ArraySet Example

package example.set;
 
import java.io.Serializable;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
 
public class ArraySet extends AbstractSet implements Cloneable, Serializable {
 
    private ArrayList list;
 
    public ArraySet() {
	list = new ArrayList();
    }
 
    public ArraySet(Collection col) {
	list = new ArrayList();
 
	// No need to check for dups if col is a set
	Iterator itor = col.iterator();
	if (col instanceof Set) {
	    while (itor.hasNext()) {
		list.add(itor.next());
	    }
	} else {
	    while (itor.hasNext()) {
		add(itor.next());
	    }
	}
    }
 
    public Iterator iterator() {
	return list.iterator();
    }
 
    public int size() {
	return list.size();
    }
 
    public boolean add(Object element) {
	boolean modified;
	if (modified = !list.contains(element)) {
	    list.add(element);
	}
	return modified;
    }
 
    public boolean remove(Object element) {
	return list.remove(element);
    }
 
    public boolean isEmpty() {
	return list.isEmpty();
    }
 
    public boolean contains(Object element) {
	return list.contains(element);
    }
 
    public void clear() {
	list.clear();
    }
 
    public Object clone() {
	try {
	    ArraySet newSet = (ArraySet) super.clone();
	    newSet.list = (ArrayList) list.clone();
	    return newSet;
	} catch (CloneNotSupportedException e) {
	    throw new InternalError();
	}
    }
}