How do I set up CollapsableHashtable to take parameters?

[code]
/*
 * CollapsableHashtable.java
 *
 * Created on March 20, 2007, 11:17 AM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package com.ppowell.tools.CollectionTools;

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

/**
 * Allows for "removeAll" of all elements within {@link
java.util.Hashtable}
 * @author Phil Powell
 * @version JDK 1.6.0
 */
public class CollapsableHashtable<K, V> extends Hashtable<K, V> {

    /** Creates a new instance of CollapsableHashtable */
    public CollapsableHashtable() {
        super();
    }

    /** Remove all {@link java.lang.Object} keys from {@link
java.util.Hashtable} */
    public void removeAll() {
        while (!isEmpty()) {
           Enumeration keys = this.keys();
           while (keys.hasMoreElements()) {
               remove(keys.nextElement());
           }
        }
    }
}

[/code]

Sorry folks, I'm so not good at this. How do I ensure that my
CollapsableHashtable class will fully extend Hashtable<K, V> inasmuch
as it will take identifier parameters just like Hashtable<K, V>?

When I try this:

[code]
 private Hashtable<String, CollapsableHashtable<String, String>>
phraseHash;
[/code]

I wind up with this compiler error:

[code]
C:\Documents and Settings\me\classes\GUI\src\com\ppowell\applications
\games\RockPaperScissors.java:43: type
com.ppowell.tools.CollectionTools.CollapsableHashtable does not take
parameters
    private Hashtable<String, CollapsableHashtable<String, String>>
phraseHash;
[/code]

So what must I do within CollapsableHashtable to ensure that it can
take parameters?

Thanx
Phil