public abstract class Dictionary<K,D> implements Map<K,D> {

  public abstract void insert(K k, D d); 
  public abstract void delete(K k); 
  public abstract D find(K k);
  public abstract boolean iselement(K k);
  public abstract Iterator<K,D> iterator();

  public boolean isempty() {
    return size()==0;
  }

  public int size() {
    Iterator<K,D> it;
    int size = 0;
    for(it=iterator(); it.more(); it.step()) size++;
    return size;
  }

  public SimpleIterator<K> simpleiterator() {
    return new SimpleIterator(iterator());
  }

  public Array<K> array() {
    int i;
    Array<K> a = new Array<K>();
    SimpleIterator<K> it;
    for(i=0, it=simpleiterator(); it.more(); i++, it.step()) 
      a.set(i, it.key());
    return a;
  }

  public void print() {
    Iterator<K,D> i;
    for(i=iterator(); i.more(); i.step())
    	System.out.println(i.key()+" : "+i.data());
  }

  public String sanity() {
    Iterator<K,D> i;
    int s=0;
    String t = "";
    for(i=iterator(); i.more(); i.step()) {
      s++;
      if(!iselement(i.key())) t += ""+i.key()+" not iselement() ";
      if(i.data()==null) t += "i.data()==null for i.key()="+i.key();
      if(!i.data().equals(find(i.key()))) t += "i.data() != find(i.key())";
      if(!t.equals("")) return t;
    }
    if(s!=size()) return "size mismatch: "+s+" vs. "+size();
    return "";
  }
}