How to use List size() method in Java? Comes with examples

The List interface extends the Collection interface and stores a sequence of elements. The List interface provides two methods to efficiently insert and delete multiple elements at any point in the list. Unlike sets, lists allow duplicate elements, and if null values ​​are allowed in the list, multiple null values ​​are allowed.

List interface size() can be used to get the number of elements currently present in the list. It always returns the count of currently existing elements. You can check the latest size after adding/removing elements to the list.

Syntax

int size()

Comments

• Returns the number of elements in this list.

• If this list contains more elements than Integer.MAX_VALUE elements, Integer.MAX_VALUE is returned as the size.

Returns

The number of elements in this list.

Example 1

The following example demonstrates how to use the size() method to check the size of a list -

package com.tutorialspoint;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class CollectionsDemo {
   public static void main(String[] args) {
      List<Integer> list = new ArrayList<>(Arrays.asList(1,2,3,4,5,6));
      System.out.println("List: " + list);
      System.out.println("List size: " + list.size());
   }
}

Output

This will produce the following results-

List: [1, 2, 3, 4, 5, 6]
List size: 6

Example 2

The following example shows how to use the size() method to check the size of a list after adding/removing elements -

package com.tutorialspoint;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class CollectionsDemo {
   public static void main(String[] args) {
      List<Integer> list = new ArrayList<>(Arrays.asList(1,2,3,4,5,6));
      System.out.println("List: " + list);
      System.out.println("List size: " + list.size());
     
      list.add(7);
      list.add(8);
      list.add(9);
      System.out.println("List: " + list);
      System.out.println("List size: " + list.size());
     
      list.remove(1);
      System.out.println("List: " + list);
      System.out.println("List size: " + list.size());
   }
}

Output

This will produces the following results -

List: [1, 2, 3, 4, 5, 6]
List size: 6
List: [1, 2, 3, 4, 5, 6, 7, 8, 9]
List size: 9
List: [1, 3, 4, 5, 6, 7, 8, 9]
List size: 8

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