Document

Create An Empty ArrayList

ArrayList()

Ready to store generic objects

ArrayList<E>()

Ready to store objects of specific class

Using ArrayList(), ArrayList<E>()

// ArrayList of plain objects
ArrayList someObjs = new ArrayList();

// ArrayList of SoccerPlayer instances
ArrayList<SoccerPlayer> allPlayers = 
new ArrayList<SoccerPlayer>();

Get Number Of ArrayList Elements

size()

Returns the number of elements in the ArrayList object. Useful for ArrayList traversal.

Using size()

    ArrayList<SoccerPlayer> allPlayers = 
      new ArrayList<SoccerPlayer>();
    allPlayers.add(player1);
    allPlayers.add(player2);
    allPlayers.add(player3);
    allPlayers.add(player4);
    allPlayers.add(player5);

    allPlayers.size() returns 5!

Add Element To An ArrayList

add(E obj), add (int index, E obj)

Adds element to end, or at index

add(E obj)

add (int index, E obj)

Using add(E obj), add(int index, E obj)

ArrayList<SoccerPlayer> allPlayers = 
new ArrayList<SoccerPlayer>();
                              
add(player) // Adds player to end of ArrayList
add(2, player) // Adds player at index 2, shifts other elements right.

Retrieve Element From ArrayList

E get(int index)

Gets the element at specified index of ArrayList

Using get(int index)

ArrayList<SoccerPlayer> allPlayers = 
new ArrayList<SoccerPlayer>();
allPlayers.add(player1);
allPlayers.add(player2);
allPlayers.add(player3);
allPlayers.add(player4);
allPlayers.add(player5);

allPlayers.get(3) returns player4!

Set Element In ArrayList

E set(int index, E obj)

Sets the element at specified index of ArrayList

Using set(int index, E obj)

ArrayList<SoccerPlayer> allPlayers = 
new ArrayList<SoccerPlayer>();
allPlayers.add(player1);
allPlayers.add(player2);
allPlayers.add(player3);

SoccerPlayer replacementPlayer = new SoccerPlayer();

allPlayers.set(1, replacementPlayer) 
Returns player2! replacementPlayer replaces player4.

Remove Element From ArrayList

E remove(int index)

Removes the element at specified index of ArrayList

Using remove(int index)

ArrayList<SoccerPlayer> allPlayers = 
new ArrayList<SoccerPlayer>();
allPlayers.add(player1);
allPlayers.add(player2);
allPlayers.add(player3);
allPlayers.add(player4);
allPlayers.add(player5);

allPlayers.remove(2) returns player3! 
Elements to right are shifted left.