Arraylist vs LinkedList vs Vector in java

All ArrayList LinkedList, and Vectors implement the List interface. Both (ArrayList and Vectors) use dynamically resizable arrays as their internal data structure. Whereas both ArrayList and Linked List are non synchronized. But they have several differences also, let us discuss ArrayList, LinkedList and Vectors in details with examples and differences.

Collection Interface

ArrayList:

ArrayList in java, uses dynamic arrays to store its elements and maintains insertion order. ArrayList can store duplicate elements. It is a non synchronized collection type. ArrayList class extends AbstractList and implements the List, RandomAccess, Cloneable, Serializable interfaces.

Note: ArrayList provides the mechanism of random access because of it’s index based nature.

public class ArrayList
extends AbstractList
implements List, RandomAccess, Cloneable, Serializable

Example

import java.io.*; 
import java.util.*; 
 
public class Main 
{ 
	public static void main (String[] args) 
	{ 
		// ArrayList creation
		ArrayList javaDevelopers = new ArrayList(); 
 
		// Adding elements to arraylist 
		javaDevelopers.add("Shivanshu"); 
		javaDevelopers.add("Roxy"); 
		javaDevelopers.add("Ganesh"); 
		javaDevelopers.add("Shailender"); 
 
		// Traversing ArrayList elements
		System.out.println("Java Developrs:"); 
		Iterator iterator = javaDevelopers.iterator(); 
		while (iterator.hasNext()) 
			System.out.println(iterator.next()); 
 
	}
}

Output

Java Developrs:  
Shivanshu 
Roxy
Ganesh
Shailender

LinkedList:

LinkedList in java, uses linked list data structure as it’s internal implementation to store elements. It can store duplicate elements. LinkedList class extends AbstractSequentialList and implements the List, Deque, Cloneable, Serializable interfaces. Like ArrayList, LinkedList is also not synchronized.

Note: LinkedList does not provides any facility like random access. Its performance is better than Arraylist on add and remove operations, but worse on get and set operations.

public class LinkedList
extends AbstractSequentialList
implements List, Deque, Cloneable, Serializable

Example

import java.io.*; 
import java.util.*; 
 
public class Main 
{ 
	public static void main (String[] args) 
	{ 
		// LinkedList creation
		LinkedList javaDevelopers = new LinkedList(); 
 
		// Adding elements to arraylist 
		javaDevelopers.add("Shivanshu"); 
		javaDevelopers.add("Roxy"); 
		javaDevelopers.add("Ganesh"); 
		javaDevelopers.add("Shailender"); 
 
		// Traversing LinkedList elements
		System.out.println("Java Developres:"); 
		Iterator iterator = javaDevelopers.iterator(); 
		while (iterator.hasNext()) 
			System.out.println(iterator.next()); 
 
	} 
}

Output

Java Developrs:  
Shivanshu 
Roxy
Ganesh
Shailender

Vector

Vector class in java, implements a growable or dynamic array of objects. Similar to an array, Vector contains components which can be accessed using an integer index. After the Vector creation, the size of a Vector can grow or shrink as needed to accommodate adding and removing elements. Vector extends AbstractList and implements List, RandomAccess, Cloneable, Serializable interfaces.

public class Vector
extends AbstractList
implements List, RandomAccess, Cloneable, Serializable

Example

import java.io.*; 
import java.util.*; 
 
public class Main 
{ 
	public static void main (String[] args) 
	{ 
 
		// Vector creation 
		Vector javaDevelopers = new Vector(); 
 
		//Adding elements to vector
		javaDevelopers.addElement("Shivanshu"); 
		javaDevelopers.addElement("Roxy"); 
		javaDevelopers.addElement("Ganesh"); 
		javaDevelopers.addElement("Shailender"); 
 
		// Traversing vector elements
		System.out.println("Java Developrs:"); 
		Enumeration enumeration = javaDevelopers.elements(); 
		while (enumeration.hasMoreElements()) 
			System.out.println(enumeration.nextElement()); 
	} 
}

Output

Java Developrs:  
Shivanshu 
Roxy
Ganesh
Shailender

ArrayListor or LinkedList?

ArrayList should be preferred over LinkedList if get and set are much more as compared to adding or removing the elements but if adding or removing operations are higher than get and set operation then LinkedList should be preferred.

Difference between ArrayList and LinkedList

ArrayList	LinkedList
It uses a dynamic array as it’s internal implementation.	It uses doubly linked list as it’s internal implementation.
It is better in get and set operations.	It is better in adding and removing operations.

Performance comparison between ArrayList and LinkedList

Example

import java.io.*; 
import java.util.*; 
 
public class Main 
{ 
	public static void main (String[] args) 
	{ 
		ArrayList<Integer> arrayList = new ArrayList<Integer>();
        LinkedList<Integer> linkedList = new LinkedList<Integer>();
 
        // ArrayList add operation
        long startTime = System.nanoTime();
 
        for (int i = 0; i < 100000; i++) {
        	arrayList.add(i);
        }
        long endTime = System.nanoTime();
        long duration = endTime - startTime;
        System.out.println("Time Taken by ArrayList in add operation: " + duration);
 
        // LinkedList add operation
        startTime = System.nanoTime();
 
        for (int i = 0; i < 100000; i++) {
        	linkedList.add(i);
        }
        endTime = System.nanoTime();
        duration = endTime - startTime;
        System.out.println("Time Taken by LinkedList in add operation: " + duration);
 
        // ArrayList get operation
        startTime = System.nanoTime();
 
        for (int i = 0; i < 10000; i++) {
        	arrayList.get(i);
        }
        endTime = System.nanoTime();
        duration = endTime - startTime;
        System.out.println("Time Taken by ArrayList in get operation: " + duration);
 
        // LinkedList get operation
        startTime = System.nanoTime();
 
        for (int i = 0; i < 10000; i++) {
        	linkedList.get(i);
        }
        endTime = System.nanoTime();
        duration = endTime - startTime;
        System.out.println("Time Taken by LinkedList in get operation: " + duration);
 
        // ArrayList remove operation
        startTime = System.nanoTime();
 
        for (int i = 9999; i >=0; i--) {
        	arrayList.remove(i);
        }
        endTime = System.nanoTime();
        duration = endTime - startTime;
        System.out.println("Time Taken by ArrayList in remove operation:  " + duration);
 
        // LinkedList remove operation
        startTime = System.nanoTime();
 
        for (int i = 9999; i >=0; i--) {
        	linkedList.remove(i);
        }
        endTime = System.nanoTime();
        duration = endTime - startTime;
        System.out.println("Time Taken by LinkedList in remove operation: " + duration);
 
	} 
}

Output

Time Taken by ArrayList in add operation: 12505291 
Time Taken by LinkedList in add operation: 8494106
Time Taken by ArrayList in get operation: 103500 
Time Taken by LinkedList in get operation: 86634134  
Time Taken by ArrayList in remove operation:  252982817 
Time Taken by LinkedList in remove operation: 87576796

Vector or ArrayList?

As ArrayList is non-synchronized and fast, so in single threaded applications ArrayList should be preferred but in multi-threaded applications Vector should be used over ArrayList because of it’s synchronized nature.

Difference between ArrayList and Vector

ArrayList	Vector
It is not synchronized.	It is synchronized.
It is not a legacy class.	It is a legacy class.
It increases its size by 50% of the array size.	It increases its size by doubling the array size i.e. 100%.
Iterator interface is used to traverse the ArrayList elements.	Iterator or Enumeration interface can be used to traverse the Vector elements.
ArrayList is much fast than Vector because it is non-synchronized.	Vector is slow as compared ArrayList because it is synchronized

Java interview questions on collections

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