CODEWITHSUNDEEP
java
FreddyReverend
FreddyReverend

Reputation: 9

Array List Index 0 size 0 error

I'm making a program of the Card game War and I need the cards to not reappear so I used an Array list. I'm having trouble with this array list as it's supposed to be random and remove the number, but I get the error IndexOutOfBoundsException: Index 0, Size 0 

List<Integer> values = new ArrayList<Integer>();
Random random = new Random();

Integer rand = random.nextInt(values.size()+1); 
Integer cardId = values.get(rand);
values.remove(rand);

Upvotes: 0

Views: 2609

Answers (5)

Paul Samsotha
Paul Samsotha

Reputation: 208974

You need to first give the List values before you can get values

List<Integer> values = new ArrayList<Integer>();
Random random = new Random();

Integer rand = random.nextInt(values.size()+1);

Try this to put values

for (int i = 1; i <= 52; i++){
    values.add(i);
}

Integer rand = random.nextInt(values.size() + 1);

Upvotes: 0

Elliott Frisch
Elliott Frisch

Reputation: 201439

First add your Card(s) to your values List (e.g. probably not Integer). What I'm saying is this, you need a deck of cards before you can play.

Upvotes: 3

Jason C
Jason C

Reputation: 40315

You get this error because you try to access index 0 of an empty array, as it says. You cannot do this.

Your code has multiple issues.

  • You are not actually storing anything in values.

  • The acceptable range of indexes for .get() is 0 to size-1. The return range of random.nextInt(size+1) is 0 to size. This can produce out of range index values. Array indexes start at 0.

Upvotes: 2

iWumbo
iWumbo

Reputation: 135

Provide the code for the values in the array...Or add values in the array.

Upvotes: 0

Jeroen Vannevel
Jeroen Vannevel

Reputation: 44439

Your list is empty and you're

1) Trying to retrieve a value

2) Trying to remove a value

Which throws an error because the list is empty.

Sidenote: you can define rand and cardId as int, instead of Integer. Autoboxing/unboxing will take care of that for you.

Add values to your list and it will work as expected (and if you change random.nextInt(values.size()+1) to random.nextInt(values.size())).

Upvotes: 2

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