rspec/rules/S1849/java/rule.adoc

== Why is this an issue?

Calling ``++Iterator.hasNext()++`` is not supposed to have any side effects, and therefore should not change the state of the iterator. ``++Iterator.next()++`` advances the iterator by one item. So calling it inside ``++Iterator.hasNext()++``, breaks the ``++hasNext()++`` contract, and will lead to unexpected behavior in production.


=== Noncompliant code example

[source,java]
----
public class FibonacciIterator implements Iterator<Integer>{
...
@Override
public boolean hasNext() {
  if(next() != null) {
    return true;
  }
  return false;
}
...
}
----


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Refactor the implementation of this "Iterator.hasNext()" method to not call "Iterator.next()".


'''
== Comments And Links
(visible only on this page)

=== is duplicated by: S2113

endif::env-github,rspecator-view[]