Java Collections Framework is a set of interfaces and classes that provides an architecture to store and manipulate groups of objects. It's one of the most powerful features of Java, allowing for efficient data management and manipulation.
Overview
The Java Collections Framework provides a unified architecture for representing and manipulating collections of objects. It includes a range of interfaces and classes, each serving different purposes. The most commonly used interfaces are:
List
: An ordered collection of objects.Set
: A collection of objects that cannot contain duplicate elements.Queue
: A collection used to hold elements prior to processing.Map
: A collection used to store key-value pairs.
Key Components
Interfaces
Collection
: The root interface of the collection hierarchy. It provides the basic methods for manipulating collections.List
,Set
,Queue
,Deque
,Stack
,Map
,SortedSet
,SortedMap
: Specific interfaces for different types of collections.
Classes
ArrayList
,LinkedList
,Vector
,Stack
: Implementations of theList
interface.HashSet
,LinkedHashSet
,TreeSet
: Implementations of theSet
interface.PriorityQueue
,ArrayDeque
: Implementations of theQueue
interface.HashMap
,LinkedHashMap
,TreeMap
,IdentityHashMap
,EnumMap
: Implementations of theMap
interface.
Example Usage
Here's an example of how you can use the ArrayList
class to store and manipulate a list of strings:
import java.util.ArrayList;
public class Main {
public static void main(String[] args) {
ArrayList<String> list = new ArrayList<>();
list.add("Apple");
list.add("Banana");
list.add("Cherry");
System.out.println("First element: " + list.get(0));
System.out.println("Last element: " + list.get(list.size() - 1));
System.out.println("List contains 'Banana': " + list.contains("Banana"));
}
}
Learn More
To learn more about the Java Collections Framework, check out our in-depth guide.
Images
- ArrayList
- LinkedList
- HashSet
- HashMap