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What implements List in Java?
The Java platform contains two general-purpose List implementations. ArrayList , which is usually the better-performing implementation, and LinkedList which offers better performance under certain circumstances.There are two general-purpose List implementations — ArrayList and LinkedList . Most of the time, you'll probably use ArrayList , which offers constant-time positional access and is just plain fast. It does not have to allocate a node object for each element in the List , and it can take advantage of System.Method 1: Creation of List of Lists Using Java 9 List.of() Method

  1. First, create three “String”, “Integer”, and “Double” type Lists named “strList”, “intList”, and “doubleList” using the “List.
  2. Then, create a fourth List with a dynamic type named “parentList” and initialize it with the.
  3. Initialize it with the “List.

How does a List work in Java : Java List is an ordered collection. Java List is an interface that extends Collection interface. Java List provides control over the position where you can insert an element. You can access elements by their index and also search elements in the list.

Why ArrayList implements list in Java

ArrayList inherits AbstractList class and implements the List interface. ArrayList is initialized by size. However, the size is increased automatically if the collection grows or shrinks if the objects are removed from the collection. Java ArrayList allows us to randomly access the list.

How to implement list array Java : To create an array list in Java, you declare an ArrayList variable and call the ArrayList constructor to instantiate an ArrayList object and assign it to the variable: ArrayList friends = new ArrayList(); You can optionally specific a capacity in the ArrayList constructor: ArrayList friends = new ArrayList(100);

The List interface is found in java.util package and inherits the Collection interface. It is a factory of the ListIterator interface. Through the ListIterator, we can iterate the list in forward and backward directions. The implementation classes of the List interface are ArrayList, LinkedList, Stack, and Vector.

Implementations are the data objects used to store collections, which implement the interfaces described in the Interfaces lesson. The Java Collections Framework provides several general-purpose implementations of the core interfaces: For the Set interface, HashSet is the most commonly used implementation.

How to add lists in Java

There are two methods to add elements to the list.

  1. add(E e ) : appends the element at the end of the list. Since List supports Generics , the type of elements that can be added is determined when the list is created.
  2. add(int index , E element ) : inserts the element at the given index .

Internally an ArrayList uses an Object[] Array which is an array of objects. All operation like deleting, adding, and updating the elements happens in this Object[] array. * The array buffer into which the elements of the ArrayList are stored. * will be expanded to DEFAULT_CAPACITY when the first element is added.Below are the following ways to initialize a list:

  • Using List.add() method. Since list is an interface, one can't directly instantiate it.
  • Using Arrays.asList() Creating Immutable List.
  • Using Collections class methods.
  • Using Java 8 Stream.


While Java arrays are fixed in size (the size cannot be modified), an ArrayList allows flexibility by being able to both add and remove elements.

Should I use list or ArrayList : ArrayList class is used to create a dynamic array that contains objects. List interface creates a collection of elements that are stored in a sequence and they are identified and accessed using the index. ArrayList creates an array of objects where the array can grow dynamically.

What is list in Java : The List interface in Java provides a way to store the ordered collection. It is a child interface of Collection. It is an ordered collection of objects in which duplicate values can be stored. Since List preserves the insertion order, it allows positional access and insertion of elements.

Is list and ArrayList same in Java

The List refers to a collection of various elements in a sequence, in which every element is basically an object. Also, we can access these elements by their positions (index). On the other hand, an ArrayList creates an array (dynamic) of the objects that can easily reduce or increase in size as and when required.

the List interface

Class ArrayList<E> Resizable-array implementation of the List interface. Implements all optional list operations, and permits all elements, including null. In addition to implementing the List interface, this class provides methods to manipulate the size of the array that is used internally to store the list.Go to Implementation ⌥⌘B (macOS) / Ctrl+Alt+B (Windows/Linux) can tell you where a method is implemented and take you there.

How does Java implement LinkedList : In Java, the linked list is implemented by the “LinkedList” class. This class belongs to the “java. util” package. The LinkedList class implements the List and Deque interfaces and inherits the AbstractList class.