Java Program to Find the Intersection Between Two Collection

// Java Program to Remove All the Elements from the First
// Collection if it is not Available in the Second
// Using ArrayList.contains() Method  

// Importing input output classes
import java.io.*;
// Importing utility classes
import java.util.*;

// Main class
public class GFG {

    // Method 1 of this class
    // To remove the elements from the collection
    static ArrayList<Integer>
    RemoveElements(ArrayList<Integer> A,
                   ArrayList<Integer> B)
    {
        // Iterating over elements in object
        // using for loop
        for (int i = 0; i < A.size(); ++i) {

            // Removing the elements from the collection
            if (B.contains(A.get(i)) == false) {
                A.remove(i);
            }
        }

        // Returning the update ArrayList
        return A;
    }

    // Method 2 of this class
    // To print the collection
    static void print(ArrayList<Integer> A)
    {
        // Iterating over elements in object
        // using for-each loop
        for (int element : A) {

            // Printing the elements of the linked list
            System.out.print(element + " ");
        }
    }

    // Method 3 of this class
    // Main driver method
    public static void main(String[] args)
    {
        // Creating an object of ArrayList class
        // Declaring object of Integer type
        ArrayList<Integer> A = new ArrayList<>();

        // Inserting elements to ArrayList object
        // Custom input entries
        A.add(1);
        A.add(2);
        A.add(3);
        A.add(4);

        // Creating another object of ArrayList class
        // Again declaring object of Integer type
        ArrayList<Integer> B = new ArrayList<>();

        // Inserting elements to ArrayList object
        // Custom input entries
        B.add(1);
        B.add(2);
        B.add(3);

        // Calling the Function
        ArrayList<Integer> UpdatedCollection
            = RemoveElements(A, B);

        // Lastly printing the updated collection
        print(A);
    }
}

// Java Program to Remove All the Elements from the First
// Collection if it is not Available in the Second
// Using Vector.retainAll() method

// Importing libraries
import java.io.*;
import java.util.*;

// Main class
public class GFG {
    // Method 1 of this class
    // To remove the elements from the collection
    static Vector<Integer> RemoveElements(Vector<Integer> A,
                                          Vector<Integer> B)
    {
        A.retainAll(B);
        // Returning the update ArrayList
        return A;
    }
    // Method 2 of this class
    // To print the collection
    static void print(Vector<Integer> A)
    {
        // Iterating elements in object using for loop
        for (int element : A) {

            // Printing the elements of the linked list
            System.out.print(element + " ");
        }
    }

    // Method 3 of this class
    // Main driver method
    public static void main(String[] args)
    {
        // Creating an ArrayList object
        // Declaring object of integer type
        Vector<Integer> A = new Vector<>();

        // Inserting elements in the ArrayList
        // Custom input entries
        A.add(1);
        A.add(2);
        A.add(3);
        A.add(4);

        // Creating another ArrayList
        // Again declaring object of integer type
        Vector<Integer> B = new Vector<>();

        // Inserting elements in the ArrayList
        // Custom input entries
        B.add(1);
        B.add(2);
        B.add(3);

        // Calling the Method1 now to
        // remove the elements from the collection
        Vector<Integer> UpdatedCollection
            = RemoveElements(A, B);

        // Printing the updated collection
        print(A);
    }
}