arraylists.md

ArrayLists

ArrayLists are a more flexible and advanced version of Arrays.
Unlike arrays they need to be explicitly imported from java.utils.

import java.util.ArrayList;

There are several different ways to declare and initialize them.

ArrayList<String> list0; // declares without initializing
list0.add("LOL!"); // => throws not initialized
ArrayList<String> list1 = new ArrayList(); // initializes a new empty arraylist
ArrayList<String> list2 = new ArrayList(10); // sets initial capacity of 10
ArrayList<String> list3 = new ArrayList<>(); // same as list1 but with generics... idk.
ArrayList<String> list4 = new ArrayList<String>(); // more generics?!12 still dont know.
ArrayList<String> list5 = new ArrayList(list3);
ArrayList<String> list6 = list3;

We can declare ArrayLists without typing their content as well. They will accept anything they can handle as Object type if we do.

ArrayList abc = new ArrayList();
abc.add("lol");
abc.add(3);       // <- handled as Integer

Methods

Even though many of the methods for ArrayList have very similar functionality as the methods provided for arrays they don't all have the same names!

add()

Takes a value of the required type and adds it to the end of the list.

:::info This changes the amount of values in our data structure, which is NOT possible with arrays. :::