ArrayLists allows for elements to be added and removed from an array after it is made. In a normal array, a new one has to be made every time

import java.util.ArrayList; // import the ArrayList class

ArrayList<String> Colors = new ArrayList<String>(); // Create an ArrayList object

add(int index, element) : adds an element to the list

Colors.add("red");
Colors.add("orange");
Colors.add("yellow");

true

addAll(int index, Collection collection) : adds all the elements in a list to another

ArrayList<String> shades = new ArrayList<String>(); 

shades.add("black");
shades.add("white");


Colors.addAll(shades);
System.out.println("colors: " + Colors + "\n");
System.out.println("shades: " + shades);

colors: [red, orange, yellow, black, white]

shades: [black, white]

size() : outputs the size of a list (number of elements)

System.out.println("The number of colors in Colors[] is currently " + Colors.size());

The number of colors in Colors[] is currently 5

clear() : clears everything in a list, reference list is stored

shades.clear();
System.out.println("shades: " + shades);

shades: []

remove(int index), removes the element from a list with that specific index, shifts the rest of the elements to the left and decreases their index by 1

Colors.remove(0);
System.out.println("colors: " + Colors);

colors: [orange, yellow, black, white]

remove(element) : remove the element with a specific name

Colors.add("green");

// removes orange item
Colors.remove("orange");
System.out.println("colors: " + Colors);

colors: [yellow, black, white, green]

get(int index) : obtains the element of that index

System.out.println("The first item listed is " + Colors.get(0));

The first item listed is yellow

set(int index, element) : replaces what is in that index with the new element

// replace the first term (index of 0)
Colors.set(0, "purple");
System.out.println("colors: " + Colors);

colors: [purple, black, white, green]

IndexOf(element) : returns the index of that element

System.out.println("The index for black is " + Colors.indexOf("black"));

The index for black is 1

lastIndexOf(element) : returns last occurrence of an object if not present in list

System.out.println("The index for yellow is " + Colors.lastIndexOf("yellow"));

The index for yellow is -1

equals(element) : true or false if two objects (lists) are equal to one another

if (Colors.equals(shades) == true) {
    System.out.println("all the colors are in shades");
}
else {
    System.out.println("the colors include non black/white shades");
}

the colors include non black/white shades

hashCode() : returns the hashcode of a list

System.out.println("The hashcode for this list is " + Colors.hashCode());

The hashcode for this list is -2139276674

isEmpty() : true or false if the list is empty (has no elements within)

System.out.println("Colors empty is " + shades.isEmpty());

Colors empty is true

contains(element) : returns true if the list contains the element

System.out.println("Colors contains blue is " + Colors.contains("blue"));

Colors contains blue is false

containsAll(Collection collection) : returns yes if the list contains all the elements of the other list

shades.add("pink");
shades.add("blue");

if (Colors.containsAll(shades) == true) {
    System.out.println("colors contains all shades");
}
else {
    System.out.println("colors does not contain all shades");
}

colors does not contain all shades

sort(Comparator comp) : sorts elements

Collections.sort(Colors);
System.out.println("Sorted colors " + Colors);

Sorted colors [black, green, purple, white]