# EntityPropertyInstance.java

    /*
     * Copyright (c) 2007, Rickard Öberg. All Rights Reserved.
     * Copyright (c) 2008, Edward Yakop. All Rights Reserved.
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     *
     */
    package org.qi4j.runtime.entity;

    import org.qi4j.runtime.property.PropertyInfo;
    import org.qi4j.runtime.property.PropertyInstance;
    import org.qi4j.spi.entity.EntityState;

    /**
     * {@code EntityPropertyInstance} represents a property whose value must be backed by an EntityState.
     */
    public class EntityPropertyInstance<T>
        extends PropertyInstance<T>
    {
        private final EntityState entityState;

        /**
         * Construct an instance of {@code PropertyInstance} with the specified arguments.
         *
         * @param aPropertyInfo The property info. This argument must not be {@code null}.
         * @param entityState EntityState
         */
        @SuppressWarnings( "unchecked" )
        public EntityPropertyInstance( PropertyInfo aPropertyInfo, EntityState entityState )
        {
            super( aPropertyInfo, (T) entityState.propertyValueOf( aPropertyInfo.qualifiedName() ) );
            this.entityState = entityState;
        }

        /**
         * Sets this property value.
         *
         * @param aNewValue The new value.
         */
        @Override
        public void set( T aNewValue )
        {
            super.set( aNewValue );
            entityState.setPropertyValue( model.qualifiedName(), aNewValue );
        }
    }