Java Collections

Java Collections
A List (sometimes called a sequence) is an ordered Collection that can contain duplicate elements. Like array indices, List indices are zero based (i.e., the first element’s index is zero). In addition to the methods inherited from Collection, List provides methods for manipulating elements via their indices, manipulating a specified range of elements, searching for elements and obtaining a ListIterator to access the elements.
Interface List is implemented by several classes, including ArrayList , LinkedList and Vector. Autoboxing occurs when you add primitive-type values to objects of these classes, because they store only references to objects. Classes Array List and Vector are resizable-array implementations of list.
A LinkedList enables efficient insertion or removable of elements in the middle of a collection.
List collection is defined in a java.util.list.
1. Interface
Before we discuss the List, we need to define the Interface.
An interface in Java programming language is an abstract type that is used to specify an interface (in the generic sense of the term) that classes must implement. Interfaces are declared using the interface keyword, and may only contain method signature and constant declarations (variable declarations that are declared to be both static and final). All methods of an Interface do not contain implementation (method bodies) as of all versions below Java 8. Starting with Java 8, default and static methods may have implementation in the interface definition.
As shown in the figure given below, a class extends another class, an interface extends another interface but a class implements an interface.