The isEmpty() of java.util.Collection interface is used to check if the Collection upon which it is called is empty or not. This method does not take any parameter and does not returns any value.
Syntax:
Collection.isEmpty()
Parameters: This method do not accept any parameter
Return Value: This method does not return any value.
Below examples illustrate the Collection isEmpty() method:
Example 1: Using LinkedList Class
// Java code to illustrate boolean isEmpty() method import java.io.*;import java.util.*; public class GFG { public static void main(String args[]) { // creating an empty LinkedList Collection<String> list = new LinkedList<String>(); // use add() method to add elements in the list list.add("Geeks"); list.add("for"); list.add("Geeks"); // Output the present list System.out.println("The list is: " + list); // Check if list is empty // using isEmpty() method System.out.println("Is the LinkedList empty: " + list.isEmpty()); // Clearing the LinkedList list.clear(); // printing the new list System.out.println("The new List is: " + list); // Check if list is empty // using isEmpty() method System.out.println("Is the LinkedList empty: " + list.isEmpty()); }} |
Output:
The list is: [Geeks, for, Geeks] Is the LinkedList empty: false The new List is: [] Is the LinkedList empty: true
Example 2: Using ArrayDeque Class
// Java code to illustrate isEmpty() method import java.util.*; public class ArrayDequeDemo { public static void main(String args[]) { // Creating an empty ArrayDeque Collection<String> de_que = new ArrayDeque<String>(); // Use add() method to add elements into the Deque de_que.add("Welcome"); de_que.add("To"); de_que.add("Geeks"); de_que.add("4"); de_que.add("Geeks"); // Displaying the ArrayDeque System.out.println("ArrayDeque: " + de_que); // Check if ArrayDeque is empty // using isEmpty() method System.out.println("Is the ArrayDeque empty: " + de_que.isEmpty()); // Clearing the ArrayDeque de_que.clear(); // printing the new ArrayDeque System.out.println("The new ArrayDeque is: " + de_que); // Check if ArrayDeque is empty // using isEmpty() method System.out.println("Is the ArrayDeque empty: " + de_que.isEmpty()); }} |
Output:
ArrayDeque: [Welcome, To, Geeks, 4, Geeks] Is the ArrayDeque empty: false The new ArrayDeque is: [] Is the ArrayDeque empty: true
Example 3: Using ArrayList Class
// Java code to illustrate isEmpty() method import java.io.*;import java.util.*; public class ArrayListDemo { public static void main(String[] args) { // create an empty array list with an initial capacity Collection<Integer> arrlist = new ArrayList<Integer>(5); // use add() method to add elements in the list arrlist.add(15); arrlist.add(20); arrlist.add(25); // prints all the elements available in list System.out.println("ArrayList: " + arrlist); // Check if list is empty // using isEmpty() method System.out.println("Is the ArrayList empty: " + arrlist.isEmpty()); // Clearing the ArrayList arrlist.clear(); // printing the new ArrayList System.out.println("The new ArrayList is: " + arrlist); // Check if ArrayList is empty // using isEmpty() method System.out.println("Is the ArrayList empty: " + arrlist.isEmpty()); }} |
Output:
ArrayList: [15, 20, 25] Is the ArrayList empty: false The new ArrayList is: [] Is the ArrayList empty: true
Reference: https://docs.oracle.com/javase/9/docs/api/java/util/Collection.html#isEmpty–
