Java Collection

In java, the term collection refers to a framework that provide an architecture to store and manipulate a group of objects. These collections

can be used to store, retrieve, manipulate and communicate aggregate data. The collection framework is part of the ‘java. util’ package and is a unified architecture for representing and manipulating collections.

There are key interfaces :

Collection Interface:

the root interface for the collection structure.

It is also an used sub interfaces . List, queue, set, deque.

List interfaces:

Ordered collection.

allows the duplicate elements.

common implementations. ‘Array list’, linked list , vector.

Set interface:

A collection that does not allow duplicate elements.

Common implementations, hash set, tree set.

Deque interface:

double ended queue that allows insertion and removal from both ends

common implementations array deque linkedlist

Queue interface:

designed for holding elements prior to processing

typically orders elements in a fifo.

import java.util.ArrayList;
import java.util.List;

public class ArrayListExample {
    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("Apple");
        list.add("Banana");
        list.add("Orange");

        for (String fruit : list) {
            System.out.println(fruit);
        }
    }
}

Characteristics of Collections

• Generic: Collections in java are generic they can hold objects of any type specified at runtime.
• Dynamic: Many collections classes can dynamically grow and shrink in size.
• Heterogeneous: Collections can store objects of different types, although using generics ensures type safety by allowing collections to be type specific.
• Utility Methods: The collections utility class provides static methods for common operationslike sorting, searching and synchronization.

 

import java.util.ArrayList;
import java.util.List;

public class CollectionExample {
    public static void main(String[] args) {
        // Create a list to store strings
        List<String> fruits = new ArrayList<>();
        
        // Add elements to the list
        fruits.add("Apple");
        fruits.add("Banana");
        fruits.add("Cherry");
        
        // Iterate over the list
        for (String fruit : fruits) {
            System.out.println(fruit);
        }
    }
}