Unit 7

Many methods which can used with arrayLists size(); Returns the number of elements in the list add(obj); Adds element at the end add(index, object); Adds element at specific index remove(index); Removes element from specific index set(index, object);

Example: In dodgeball, the number of people in the game is changing based on who comes in or gets out

Primitive Data Types:

boolean char double int Wrapper Class Data Types (Store the primitive values as objects)

Boolean Character Double Integer

import java.util.ArrayList; //you must import the java.util package

public class introArrayList { public static void main (String[] args) { ArrayList e1 = new ArrayList(); //empty ArrayList e2 = new ArrayList(5); //5 elements ArrayList e3 = new ArrayList(); //you can store whatever objects you want } }</p>

When looking at int values, the == operator should be used. When searching for a double value, we need to make sure the value is close enough by doing some math. Object instances should always use the .equals(otherThing) method to check for a match.

</div> </div> </div>

// sum of the elements in the arraylist

ArrayList<Integer> num = new ArrayList<Integer>(); 

num.add(5);
num.add(1);
num.add(3);

int sum = 0;
for (int number : num) {
    sum += number;
}

System.out.println(sum)

9

</div>