Java tutorial
//package com.java2s; import java.util.Iterator; import java.util.NoSuchElementException; public class Main { public static <ELEMENT_TYPE> Iterator<ELEMENT_TYPE> unmodifiableEmptyIterator() { return new Iterator<ELEMENT_TYPE>() { @Override public boolean hasNext() { return false; } @Override public ELEMENT_TYPE next() { throw new NoSuchElementException(); } @Override public void remove() { throw new UnsupportedOperationException("This collection is imutable and empty"); } }; } }