ArrayList

Arrays

Can hold any datatype (ex: primitives or objects) but have fixed size

ArrayList

Can only hold objects but you can change their size. Can get around the limitation of datatypes by using a wrapper class of whatever primitive data type you want to put (ex: Integer for int)

They're kind of like a wrapper around Java's arrays that make them easier to use

import java.util.Arrays;
import java.util.ArrayList; 

public class ArrayVArrayList { 

    public static void main(String[] args){

        //Declaring an Array
        // Also can do: String[] scrumArray = new String[4]; //initializes string array and must give size
                    // ^^ all 4 elements are null until they are set

        String[] scrumArray = {"Calissa", "Evan", "Kian", "Samuel"}; //initializes values right away, size is implied

        //Declaring an ArrayList
        // Also can do: ArrayList<String> scrumArrayList = new ArrayList<>(); //instantiate arraylist, must declare datatype, uses diamond (<>) operator  

        ArrayList<String> scrumArrayList = new ArrayList<>(Arrays.asList("Calissa", "Evan", "Kian", "Samuel")); //passes .asList method (values you want to have in your arrayList)

        //Getting value from Array
        System.out.println(scrumArray[1]);

        //Getting value from Array
        System.out.println(scrumArrayList.get(1));

        //Getting length from Array
        System.out.println(scrumArray.length); //field on array

        //Getting length from ArrayList
        System.out.println(scrumArrayList.size()); //size is method call

        //Adding element to end of ArrayList
        scrumArrayList.add("John"); //calls add method, pass element you want to add
        System.out.println(scrumArrayList.get(4));

        //Change element in Array
        scrumArray[1] = "Hassan";
        System.out.println(scrumArray[1]);

        //Change element in ArrayList
        scrumArrayList.set(1, "Hassan");
        System.out.println(scrumArrayList.get(1));

        //Remove element in ArrayList
        /*
         * Note: Can also do scrumArrayList.remove("ObjectName");
         */

        scrumArrayList.remove(1);
        System.out.println(scrumArrayList.get(1));

        //Print Array
        System.out.println(scrumArray); //gives memory address

        //^^In order to print array you have to do a for loop and iterate over all elements

        System.out.println(scrumArrayList); //implemented two string method so it prints out nicely


}

}

ArrayVArrayList.main(null);

Evan
Evan
4
4
John
Hassan
Hassan
Kian
[Ljava.lang.String;@438de3d0
[Calissa, Kian, Samuel, John]