abstracthashedmap.java

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            parent.clear( );
        }

        public boolean contains(Object value)
        {
            return parent.containsValue( value );
        }

        public Iterator iterator()
        {
            return parent.createValuesIterator( );
        }
    }

    /**
     * Values iterator.
     */
    protected static class ValuesIterator extends HashIterator
    {

        protected ValuesIterator(AbstractHashedMap parent)
        {
            super( parent );
        }

        public Object next()
        {
            return super.nextEntry( ).getValue( );
        }
    }

    // -----------------------------------------------------------------------
    /**
     * HashEntry used to store the data.
     * <p>
     * If you subclass <code>AbstractHashedMap</code> but not
     * <code>HashEntry</code> then you will not be able to access the
     * protected fields. The <code>entryXxx()</code> methods on
     * <code>AbstractHashedMap</code> exist to provide the necessary access.
     */
    protected static class HashEntry
        implements
        Map.Entry
    {
        /** The next entry in the hash chain */
        protected HashEntry next;
        /** The hash code of the key */
        protected int hashCode;
        /** The key */
        protected Object key;
        /** The value */
        protected Object value;

        protected HashEntry(HashEntry next,
                            int hashCode,
                            Object key,
                            Object value)
        {
            super( );
            this.next = next;
            this.hashCode = hashCode;
            this.key = key;
            this.value = value;
        }

        public Object getKey()
        {
            return (key == NULL ? null : key);
        }

        public Object getValue()
        {
            return value;
        }

        public Object setValue(Object value)
        {
            Object old = this.value;
            this.value = value;
            return old;
        }

        public boolean equals(Object obj)
        {
            if ( obj == this )
            {
                return true;
            }
            if ( obj instanceof Map.Entry == false )
            {
                return false;
            }
            Map.Entry other = (Map.Entry) obj;
            return (getKey( ) == null ? other.getKey( ) == null : getKey( ).equals( other.getKey( ) )) && (getValue( ) == null ? other.getValue( ) == null : getValue( ).equals( other.getValue( ) ));
        }

        public int hashCode()
        {
            return (getKey( ) == null ? 0 : getKey( ).hashCode( )) ^ (getValue( ) == null ? 0 : getValue( ).hashCode( ));
        }

        public String toString()
        {
            return new StringBuffer( ).append( getKey( ) ).append( '=' ).append( getValue( ) ).toString( );
        }
    }

    /**
     * Base Iterator
     */
    protected static abstract class HashIterator
        implements
        Iterator
    {

        /** The parent map */
        protected final AbstractHashedMap parent;
        /** The current index into the array of buckets */
        protected int hashIndex;
        /** The last returned entry */
        protected HashEntry last;
        /** The next entry */
        protected HashEntry next;
        /** The modification count expected */
        protected int expectedModCount;

        protected HashIterator(AbstractHashedMap parent)
        {
            super( );
            this.parent = parent;
            HashEntry[] data = parent.data;
            int i = data.length;
            HashEntry next = null;
            while ( i > 0 && next == null )
            {
                next = data[--i];
            }
            this.next = next;
            this.hashIndex = i;
            this.expectedModCount = parent.modCount;
        }

        public boolean hasNext()
        {
            return (next != null);
        }

        protected HashEntry nextEntry()
        {
            if ( parent.modCount != expectedModCount )
            {
                throw new ConcurrentModificationException( );
            }
            HashEntry newCurrent = next;
            if ( newCurrent == null )
            {
                throw new NoSuchElementException( AbstractHashedMap.NO_NEXT_ENTRY );
            }
            HashEntry[] data = parent.data;
            int i = hashIndex;
            HashEntry n = newCurrent.next;
            while ( n == null && i > 0 )
            {
                n = data[--i];
            }
            next = n;
            hashIndex = i;
            last = newCurrent;
            return newCurrent;
        }

        protected HashEntry currentEntry()
        {
            return last;
        }

        public void remove()
        {
            if ( last == null )
            {
                throw new IllegalStateException( AbstractHashedMap.REMOVE_INVALID );
            }
            if ( parent.modCount != expectedModCount )
            {
                throw new ConcurrentModificationException( );
            }
            parent.remove( last.getKey( ) );
            last = null;
            expectedModCount = parent.modCount;
        }

        public String toString()
        {
            if ( last != null )
            {
                return "Iterator[" + last.getKey( ) + "=" + last.getValue( ) + "]";
            }
            else
            {
                return "Iterator[]";
            }
        }
    }

    // -----------------------------------------------------------------------
    /**
     * Writes the map data to the stream. This method must be overridden if a
     * subclass must be setup before <code>put()</code> is used.
     * <p>
     * Serialization is not one of the JDK's nicest topics. Normal serialization
     * will initialise the superclass before the subclass. Sometimes however,
     * this isn't what you want, as in this case the <code>put()</code> method
     * on read can be affected by subclass state.
     * <p>
     * The solution adopted here is to serialize the state data of this class in
     * this protected method. This method must be called by the
     * <code>writeObject()</code> of the first serializable subclass.
     * <p>
     * Subclasses may override if they have a specific field that must be
     * present on read before this implementation will work. Generally, the read
     * determines what must be serialized here, if anything.
     *
     * @param out
     *            the output stream
     */
    protected void doWriteObject(ObjectOutputStream out) throws IOException
    {
        out.writeFloat( loadFactor );
        out.writeInt( data.length );
        out.writeInt( size );
        for ( MapIterator it = mapIterator( ); it.hasNext( ); )
        {
            out.writeObject( it.next( ) );
            out.writeObject( it.getValue( ) );
        }
    }

    /**
     * Reads the map data from the stream. This method must be overridden if a
     * subclass must be setup before <code>put()</code> is used.
     * <p>
     * Serialization is not one of the JDK's nicest topics. Normal serialization
     * will initialise the superclass before the subclass. Sometimes however,
     * this isn't what you want, as in this case the <code>put()</code> method
     * on read can be affected by subclass state.
     * <p>
     * The solution adopted here is to deserialize the state data of this class
     * in this protected method. This method must be called by the
     * <code>readObject()</code> of the first serializable subclass.
     * <p>
     * Subclasses may override if the subclass has a specific field that must be
     * present before <code>put()</code> or <code>calculateThreshold()</code>
     * will work correctly.
     *
     * @param in
     *            the input stream
     */
    protected void doReadObject(ObjectInputStream in) throws IOException,
                                                     ClassNotFoundException
    {
        loadFactor = in.readFloat( );
        int capacity = in.readInt( );
        int size = in.readInt( );
        init( );
        data = new HashEntry[capacity];
        for ( int i = 0; i < size; i++ )
        {
            Object key = in.readObject( );
            Object value = in.readObject( );
            put( key,
                 value );
        }
        threshold = calculateThreshold( data.length,
                                        loadFactor );
    }

    // -----------------------------------------------------------------------
    /**
     * Clones the map without cloning the keys or values.
     * <p>
     * To implement <code>clone()</code>, a subclass must implement the
     * <code>Cloneable</code> interface and make this method public.
     *
     * @return a shallow clone
     */
    protected Object clone()
    {
        try
        {
            AbstractHashedMap cloned = (AbstractHashedMap) super.clone( );
            cloned.data = new HashEntry[data.length];
            cloned.entrySet = null;
            cloned.keySet = null;
            cloned.values = null;
            cloned.modCount = 0;
            cloned.size = 0;
            cloned.init( );
            cloned.putAll( this );
            return cloned;

        }
        catch ( CloneNotSupportedException ex )
        {
            return null; // should never happen
        }
    }

    /**
     * Compares this map with another.
     *
     * @param obj
     *            the object to compare to
     * @return true if equal
     */
    public boolean equals(Object obj)
    {
        if ( obj == this )
        {
            return true;
        }
        if ( obj instanceof Map == false )
        {
            return false;
        }
        Map map = (Map) obj;
        if ( map.size( ) != size( ) )
        {
            return false;
        }
        MapIterator it = mapIterator( );
        try
        {
            while ( it.hasNext( ) )
            {
                Object key = it.next( );
                Object value = it.getValue( );
                if ( value == null )
                {
                    if ( map.get( key ) != null || map.containsKey( key ) == false )
                    {
                        return false;
                    }
                }
                else
                {
                    if ( value.equals( map.get( key ) ) == false )
                    {
                        return false;
                    }
                }
            }
        }
        catch ( ClassCastException ignored )
        {
            return false;
        }
        catch ( NullPointerException ignored )
        {
            return false;
        }
        return true;
    }

    /**
     * Gets the standard Map hashCode.
     *
     * @return the hash code defined in the Map interface
     */
    public int hashCode()
    {
        int total = 0;
        Iterator it = createEntrySetIterator( );
        while ( it.hasNext( ) )
        {
            total += it.next( ).hashCode( );
        }
        return total;
    }

    /**
     * Gets the map as a String.
     *
     * @return a string version of the map
     */
    public String toString()
    {
        if ( size( ) == 0 )
        {
            return "{}";
        }
        StringBuffer buf = new StringBuffer( 32 * size( ) );
        buf.append( '{' );

        MapIterator it = mapIterator( );
        boolean hasNext = it.hasNext( );
        while ( hasNext )
        {
            Object key = it.next( );
            Object value = it.getValue( );
            buf.append( key == this ? "(this Map)" : key ).append( '=' ).append( value == this ? "(this Map)" : value );

            hasNext = it.hasNext( );
            if ( hasNext )
            {
                buf.append( ',' ).append( ' ' );
            }
        }

        buf.append( '}' );
        return buf.toString( );
    }
}