2 7 - 2 Arraylists Methods

Given this:

import java.util.ArrayList;
 
ArrayList<E> array = new ArrayList<E>();

boolean add(E obj) Summary: Appends obj to the end of list Example: arrayList.add(“ADD!”);

void add(int index, E obj)
Summary: Inserts obj at position index, moves elements index and higher up, adds 1 to size. Example : arrayList.add(2, “Add”)

E.get(int index) Summary: returns element at the position index

int size() summary: returns number of elements in list example: int num = arrayList.size()

E.set(int index, E obj) summary: Replaces element at index with obj, returns replaced element. arrayList.set(2,“New Val”);

E.remove(int, index) Summary: Removes element from position index. Subtracts 1 from size and moves elements index and higher down one index. Example: arrayList.remove(2);

ArrayList list = new ArrayList(); list.add(5); list.add(3); list.add(10); list.add(5);

0	1	2	3
5	3	10	5

list.add(2,15);

| 0 | 1 | 2 | 3 | 4 | | --- | --- | --- | --- | | 5 | 3 | 15 | 10 | 5 |

int val = list.get(1); System.out.println(val); // prints 3

System.out.println(list.size()); // prints 4 list.add(2,15); System.out.println(list.size()); // prints 5

size is always 1 greater than the highest index value

0	1	2	3
5	3	10	5

int val = list.set(2,34)

System.out.println(val); returns 10

0	1	2	3
5	3	34	5

int val = list.remove(2) System.out.println(val); // returns 34

0	1	2
5	3	4

3	10
0	1