Java ArrayList size() Method

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Description

The Java ArrayList size() method returns the number of elements in this list i.e the size of the list. It is updated everytime a change is made to the ArrayList.

Declaration

Following is the declaration for java.util.ArrayList.size() method

public int size()

Parameters

NA

Return Value

This method returns the number of elements in this list.

Exception

NA

Getting Size of an ArrayList of Integers Example

The following example shows the usage of Java ArrayList size() method. We're adding couple of Integers to the ArrayList object using add() method calls per element. Size of the arraylist is printed using size() method. And using remove(index) method, we're removing one element and size of the arraylist is again printed.

package com.tutorialspoint;

import java.util.ArrayList;

public class ArrayListDemo {
   public static void main(String[] args) {
      
      // create an empty array list 
      ArrayList<Integer> arrayList = new ArrayList<>();

      // use add() method to add elements in the arrayList
      arrayList.add(20);
      arrayList.add(30);
      arrayList.add(20);
      arrayList.add(30);
      arrayList.add(15);
      arrayList.add(22);
      arrayList.add(11);

      // let us print the size of the arrayList again
      System.out.println("Arraylist Size = " + arrayList.size());
	  
      // remove an element at index 2
      arrayList.remove(2);

      // let us print the size of the arrayList again
      System.out.println("Arraylist Size = " + arrayList.size());
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Arraylist Size = 7
Arraylist Size = 6

Getting Size of an ArrayList of Strings Example

The following example shows the usage of Java ArrayList size() method. We're adding couple of Strings to the ArrayList object using add() method calls per element. Size of the arraylist is printed using size() method. And using remove(index) method, we're removing one element and size of the arraylist is again printed.

package com.tutorialspoint;

import java.util.ArrayList;

public class ArrayListDemo {
   public static void main(String[] args) {
      
      // create an empty array list
      ArrayList<String> arrayList = new ArrayList<>();

      // use add() method to add elements in the arrayList
      arrayList.add("Welcome");
      arrayList.add("To");
      arrayList.add("Tutorialspoint");

      // let us print the size of the arrayList again
      System.out.println("Arraylist Size = " + arrayList.size());
	  
      // remove an element at index 2
      arrayList.remove(2);

      // let us print the size of the arrayList again
      System.out.println("Arraylist Size = " + arrayList.size());    
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Arraylist Size = 3
Arraylist Size = 2

Getting Size of an ArrayList of Objects Example

The following example shows the usage of Java ArrayList size() method. We're adding couple of Student objects to the ArrayList object using add() method calls per element. Size of the arraylist is printed using size() method. And using remove(index) method, we're removing one element and size of the arraylist is again printed.

package com.tutorialspoint;

import java.util.ArrayList;

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

      // create an empty arrayList
      ArrayList<Student> arrayList = new ArrayList<>();

      // use add() method to add elements in the arrayList
      arrayList.add(new Student(1, "Julie"));
      arrayList.add(new Student(2, "Robert"));
      arrayList.add(new Student(3, "Adam"));
	  
      // let us print the size of the arrayList again
      System.out.println("Arraylist Size = " + arrayList.size());
	  
      // remove an element at index 2
      arrayList.remove(2);

      // let us print the size of the arrayList again
      System.out.println("Arraylist Size = " + arrayList.size());      
   }
}

class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Arraylist Size = 3
Arraylist Size = 2