ArrayList<Level> myLevel question

Programming Questions

dazzid

ArrayList<Level> myLevel question

in Programming Questions • 10 months ago

Hi all,

I don't know why this int val = it.nextIndex() is not working, it says "The function nextIndex does not exist." I don't have idea why. Can you help me?

void draw() {

background(50);

Iterator<Level> it = myLevel.iterator();

while (it.hasNext ()) {

int val = it.nextIndex();

Level oneLevel = it.next();

println(val);

//oneLevel.display(randomNumbers[it.nextIndex()-1]);

}

Replies(5)

GoToLoop

Re: ArrayList<Level> myLevel question

10 months ago

According to this official link -> http://docs.oracle.com/javase/6/docs/api/java/util/Iterator.html
There are only 3 methods to interface Iterator -> hasNext(), next() and remove().
And nextIndex() is not 1 of them!

Also, I have my doubts whether an int variable would be valid to store its returned value.

GoToLoop

Re: Re: ArrayList<Level> myLevel question

10 months ago

Searching further, if by chance, nextIndex() is a method from class Level; you have to use next() 1st:

int val = it .next() .nextIndex();

However if you want to keep using methods from that same instance, you can't use next() again; lest you end up addressing next instance prematurely!

So you would need to store a copy of that instance for those cases!

PhiLho

Re: ArrayList<Level> myLevel question

10 months ago

That's because you want a ListIterator:

Copy code

ArrayList<Level> myLevel = new ArrayList<Level>();
class Level {}
void setup() { myLevel.add(new Level()); }
void draw() {
background(50);
ListIterator<Level> it = myLevel.listIterator();
while (it.hasNext()) {
int val = it.nextIndex();
Level oneLevel = it.next();
println(val);
//oneLevel.display(randomNumbers[it.nextIndex()-1]);
}
}

GoToLoop

Re: Re: ArrayList<Level> myLevel question

10 months ago

Oops! Still newbie @ Java!
Forgot there are more specialized & powerful classes and interfaces like ListIterator -> http://docs.oracle.com/javase/6/docs/api/java/util/ListIterator.html

Never used them anyways!

dazzid

Re: Re: ArrayList<Level> myLevel question

10 months ago

Hey PhiLho

Thanx for your answer, that is exactly what I was searching for.

all the best

David

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