"Iterator.next()" methods should throw "NoSuchElementException"

By contract, any implementation of the java.util.Iterator.next() method should throw a NoSuchElementException exception when the iteration has no more elements. Any other behavior when the iteration is done could lead to unexpected behavior for users of this Iterator.

Noncompliant Code Example

public class MyIterator implements Iterator<String>{
  ...
  public String next(){
    if(!hasNext()){
      return null;
    }
    ...
  }
}

Compliant Solution

public class MyIterator implements Iterator<String>{
  ...
  public String next(){
    if(!hasNext()){
      throw new NoSuchElementException();
    }
    ...
  }
}