This post will discuss different ways to check whether a list is empty in Java. A list is empty if and only if it contains no elements.
1. Using List.isEmpty[] method
The recommended approach is to use the List.isEmpty[] method to check for an empty list in Java. Following is a simple example demonstrating usage of this method:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | import java.util.ArrayList; import java.util.List; class Main { public static void main[String[] args] { List list = new ArrayList[]; if [list == null] { System.out.println["List is null"]; } if [list.isEmpty[]] { System.out.println["List is empty"]; } else { System.out.println["List is not empty or null"]; } } } |
Instead of explicitly checking if the list is null or empty, you can combine the isEmpty[] method with a null check in a single expression, as shown below:
1 2 3 4 5 6 7 8 9 10 11 12 | import java.util.Arrays; import java.util.List; class Main { public static void main[String[] args] { List list = Arrays.asList[1, 2, 3]; if [list == null || list.isEmpty[]] { System.out.println["List is empty or null"]; } } } |
Or, even better:
1 2 3 4 5 6 7 8 9 10 11 12 | import java.util.Arrays; import java.util.List; class Main { public static void main[String[] args] { List list = Arrays.asList[1, 2, 3]; if [list != null && !list.isEmpty[]] { System.out.println["List is not empty"]; } } } |
2. Using List.size[] method
Finally, you can use the List.size[] method, which returns the total number of items in it.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | import java.util.Arrays; import java.util.List; class Main { public static void main[String[] args] { List list = Arrays.asList[1, 2, 3]; if [list != null && list.size[] > 0] { System.out.println["List is not empty"]; } else { System.out.println["List is empty or null"]; } } } |
Thats all about checking whether a list is empty in Java.