Menu
×
   ❮     
HTML CSS JAVASCRIPT SQL PYTHON JAVA PHP HOW TO W3.CSS C C++ C# BOOTSTRAP REACT MYSQL JQUERY EXCEL XML DJANGO NUMPY PANDAS NODEJS R TYPESCRIPT ANGULAR GIT POSTGRESQL MONGODB ASP AI GO KOTLIN SASS VUE DSA GEN AI SCIPY AWS CYBERSECURITY DATA SCIENCE
     ❯   

Java Tutorial

Java HOME Java Intro Java Get Started Java Syntax Java Output Java Comments Java Variables Java Data Types Java Type Casting Java Operators Java Strings Java Math Java Booleans Java If...Else Java Switch Java While Loop Java For Loop Java Break/Continue Java Arrays

Java Methods

Java Methods Java Method Parameters Java Method Overloading Java Scope Java Recursion

Java Classes

Java OOP Java Classes/Objects Java Class Attributes Java Class Methods Java Constructors Java Modifiers Java Encapsulation Java Packages / API Java Inheritance Java Polymorphism Java Inner Classes Java Abstraction Java Interface Java Enums Java User Input Java Date Java ArrayList Java LinkedList Java List Sorting Java HashMap Java HashSet Java Iterator Java Wrapper Classes Java Exceptions Java RegEx Java Threads Java Lambda Java Advanced Sorting

Java File Handling

Java Files Java Create/Write Files Java Read Files Java Delete Files

Java How To's

Add Two Numbers Count Words Reverse a String Sum of Array Elements Convert String to Array Sort an Array Find Array Average Find Smallest Element ArrayList Loop HashMap Loop Loop Through an Enum Area of Rectangle Even or Odd Number Positive or Negative Square Root Random Number

Java Reference

Java Reference Java Keywords Java String Methods Java Math Methods Java Output Methods Java Arrays Methods Java ArrayList Methods Java LinkedList Methods Java HashMap Methods Java Scanner Methods Java Iterator Methods Java Errors & Exceptions

Java Examples

Java Examples Java Compiler Java Exercises Java Quiz Java Server Java Certificate


Java ArrayList trimToSize() Method

❮ ArrayList Methods


Example

Reduce the capacity of a list to exactly the size of the list:

import java.util.ArrayList;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> cars = new ArrayList<String>();
    cars.add("Volvo");
    cars.add("BMW");
    cars.add("Ford");
    cars.add("Mazda");
    cars.trimToSize();
    System.out.println(cars);
  }
}

Try it Yourself »


Definition and Usage

The trimToSize() method reduces the capacity of a list to fit exactly the number of items that the list contains.

This method does not have a visible effect but it can can be used to reduce the memory usage of the list.

When an ArrayList is created, capacity for 10 items is reserved unless another number is specified in the constructor. Even if the list does not have 10 items, this space is still reserved. Removing items from a list may leave the space for those items reserved. When you are not using of the capacity of an ArrayList then there is some wasted memory which can accumulate if your program makes use of many ArrayLists. You can use the trimToSize() method to recover the unused memory.


Syntax

public void trimToSize()

Related Pages

Java Arrays Tutorial

Java ArrayList Tutorial


❮ ArrayList Methods
×

Contact Sales

If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail:
sales@w3schools.com

Report Error

If you want to report an error, or if you want to make a suggestion, send us an e-mail:
help@w3schools.com

W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use, cookie and privacy policy.

Copyright 1999-2024 by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3.CSS.