Check out example codes for "java create arraylist". It will help you in understanding the concepts better.

Code Example 1

//create ArrayList
ArrayList<String> arrayList = new ArrayList<String>();
//add item to ArrayList
arrayList.add("item");
//check if ArrayList contains item (returns boolean)
System.out.println(arrayList.contains("item"));
//remove item from ArrayList
arrayList.remove("item");

Code Example 2

List<Integer> list = new ArrayList<>();

Code Example 3

ArrayList<Integer> integerArray = new ArrayList<Integer>();
ArrayList<String> stringArray = new ArrayList<String>();
ArrayList<Double> doubleArray = new ArrayList<Double>();
//... keep replacing what is inside the <> with the appropriate
//data type

Code Example 4

List<String> words = new ArrayList<String>();

Code Example 5

import java.util.List; //list abstract class
import java.util.ArrayList; //arraylist class

//Object Lists
List l = new ArrayList();
ArrayList a = new ArrayList();

//Specialized List
List<String> l = new ArrayList<String>();
ArrayList<Integer> a = new ArrayList<Integer>();
//only reference data types allowed in brackets <>

//Initial Capacity
List<Double> l = new ArrayList<Double>(5);
//list will start with a capacity of 5
//saves allocation times

Code Example 6

import java.util.ArrayList;

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

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