hashtableset.java

一个基于PlaceLab的室内和室外的智能导航系统

package org.placelab.collections;

import java.util.Enumeration;
import java.util.Hashtable;

/**
 * This is a replacement for HashtableSet based off of a Hashtable
 * rather than a HashMap.
 */
public class HashtableSet {
    protected Hashtable backing;
    // the value for every key.  i can't put null as a value into a Hashtable
    // so i do this instead.
    private static final Object object = new Object();
    
    public HashtableSet() {
        backing = new Hashtable();
    }
    public HashtableSet(int initialCapacity) {
        backing = new Hashtable(initialCapacity);
    }
    public HashtableSet(HashtableSet old) {
        this(old.size());
        addAll(old);
    }
    
    public void addAll(HashtableSet other) {
        Enumeration e = other.elements();
        while(e.hasMoreElements()) {
            this.addElement(e.nextElement());
        }
    }
    
    public void removeAll(HashtableSet other) {
        Enumeration e = other.elements();
        while(e.hasMoreElements()) {
            this.removeElement(e.nextElement());
        }
    }
    
    public void clear() {
        backing.clear();
    }
    
    public boolean contains(Object o) {
        return backing.containsKey(o);
    }
    
    public boolean isEmpty() {
        return backing.isEmpty();
    }
    
    public int size() {
        return backing.size();
    }
    
    public void addElement(Object o) {
        backing.put(o, object);
    }
    
    public Enumeration elements() {
        return backing.keys();
    }
    
    public void removeElement(Object o) {
        backing.remove(o);
    }
    
}