How to Get a Size of Collection in Java?

Given a Collection in Java, the task is to find the length or size of the collection.

Examples:

Input: Array_List: [1, 2, 3,4]
Output: 4

Input: Linked_List: [geeks, for, geeks]
Output: 3

The Size of the different collections can be found with the size() method. This method returns the number of elements in this collection. This method does not take any parameters.

Below is the Implementation:

Example 1:

Java

// Java program to demonstrate
// size() method of collection

import java.util.*;

public class Example1 {
    public static void main(String[] args)
    {

        // Creating object of List<Integer>
        List<Integer> Array_List = new ArrayList<Integer>();

        // add elements
        Array_List.add(1);
        Array_List.add(2);
        Array_List.add(3);
        Array_List.add(3);

        // getting total size of list
        // using size() method
        int size = Array_List.size();

        // print the size of list
        System.out.println("Size of list = " + size);

        // print list
        System.out.println("Array_List = " + Array_List);
    }
}

Output

Size of list = 4
Array_List = [1, 2, 3, 3]

Example 2:

Java

// Java program to demonstrate
// size() method of Collection
import java.util.*;
import java.io.*;

class Example2 {
    public static void main(String[] args)
    {

        // Creating object of LinkedList<Integer>
        LinkedList<String> al = new LinkedList<String>();

        // Populating LinkedList
        al.add("GEEKS");
        al.add("FOR");
        al.add("GEEKS");

        // getting total size of Linkedlist
        // using size() method
        int size = al.size();

        // print the size
        System.out.println("Size of the linkedlist = "
                           + size);

        // print Linkedlist
        System.out.println("Linkedlist = " + al);
    }
}

Output

Size of the linkedlist = 3
Linkedlist = [GEEKS, FOR, GEEKS]