In this article, we will discuss difference between List and Set in detail i.e.; List v/s Set. Both interfaces directly extends Collection interface

1. List v/s Set:

List	Set
List stores elements according to insertion order So, insertion order is preserved	Set stores elements in random order, as it uses hashing technique Insertion order isn’t preserved
While iterating List items, elements will be retrieved as per insertion order	While iterating Set items, elements will be retrieved in random order
List allows duplicate elements	Set doesn’t allow duplicate elements i.e.; it stores only unique elements Note: if same element is added again, there won’t be any compile-time or runtime error, just that add() method returns false;
Any number of NULL object is allowed to add to the List	Maximum of one NULL is allowed

Q) When to use List ?

If the business requirement is to preserve insertion order and
adding duplicate elements is not a big concern
then List is the good choice to store group of elements
Example: it could be ArrayList or LinkedList or Vector, etc

Q) When to use Set ?

If the business requirement is to avoid storing duplicate elements
And storing only unique elements
Where insertion order isn’t big factor while iterating items
then Set is the good choice to store group of elements
Example: it could be HashSet, etc

2. List Program using ArrayList, LinkedList and Vector :

ListPrograms.java

package in.bench.resources.collection;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Vector;

public class ListPrograms {

	public static void main(String[] args) {

		// create object of ArrayList using List reference
		List<String> arrayList = new ArrayList<String>();
		arrayList.add("Sachin");
		arrayList.add("Sourav");
		arrayList.add("Dravid");
		arrayList.add("Laxman");

		System.out.println("ArrayList elements : "
				+ arrayList);

		// create object of LinkedList using List reference
		List<String> linkedList = new LinkedList<String>();
		linkedList.add("Sehwag");
		linkedList.add("Yuvraj");
		linkedList.add("Zaheer");
		linkedList.add("Harbhajan");

		System.out.println("\nLinkedList elements : "
				+ linkedList);

		// create object of Vector using List reference
		List<String> vector = new Vector<String>();
		vector.add("Kumble");
		vector.add("Srinath");
		vector.add("Azhar");

		System.out.println("\nVector elements : "
				+ vector);
	}
}

Output:

ArrayList elements : [Sachin, Sourav, Dravid, Laxman]

LinkedList elements : [Sehwag, Yuvraj, Zaheer, Harbhajan]

Vector elements : [Kumble, Srinath, Azhar]

3. Set Program using HashSet, LinkedHashSet and TreeSet :

SetPrograms.java

package in.bench.resources.collection;

import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.TreeSet;

public class SetPrograms {

	public static void main(String[] args) {

		// create object of HashSet using Set reference
		Set<String> hashSet = new HashSet<String>();
		hashSet.add("Sachin");
		hashSet.add("Sourav");
		hashSet.add("Dravid");
		hashSet.add("Laxman");

		System.out.println("HashSet elements : "
				+ hashSet);

		// create object of LinkedHashSet using Set reference
		Set<String> linkedHashSet = new LinkedHashSet<String>();
		linkedHashSet.add("Sehwag");
		linkedHashSet.add("Yuvraj");
		linkedHashSet.add("Zaheer");
		linkedHashSet.add("Harbhajan");

		System.out.println("\nLinkedHashSet elements : "
				+ linkedHashSet);

		// create object of TreeSet using Set reference
		Set<String> treeSet = new TreeSet<String>();
		treeSet.add("Kumble");
		treeSet.add("Srinath");
		treeSet.add("Azhar");

		System.out.println("\nTreeSet elements : "
				+ treeSet);
	}
}

Output:

HashSet elements : [Dravid, Laxman, Sourav, Sachin]

LinkedHashSet elements : [Sehwag, Yuvraj, Zaheer, Harbhajan]

TreeSet elements : [Azhar, Kumble, Srinath]

References:

Happy Coding !!
Happy Learning !!

BenchResources.Net

Java tutorial for beginners

1. List v/s Set:

Q) When to use List ?

Q) When to use Set ?

2. List Program using ArrayList, LinkedList and Vector :

ListPrograms.java

Output:

3. Set Program using HashSet, LinkedHashSet and TreeSet :

SetPrograms.java

Output:

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