What is the ArrayList.isEmpty() method in Java?

The ArrayList.isEmpty() method in Java is used to check if a list is empty. An empty list means that it contains no elements.

Syntax

The ArrayList.isEmpty() method can be declared as shown in the code below:

public boolean isEmpty()

Return value

The ArrayList.isEmpty() method returns a boolean such that:

  • The return value is true if the list is empty.
  • The return value is false if the list is not empty.

Example

Consider the code below, which demonstrates the use of the ArrayList.isEmpty() method:

import java.util.ArrayList;
  
public class Example1 {
    public static void main(String[] args)
    {
        ArrayList<Integer> list1 = new ArrayList<Integer>(5);
        
        boolean empty =  list1.isEmpty();
        System.out.println("list1 is empty: " + empty);
        list1.add(1);
        list1.add(2);
        list1.add(3);
        empty =  list1.isEmpty();
        System.out.println("list1 is empty: " + empty);
    }
}

Explanation

  • A list list1 is declared in line 6.
  • The ArrayList.isEmpty() method is used in line 8 to check if list1 is empty. The ArrayList.isEmpty() returns true because list1 contains no elements.
  • Three elements are added in list1 in lines 11-13 using the add() method.
  • The ArrayList.isEmpty() method is used in line 15 to check if list1 is empty. The ArrayList.isEmpty() returns false because list1 now contains three elements.

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