ObservableField.java revision 9784c9aaedeb863018f5fcaa0a598e8e2f8ed2f3 
1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package android.databinding;
17
18import java.io.Serializable;
19
20/**
21 * An object wrapper to make it observable.
22 * <p>
23 * Observable field classes may be used instead of creating an Observable object:
24 * <pre><code>public class MyDataObject {
25 *     public final ObservableField&lt;String> name = new ObservableField&lt;String>();
26 *     public final ObservableInt age = new ObservableInt();
27 * }</code></pre>
28 * Fields of this type should be declared final because bindings only detect changes in the
29 * field's value, not of the field itself.
30 *
31 * @param <T> The type parameter for the actual object.
32 * @see android.databinding.ObservableParcelable
33 */
34public class ObservableField<T> extends BaseObservable implements Serializable {
35    static final long serialVersionUID = 1L;
36    private T mValue;
37
38    /**
39     * Wraps the given object and creates an observable object
40     *
41     * @param value The value to be wrapped as an observable.
42     */
43    public ObservableField(T value) {
44        mValue = value;
45    }
46
47    /**
48     * Creates an empty observable object
49     */
50    public ObservableField() {
51    }
52
53    /**
54     * @return the stored value.
55     */
56    public T get() {
57        return mValue;
58    }
59
60    /**
61     * Set the stored value.
62     */
63    public void set(T value) {
64        if (value != mValue) {
65            mValue = value;
66            notifyChange();
67        }
68    }
69}
70