Java ArrayList isEmpty() Method example

The isEmpty() method of java.util.ArrayList class is used to check whether the list is empty or not. This method returns a boolean value. It returns true if the list is empty, and false if the list contains any elements.

Syntax

public boolean isEmpty()

Example

import java.util.ArrayList;

public class ArrayListExample {
    public static void main(String[] args) {
        // Create an empty ArrayList
        ArrayList<String> list = new ArrayList<>();

        // Check if the list is empty or not using isEmpty()
        boolean isEmptyInitially = list.isEmpty();
        System.out.println("Is the list empty initially? " + isEmptyInitially);

        // Add an element to the list
        list.add("Hello");

        // Check if the list is empty after adding an element
        boolean isEmptyAfterAdd = list.isEmpty();
        System.out.println("Is the list empty after adding an element? " + isEmptyAfterAdd);

        // Clear the list (Removing all elements)
        list.clear();

        // Check if the list is empty after clearing
        boolean isEmptyAfterClear = list.isEmpty();
        System.out.println("Is the list empty after clearing? " + isEmptyAfterClear);
    }
}

Output:

Is the list empty initially? true
Is the list empty after adding an element? false
Is the list empty after clearing? true

Explanation

1. Initialization: An ArrayList is created.
2. Initial Check: We check whether the list is empty using isEmpty() method, since the list is not yet initialized, it returns true.
3. Adding Element: We then add an element "Hello" to the list.
4. Check After Adding: We again check the list using isEmpty() method, this time it returns false as the list contains an element.
5. Clearing the List: We delete all the elements of the list using clear() method.
6. Check After Clearing: We again check the list, this time it returns true as the list is empty.