1 /*
2  * Copyright (C) 2006 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  */
16 
17 package android.os;
18 
19 /**
20  * Interface for classes whose instances can be written to
21  * and restored from a {@link Parcel}.  Classes implementing the Parcelable
22  * interface must also have a non-null static field called <code>CREATOR</code>
23  * of a type that implements the {@link Parcelable.Creator} interface.
24  *
25  * <p>A typical implementation of Parcelable is:</p>
26  *
27  * <pre>
28  * public class MyParcelable implements Parcelable {
29  *     private int mData;
30  *
31  *     public int describeContents() {
32  *         return 0;
33  *     }
34  *
35  *     public void writeToParcel(Parcel out, int flags) {
36  *         out.writeInt(mData);
37  *     }
38  *
39  *     public static final Parcelable.Creator&lt;MyParcelable&gt; CREATOR
40  *             = new Parcelable.Creator&lt;MyParcelable&gt;() {
41  *         public MyParcelable createFromParcel(Parcel in) {
42  *             return new MyParcelable(in);
43  *         }
44  *
45  *         public MyParcelable[] newArray(int size) {
46  *             return new MyParcelable[size];
47  *         }
48  *     };
49  *
50  *     private MyParcelable(Parcel in) {
51  *         mData = in.readInt();
52  *     }
53  * }</pre>
54  */
55 public interface Parcelable {
56     /**
57      * Flag for use with {@link #writeToParcel}: the object being written
58      * is a return value, that is the result of a function such as
59      * "<code>Parcelable someFunction()</code>",
60      * "<code>void someFunction(out Parcelable)</code>", or
61      * "<code>void someFunction(inout Parcelable)</code>".  Some implementations
62      * may want to release resources at this point.
63      */
64     public static final int PARCELABLE_WRITE_RETURN_VALUE = 0x0001;
65 
66     /**
67      * Bit masks for use with {@link #describeContents}: each bit represents a
68      * kind of object considered to have potential special significance when
69      * marshalled.
70      */
71     public static final int CONTENTS_FILE_DESCRIPTOR = 0x0001;
72 
73     /**
74      * Describe the kinds of special objects contained in this Parcelable's
75      * marshalled representation.
76      *
77      * @return a bitmask indicating the set of special object types marshalled
78      * by the Parcelable.
79      */
describeContents()80     public int describeContents();
81 
82     /**
83      * Flatten this object in to a Parcel.
84      *
85      * @param dest The Parcel in which the object should be written.
86      * @param flags Additional flags about how the object should be written.
87      * May be 0 or {@link #PARCELABLE_WRITE_RETURN_VALUE}.
88      */
writeToParcel(Parcel dest, int flags)89     public void writeToParcel(Parcel dest, int flags);
90 
91     /**
92      * Interface that must be implemented and provided as a public CREATOR
93      * field that generates instances of your Parcelable class from a Parcel.
94      */
95     public interface Creator<T> {
96         /**
97          * Create a new instance of the Parcelable class, instantiating it
98          * from the given Parcel whose data had previously been written by
99          * {@link Parcelable#writeToParcel Parcelable.writeToParcel()}.
100          *
101          * @param source The Parcel to read the object's data from.
102          * @return Returns a new instance of the Parcelable class.
103          */
createFromParcel(Parcel source)104         public T createFromParcel(Parcel source);
105 
106         /**
107          * Create a new array of the Parcelable class.
108          *
109          * @param size Size of the array.
110          * @return Returns an array of the Parcelable class, with every entry
111          * initialized to null.
112          */
newArray(int size)113         public T[] newArray(int size);
114     }
115 
116     /**
117      * Specialization of {@link Creator} that allows you to receive the
118      * ClassLoader the object is being created in.
119      */
120     public interface ClassLoaderCreator<T> extends Creator<T> {
121         /**
122          * Create a new instance of the Parcelable class, instantiating it
123          * from the given Parcel whose data had previously been written by
124          * {@link Parcelable#writeToParcel Parcelable.writeToParcel()} and
125          * using the given ClassLoader.
126          *
127          * @param source The Parcel to read the object's data from.
128          * @param loader The ClassLoader that this object is being created in.
129          * @return Returns a new instance of the Parcelable class.
130          */
createFromParcel(Parcel source, ClassLoader loader)131         public T createFromParcel(Parcel source, ClassLoader loader);
132     }
133 }
134