src/de/j32/util/FilteredIterator.java

   1 package de.j32.util;
   2
   3 import java.util.Iterator;
   4 import java.util.NoSuchElementException;
   5
   6 public class FilteredIterator<E> implements Iterator<E>
   7 {
   8     Iterator<E> base_;
   9     Filter<E> filter_;
  10     E next_;
  11     boolean hasNext_ = true;
  12
  13     public FilteredIterator(Iterator<E> base, Filter<E> filter)
  14     {
  15         base_ = base;
  16         filter_ = filter;
  17         advance();
  18     }
  19
  20     public E next()
  21     {
  22         if (hasNext_) {
  23             E rv = next_;
  24             advance();
  25             return rv;
  26         }
  27         else throw new NoSuchElementException();
  28     }
  29
  30     public boolean hasNext()
  31     {
  32         return hasNext_;
  33     }
  34
  35     public void remove()
  36     {
  37         throw new UnsupportedOperationException();
  38     }
  39
  40     void advance()
  41     {
  42         while (base_.hasNext()) {
  43             next_ = base_.next();
  44             if (filter_.match(next_)) return;
  45         }
  46         hasNext_ = false;
  47         next_ = null;
  48     }
  49
  50 }