Difference between Array and ArrayList in Java

Here you will learn about difference between array and arraylist in java.

Both array and arraylist are most important and frequently used data structure in java. Below I have discussed about various differences between them.

Difference between Array and ArrayList in Java

Property	Array	ArrayList
Size	Array is fixed in size. Once declared, its size can’t be changed.	ArrayList size can be changed after declaration. For example when we add or remove element in arraylist, its size increases or decreases accordingly.
Primitives	Array can contain primitive data types as well as objects.	ArrayList can contain objects only. When we try to add a primitive type element in arraylist then the element is first converted into its corresponding wrapper class and then added. This process of conversion is called auto-boxing.
Performance	Array provides better performance and uses less memory.	ArrayList performance is less and uses more memory as compared to Array. ArrayList internally uses dynamic array for storing elements. Each time an element is added or removed, a new array is created.
Element Type	Array can contain elements of same type.	ArrayList can contain elements of different types.
Iteration	We can iterate through array using loops only.	ArralyList provides various ways for iteration like loops, Iterator and ListIterator class.
Dimension	Array can be single as well as multi-dimensional.	ArrayList is only single dimensional.
Storage	Array elements are stored at contiguous memory locations.	ArrayList elements are not stored at contiguous memory locations.

Array and ArrayList Example in Java

Here I have shared one example that will help you to understand the working of array and arraylist.

import java.util.ArrayList;
import java.util.Iterator;

public class ArrayvsArrayList {
	public static void main(String...s){
		//Array
		int arr[] = new int[3];
		arr[0] = 10;
		arr[1] = 15;
		arr[2] = 20;
		
		for(int i=0;i<arr.length;++i){
			System.out.print(arr[i]+" ");
		}
		
		System.out.println("\n");
		
		//ArrayList
		ArrayList<Integer> arrl = new ArrayList<Integer>();
		arrl.add(10);	//auto-boxing
		arrl.add(15);	//auto-boxing
		arrl.add(20);	//auto-boxing
		
		Iterator it = arrl.iterator();
		while(it.hasNext()){
			System.out.print(it.next()+" ");
		}
	}
}

import java.util.ArrayList;

import java.util.Iterator;

public class ArrayvsArrayList {

public static void main(String...s){

//Array

int arr[] = new int[3];

arr[0] = 10;

arr[1] = 15;

arr[2] = 20;

for(int i=0;i<arr.length;++i){

System.out.print(arr[i]+" ");

}

System.out.println("\n");

//ArrayList

ArrayList<Integer> arrl = new ArrayList<Integer>();

arrl.add(10); //auto-boxing

arrl.add(15); //auto-boxing

arrl.add(20); //auto-boxing

Iterator it = arrl.iterator();

while(it.hasNext()){

System.out.print(it.next()+" ");

}

Output

10 15 20

Comment below if you found anything incorrect in above tutorial for difference between array and arraylist in java.

Difference between Array and ArrayList in Java

Difference between Array and ArrayList in Java

Array and ArrayList Example in Java

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