| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * 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 android.util; |
| |
| /** |
| * A ValueModel is an abstraction for a 'slot' or place in memory in which a value |
| * may be stored and retrieved. A common implementation of ValueModel is a regular property of |
| * an object, whose value may be retrieved by calling the appropriate <em>getter</em> |
| * method and set by calling the corresponding <em>setter</em> method. |
| * |
| * @param <T> the value type |
| * |
| * @see PropertyValueModel |
| */ |
| public abstract class ValueModel<T> { |
| /** |
| * The empty model should be used in place of {@code null} to indicate that a |
| * model has not been set. The empty model has no value and does nothing when it is set. |
| */ |
| public static final ValueModel EMPTY = new ValueModel() { |
| @Override |
| public Class getType() { |
| return Object.class; |
| } |
| |
| @Override |
| public Object get() { |
| return null; |
| } |
| |
| @Override |
| public void set(Object value) { |
| |
| } |
| }; |
| |
| protected ValueModel() { |
| } |
| |
| /** |
| * Returns the type of this property. |
| * |
| * @return the property type |
| */ |
| public abstract Class<T> getType(); |
| |
| /** |
| * Returns the value of this property. |
| * |
| * @return the property value |
| */ |
| public abstract T get(); |
| |
| /** |
| * Sets the value of this property. |
| * |
| * @param value the new value for this property |
| */ |
| public abstract void set(T value); |
| } |