Convert an array into an ArrayList

Question

I'm having a lot of trouble turning an array into an ArrayList in Java. This is my array right now:

Card[] hand = new Card[2];

"hand" holds an array of "Cards". How this would look like as an ArrayList?

Have you read any reference info, e.g. http://docs.oracle.com/javase/tutorial/collections/? — Oliver Charlesworth, Mar 21 '12 at 19:13

score 89 · Answer 1 · answered Mar 21 '12 at 19:13

89

This will give you a list.

List<Card> cardsList = Arrays.asList(hand);

If you want an arraylist, you can do

ArrayList<Card> cardsList = new ArrayList<Card>(Arrays.asList(hand));

answered Mar 21 '12 at 19:13

Kal

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Nope! This gives an object that acts as a `List` wrapper around an underlying object. Unlike a real `ArrayList`, the resulting `List` is not resizable, and attempts to `.add` elements to the end of it will result in `UnsupportedOperationException`. – Adam Norberg Mar 21 '12 at 19:14

score 39 · Accepted Answer · edited Nov 23 '13 at 08:54

39

As an ArrayList that line would be

import java.util.ArrayList;
...
ArrayList<Card> hand = new ArrayList<Card>();

To use the ArrayList you have do

hand.get(i); //gets the element at position i 
hand.add(obj); //adds the obj to the end of the list
hand.remove(i); //removes the element at position i
hand.add(i, obj); //adds the obj at the specified index
hand.set(i, obj); //overwrites the object at i with the new obj

Also read this http://docs.oracle.com/javase/6/docs/api/java/util/ArrayList.html

edited Nov 23 '13 at 08:54

Afshin Moazami

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answered Mar 21 '12 at 19:14

twain249

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Thank you! One last quick question.. how would I accept an arraylist into a method? Right now I have: public void getHandValue(ArrayList< Card > hand) {...} The arraylist is in my main args. Just the word "ArrayList" is coming up as an error. – Saatana Mar 21 '12 at 19:36
you should be able to have a method signature `void getHandValue(ArrayList hand)` the problem is more than likely when you are calling that method. – twain249 Mar 21 '12 at 20:29

score 15 · Answer 3 · answered Mar 21 '12 at 19:12

15

List<Card> list = new ArrayList<Card>(Arrays.asList(hand));

answered Mar 21 '12 at 19:12

Eng.Fouad

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score 1 · Answer 4 · answered Mar 21 '12 at 19:13

1

declaring the list (and initializing it with an empty arraylist)

List<Card> cardList = new ArrayList<Card>();

adding an element:

Card card;
cardList.add(card);

iterating over elements:

for(Card card : cardList){
    System.out.println(card);
}

answered Mar 21 '12 at 19:13

bpgergo

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Convert an array into an ArrayList

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