Difference between Arrays and Collections

Array

Collection

Arrays are fixed in size.

Collections are growable in nature.

Arrays can contain only homogeneous element types.  

Collections can contain both homogeneous and heterogeneous elements.

The size of the Array needs to be declared at the time of creation.

int[] intArr= new int[10].

Here the size of the integer array is 10.

There is no need to declare the size at the time of creation. We can do that but there is no need.

List list = new ArrayList();

Both primitives and object data types can be stored into an Array.

A collection is only meant for object data types. It cannot store primitives.

To access the element in Array only index notation can be used.

You can use Iterator or various method to access the elements from Collections.

java.util.Arrays class can be used to perform operations like searching, sorting, etc on Arrays.

Similarly, java.util.Collections class can be used to manipulate Collection object.

Arrays are faster and should be preferred when the number of elements to be added to Array is known at the beginning.

When the number of elements is not known then Collection should be used.

Arrays don't provide readymade method support because there is no underlying data structure 

Collections are implemented based on some data structure which provide us with a wide variety of readymade method support.