how hasnext() works in collection in java

Question

program:

public class SortedSet1 {

  public static void main(String[] args) {  

    List ac= new ArrayList();

    c.add(ac);
    ac.add(0,\"hai\");
    ac.add         


        

Answer 1

Your loop above iterates through the list using an index. it.hasNext() returns true until it reaches the end of the list. Since you don't call it.next() within your loop to advance the iterator, it.hasNext() keeps returning true, and your loop rolls on. Until, that is, k gets to be 5, at which point an IndexOutOfBoundsException is thrown, which exits the loop.

The proper idiom using an iterator would be

while(it.hasNext()){
    System.out.println(it.next());
}

or using an index

for(int k=0; k

However since Java5, the preferred way is using the foreach loop (and generics):

List ac= new ArrayList();
...
for(String elem : ac){
    System.out.println(elem);
}