ListIterator last hasNext () something incomprehensible
Let's say I run this code, it shows me this: 1 10 2 10 3 10
public class Test1{
public static void main(String[] args) {
LinkedList<Integer> list = new LinkedList<Integer>();
list.add((1));
list.add((2));
list.add((3));
ListIterator<Integer> it = list.listIterator();
while(it.hasNext()){
it.next();
it.add((10));
}
for(Integer i : list){
System.out.println(i);
}
}
I do not understand why the latter hasNext()
is the case, even if we think that we should be at the end of the list (in my understanding). On element 3.
First, the iterator is at 1. hasNext()
return true
because the list has 2 after. So I go into a loop, it it.next()
returns 1 to me and sets the cursor to 2. When I add 10, it happens at the cursor location, so between 1 and 2. it it.next()
returns 2 to me and sets the cursor to 3. Then I add 10 between 2 and 3 But at the moment I don't have the next of 3, so why does it hasNext()
return true to add 12 to the last place in the list?
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The cursor is always between items. When you add an item via a list iterator, the item is added at the cursor position, and the cursor moves after the item you just inserted. This is also explained in the javadoc .
Think about the cursor position in such a way that:
1 2 3
^
hasNext? yes => call next (returns 1)
1 2 3
^
call add
1 10 2 3
^
hasNext? yes => call next (returns 2)
1 10 2 3
^
call add
1 10 2 10 3
^
hasNext? yes => call next (returns 3)
1 10 2 10 3
^
call add
1 10 2 10 3 10
^
hasNext? no => exit loop
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