Java ArrayList

An ArrayList is a resizable list. Unlike an array, it can grow and shrink. You must use object types such as Integer instead of int inside it.

ExampleJava

import java.util.ArrayList;
import java.util.Collections;

public class Main {
  public static void main(String[] args) {
    ArrayList<String> cars = new ArrayList<>();
    cars.add("Volvo");
    cars.add("BMW");
    cars.add("Ford");
    System.out.println(cars);          // [Volvo, BMW, Ford]
    System.out.println(cars.get(1));   // BMW
    cars.set(0, "Audi");
    cars.remove("Ford");
    System.out.println(cars.size());   // 2
    Collections.sort(cars);
    System.out.println(cars);          // [Audi, BMW]

    ArrayList<Integer> nums = new ArrayList<>();
    nums.add(5); nums.add(1); nums.add(3);
    int sum = 0;
    for (int n : nums) sum += n;
    System.out.println("sum = " + sum);
  }
}

Output

[Volvo, BMW, Ford]
BMW
2
[Audi, BMW]
sum = 9

Quick check

What is the advantage of an ArrayList over an array?

It can grow and shrinkIt is always fasterIt stores any type at once

Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.

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