Can you make an array of lists in Java?

Java ArrayList

Java ArrayList class uses a dynamic array for storing the elements. It is like an array, but there is no size limit. We can add or remove elements anytime. So, it is much more flexible than the traditional array. It is found in the java.util package. It is like the Vector in C++.

The ArrayList in Java can have the duplicate elements also. It implements the List interface so we can use all the methods of List interface here. The ArrayList maintains the insertion order internally.

It inherits the AbstractList class and implements List interface.

The important points about Java ArrayList class are:

• Java ArrayList class can contain duplicate elements.
• Java ArrayList class maintains insertion order.
• Java ArrayList class is non synchronized.
• Java ArrayList allows random access because array works at the index basis.
• In ArrayList, manipulation is little bit slower than the LinkedList in Java because a lot of shifting needs to occur if any element is removed from the array list.

Hierarchy of ArrayList class

As shown in the above diagram, Java ArrayList class extends AbstractList class which implements List interface. The List interface extends the Collection and Iterable interfaces in hierarchical order.

ArrayList class declaration

Let's see the declaration for java.util.ArrayList class.

Constructors of ArrayList