Simple MVC based binding mechanism for android controls.

Change-Id: I80fe18e0e15f8a840d558de9863650505bd5fb00

1 files changed, 74 insertions, 0 deletions

diff --git a/core/java/android/util/ValueModel.java b/core/java/android/util/ValueModel.java
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+++ b/core/java/android/util/ValueModel.java
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+/*
+ * 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);
+}
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