1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5  * in compliance with the License. You may obtain a copy of the License at
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the License
10  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11  * or implied. See the License for the specific language governing permissions and limitations under
12  * the License.
13  */
14 package androidx.leanback.widget;
15 
16 import java.util.ArrayList;
17 import java.util.HashMap;
18 
19 /**
20  * A ClassPresenterSelector selects a {@link Presenter} based on the item's
21  * Java class.
22  */
23 public final class ClassPresenterSelector extends PresenterSelector {
24 
25     private final ArrayList<Presenter> mPresenters = new ArrayList<Presenter>();
26 
27     private final HashMap<Class<?>, Object> mClassMap = new HashMap<Class<?>, Object>();
28 
29     /**
30      * Sets a presenter to be used for the given class.
31      * @param cls The data model class to be rendered.
32      * @param presenter The presenter that renders the objects of the given class.
33      * @return This ClassPresenterSelector object.
34      */
addClassPresenter(Class<?> cls, Presenter presenter)35     public ClassPresenterSelector addClassPresenter(Class<?> cls, Presenter presenter) {
36         mClassMap.put(cls, presenter);
37         if (!mPresenters.contains(presenter)) {
38             mPresenters.add(presenter);
39         }
40         return this;
41     }
42 
43     /**
44      * Sets a presenter selector to be used for the given class.
45      * @param cls The data model class to be rendered.
46      * @param presenterSelector The presenter selector that finds the right presenter for a given
47      *                          class.
48      * @return This ClassPresenterSelector object.
49      */
addClassPresenterSelector(Class<?> cls, PresenterSelector presenterSelector)50     public ClassPresenterSelector addClassPresenterSelector(Class<?> cls,
51             PresenterSelector presenterSelector) {
52         mClassMap.put(cls, presenterSelector);
53         Presenter[] innerPresenters = presenterSelector.getPresenters();
54         for (int i = 0; i < innerPresenters.length; i++)
55         if (!mPresenters.contains(innerPresenters[i])) {
56             mPresenters.add(innerPresenters[i]);
57         }
58         return this;
59     }
60 
61     @Override
getPresenter(Object item)62     public Presenter getPresenter(Object item) {
63         Class<?> cls = item.getClass();
64         Object presenter = null;
65 
66         do {
67             presenter = mClassMap.get(cls);
68             if (presenter instanceof PresenterSelector) {
69                 Presenter innerPresenter = ((PresenterSelector) presenter).getPresenter(item);
70                 if (innerPresenter != null) {
71                     return innerPresenter;
72                 }
73             }
74             cls = cls.getSuperclass();
75         } while (presenter == null && cls != null);
76 
77         return (Presenter) presenter;
78     }
79 
80     @Override
getPresenters()81     public Presenter[] getPresenters() {
82         return mPresenters.toArray(new Presenter[mPresenters.size()]);
83     }
84 }
85