List and Set 


List Definition

The collection interface is extended by the List interface.

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An ordered group of components or objects is referred to as a list. A list, as opposed to a Set, can have duplicate elements. It also defines some of its own methods, such as index-based get and set methods, in addition to the methods defined in Collection List. The elements specified are added or removed from the index specified in the method argument by the add and remove methods that are inherited from the Collection. A list is a type of array whose size increases as more elements are added.


LinkedList and an Array list

A list can be represented in two obvious ways: as a dynamic array and as a linked list. The collection classes java.util.ArrayList and java.util.LinkedList, respectively, offer both of these choices in generic form. A component of the Java Collection Framework are these classes. Each one implements the interface Collection and, by extension, the interface List. An object of type ArrayList represents an ordered list of objects of type T that are stored in an expanding array that can expand in size as new items are added as needed. Although the objects are stored in nodes that are connected by pointers, an object of type LinkedList still represents an ordered sequence of objects of type T. The standard list operations are supported by both list classes.

Set Definition

The Collection interface is expanded by the Set interface. A set interface is a group or collection of objects without any duplicates. This implies that there cannot be two references to the same object, one reference to two objects, or two references to Null. The elements' sequence or order is unimportant, but that does not mean that the ordered set is forbidden.

HashSet and TreeSet

A set is a group of items where no item appears more than once. Sets implement every method in the Collection interface, but they do so in a way that makes sure no element appears more than once in the set. TreeSet and HashSet are the two Java classes that implement the interface Set.
The elements of a TreeSet are arranged in ascending sorted order, which is one of its properties.
A hash table, a kind of data structure that I will go over in the following section, is where a hash set stores its elements. Even more so than for TreeSets, hash tables are incredibly efficient at finding, adding, and removing elements.

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The main differences between Java's List and Set

While Set does not preserve the order of the elements, there is an exception, List preserves the order of the elements in a collection. The LinkedHashSet preserves the insertion order.

Lists are allowed to have duplicate elements because each element is uniquely identified by its index, but a Set is not allowed to have duplicate elements because it lacks the ability to uniquely identify each object in a collection.

The interfaces ArrayList, LinkedList, CopyOnWriteArrayList, Vector, and Stack implement the list interface. In contrast, the interfaces for HashSet, LinkedHashSet, EnumSet, TreeSet, and CopyOnWriteArraySet implement Set.

In addition to the methods defined in Collection, List also defines some of its own methods. While Set does not define any methods of its own, it does forbid Collection's methods from adding any duplicate elements.

Which is better- list or Set?

The primary distinction between List and Set is that while Set forbids duplicates, List does.


In Java, which is faster, list or set?

When accessing an element, the array is quicker, whereas the list is quicker when adding or removing elements from the collection.


Can duplicates exist in sets?

A Collection that excludes duplicate elements is referred to as a Set. It simulates the abstraction of a set in mathematics.


Why HashSet is faster than TreeSet?

TreeSet is slower than HashSet. A hash table is used to implement the hash set. TreeSet has a higher search, insert, and delete time than HashSet, which is O(Log n). However, TreeSet retains sorted data.

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