Java Collection Interface

The java.util.Collection interface is a core interface in the Java Collection Framework that represents a group of objects, known as elements. It is used to store, retrieve, and manipulate a collection of elements in a single unit.

The Collection interface extends the Iterable interface, which means that it can be used with the for-each loop to iterate over its elements. It also defines a number of methods for adding, removing, and checking the presence of elements, as well as methods for performing bulk operations on the elements of the collection.

Here is an example of how to use the Collection interface in Java:

import java.util.ArrayList;
import java.util.Collection;

public class Main {
  public static void main(String[] args) {
    Collection<String> collection = new ArrayList<>();

    // Add elements to the collection
    collection.add("apple");
    collection.add("banana");
    collection.add("cherry");

    // Check the size of the collection
    System.out.println("Size: " + collection.size());

    // Check if the collection contains a specific element
    System.out.println("Contains cherry: " + collection.contains("cherry"));

    // Remove an element from the collection
    collection.remove("cherry");

    // Iterate over the elements of the collection
    for (String element : collection) {
      System.out.println(element);
    }
  }
}

In this example, an ArrayList implementation of the Collection interface is used to store a list of strings. The add and remove methods are used to add and remove elements from the collection, and the size and contains methods are used to check the size and presence of elements in the collection. The for-each loop is used to iterate over the elements of the collection and print them to the console.