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Showing content from https://www.geeksforgeeks.org/java/collection-isempty-method-in-java-with-examples/ below:

Collection isEmpty() method in Java with Examples

Last Updated : 24 Jul, 2024

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 return a boolean value indicating whether the collection is empty or not. Here's the correct information for the isEmpty() method:

Syntax:

boolean isEmpty()

Parameters:

This method does not accept any parameter.

Return Value:

This method returns a boolean value, which indicates whether the collection is empty or not. The below examples illustrate the Collection isEmpty() method:

Example 1: Using LinkedList Class Java


 // 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 to 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


 // 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 to 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


 // Java code to illustrate isEmpty() method

import java.io.*;
import java.util.*;

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

        // Create an empty ArrayList with an initial capacity
        Collection<Integer> arrlist = new ArrayList<Integer>(5);

        // Use add() method to add elements to the list
        arrlist.add(15);
        arrlist.add(20);
        arrlist.add(25);

        // Print all the elements available in the 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--

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