459 lines
14 KiB
Java
459 lines
14 KiB
Java
/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.os;
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import android.os.Bundle;
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import android.os.Parcel;
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import android.os.Parcelable;
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import android.util.TimeUtils;
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/**
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*
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* Defines a message containing a description and arbitrary data object that can be
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* sent to a {@link Handler}. This object contains two extra int fields and an
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* extra object field that allow you to not do allocations in many cases.
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*
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* <p class="note">While the constructor of Message is public, the best way to get
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* one of these is to call {@link #obtain Message.obtain()} or one of the
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* {@link Handler#obtainMessage Handler.obtainMessage()} methods, which will pull
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* them from a pool of recycled objects.</p>
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*/
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public final class Message implements Parcelable {
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/**
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* User-defined message code so that the recipient can identify
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* what this message is about. Each {@link Handler} has its own name-space
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* for message codes, so you do not need to worry about yours conflicting
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* with other handlers.
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*/
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public int what;
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/**
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* arg1 and arg2 are lower-cost alternatives to using
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* {@link #setData(Bundle) setData()} if you only need to store a
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* few integer values.
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*/
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public int arg1;
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/**
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* arg1 and arg2 are lower-cost alternatives to using
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* {@link #setData(Bundle) setData()} if you only need to store a
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* few integer values.
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*/
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public int arg2;
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/**
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* An arbitrary object to send to the recipient. When using
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* {@link Messenger} to send the message across processes this can only
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* be non-null if it contains a Parcelable of a framework class (not one
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* implemented by the application). For other data transfer use
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* {@link #setData}.
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*
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* <p>Note that Parcelable objects here are not supported prior to
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* the {@link android.os.Build.VERSION_CODES#FROYO} release.
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*/
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public Object obj;
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/**
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* Optional Messenger where replies to this message can be sent. The
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* semantics of exactly how this is used are up to the sender and
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* receiver.
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*/
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public Messenger replyTo;
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/*package*/ long when;
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/*package*/ Bundle data;
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/*package*/ Handler target;
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/*package*/ Runnable callback;
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// sometimes we store linked lists of these things
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/*package*/ Message next;
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private static Object mPoolSync = new Object();
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private static Message mPool;
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private static int mPoolSize = 0;
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private static final int MAX_POOL_SIZE = 10;
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/**
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* Return a new Message instance from the global pool. Allows us to
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* avoid allocating new objects in many cases.
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*/
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public static Message obtain() {
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synchronized (mPoolSync) {
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if (mPool != null) {
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Message m = mPool;
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mPool = m.next;
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m.next = null;
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mPoolSize--;
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return m;
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}
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}
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return new Message();
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}
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/**
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* Same as {@link #obtain()}, but copies the values of an existing
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* message (including its target) into the new one.
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* @param orig Original message to copy.
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* @return A Message object from the global pool.
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*/
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public static Message obtain(Message orig) {
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Message m = obtain();
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m.what = orig.what;
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m.arg1 = orig.arg1;
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m.arg2 = orig.arg2;
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m.obj = orig.obj;
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m.replyTo = orig.replyTo;
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if (orig.data != null) {
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m.data = new Bundle(orig.data);
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}
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m.target = orig.target;
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m.callback = orig.callback;
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return m;
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}
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/**
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* Same as {@link #obtain()}, but sets the value for the <em>target</em> member on the Message returned.
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* @param h Handler to assign to the returned Message object's <em>target</em> member.
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* @return A Message object from the global pool.
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*/
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public static Message obtain(Handler h) {
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Message m = obtain();
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m.target = h;
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return m;
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}
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/**
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* Same as {@link #obtain(Handler)}, but assigns a callback Runnable on
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* the Message that is returned.
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* @param h Handler to assign to the returned Message object's <em>target</em> member.
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* @param callback Runnable that will execute when the message is handled.
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* @return A Message object from the global pool.
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*/
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public static Message obtain(Handler h, Runnable callback) {
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Message m = obtain();
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m.target = h;
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m.callback = callback;
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return m;
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}
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/**
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* Same as {@link #obtain()}, but sets the values for both <em>target</em> and
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* <em>what</em> members on the Message.
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* @param h Value to assign to the <em>target</em> member.
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* @param what Value to assign to the <em>what</em> member.
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* @return A Message object from the global pool.
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*/
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public static Message obtain(Handler h, int what) {
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Message m = obtain();
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m.target = h;
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m.what = what;
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return m;
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}
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/**
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* Same as {@link #obtain()}, but sets the values of the <em>target</em>, <em>what</em>, and <em>obj</em>
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* members.
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* @param h The <em>target</em> value to set.
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* @param what The <em>what</em> value to set.
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* @param obj The <em>object</em> method to set.
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* @return A Message object from the global pool.
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*/
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public static Message obtain(Handler h, int what, Object obj) {
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Message m = obtain();
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m.target = h;
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m.what = what;
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m.obj = obj;
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return m;
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}
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/**
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* Same as {@link #obtain()}, but sets the values of the <em>target</em>, <em>what</em>,
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* <em>arg1</em>, and <em>arg2</em> members.
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*
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* @param h The <em>target</em> value to set.
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* @param what The <em>what</em> value to set.
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* @param arg1 The <em>arg1</em> value to set.
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* @param arg2 The <em>arg2</em> value to set.
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* @return A Message object from the global pool.
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*/
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public static Message obtain(Handler h, int what, int arg1, int arg2) {
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Message m = obtain();
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m.target = h;
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m.what = what;
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m.arg1 = arg1;
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m.arg2 = arg2;
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return m;
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}
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/**
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* Same as {@link #obtain()}, but sets the values of the <em>target</em>, <em>what</em>,
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* <em>arg1</em>, <em>arg2</em>, and <em>obj</em> members.
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*
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* @param h The <em>target</em> value to set.
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* @param what The <em>what</em> value to set.
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* @param arg1 The <em>arg1</em> value to set.
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* @param arg2 The <em>arg2</em> value to set.
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* @param obj The <em>obj</em> value to set.
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* @return A Message object from the global pool.
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*/
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public static Message obtain(Handler h, int what,
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int arg1, int arg2, Object obj) {
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Message m = obtain();
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m.target = h;
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m.what = what;
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m.arg1 = arg1;
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m.arg2 = arg2;
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m.obj = obj;
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return m;
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}
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/**
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* Return a Message instance to the global pool. You MUST NOT touch
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* the Message after calling this function -- it has effectively been
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* freed.
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*/
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public void recycle() {
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synchronized (mPoolSync) {
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if (mPoolSize < MAX_POOL_SIZE) {
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clearForRecycle();
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next = mPool;
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mPool = this;
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mPoolSize++;
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}
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}
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}
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/**
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* Make this message like o. Performs a shallow copy of the data field.
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* Does not copy the linked list fields, nor the timestamp or
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* target/callback of the original message.
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*/
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public void copyFrom(Message o) {
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this.what = o.what;
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this.arg1 = o.arg1;
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this.arg2 = o.arg2;
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this.obj = o.obj;
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this.replyTo = o.replyTo;
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if (o.data != null) {
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this.data = (Bundle) o.data.clone();
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} else {
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this.data = null;
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}
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}
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/**
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* Return the targeted delivery time of this message, in milliseconds.
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*/
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public long getWhen() {
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return when;
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}
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public void setTarget(Handler target) {
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this.target = target;
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}
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/**
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* Retrieve the a {@link android.os.Handler Handler} implementation that
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* will receive this message. The object must implement
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* {@link android.os.Handler#handleMessage(android.os.Message)
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* Handler.handleMessage()}. Each Handler has its own name-space for
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* message codes, so you do not need to
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* worry about yours conflicting with other handlers.
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*/
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public Handler getTarget() {
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return target;
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}
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/**
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* Retrieve callback object that will execute when this message is handled.
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* This object must implement Runnable. This is called by
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* the <em>target</em> {@link Handler} that is receiving this Message to
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* dispatch it. If
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* not set, the message will be dispatched to the receiving Handler's
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* {@link Handler#handleMessage(Message Handler.handleMessage())}.
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*/
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public Runnable getCallback() {
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return callback;
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}
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/**
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* Obtains a Bundle of arbitrary data associated with this
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* event, lazily creating it if necessary. Set this value by calling
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* {@link #setData(Bundle)}. Note that when transferring data across
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* processes via {@link Messenger}, you will need to set your ClassLoader
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* on the Bundle via {@link Bundle#setClassLoader(ClassLoader)
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* Bundle.setClassLoader()} so that it can instantiate your objects when
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* you retrieve them.
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* @see #peekData()
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* @see #setData(Bundle)
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*/
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public Bundle getData() {
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if (data == null) {
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data = new Bundle();
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}
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return data;
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}
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/**
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* Like getData(), but does not lazily create the Bundle. A null
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* is returned if the Bundle does not already exist. See
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* {@link #getData} for further information on this.
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* @see #getData()
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* @see #setData(Bundle)
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*/
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public Bundle peekData() {
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return data;
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}
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/**
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* Sets a Bundle of arbitrary data values. Use arg1 and arg1 members
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* as a lower cost way to send a few simple integer values, if you can.
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* @see #getData()
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* @see #peekData()
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*/
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public void setData(Bundle data) {
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this.data = data;
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}
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/**
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* Sends this Message to the Handler specified by {@link #getTarget}.
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* Throws a null pointer exception if this field has not been set.
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*/
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public void sendToTarget() {
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target.sendMessage(this);
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}
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/*package*/ void clearForRecycle() {
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what = 0;
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arg1 = 0;
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arg2 = 0;
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obj = null;
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replyTo = null;
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when = 0;
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target = null;
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callback = null;
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data = null;
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}
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/** Constructor (but the preferred way to get a Message is to call {@link #obtain() Message.obtain()}).
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*/
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public Message() {
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}
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public String toString() {
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return toString(SystemClock.uptimeMillis());
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}
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String toString(long now) {
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StringBuilder b = new StringBuilder();
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b.append("{ what=");
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b.append(what);
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b.append(" when=");
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TimeUtils.formatDuration(when-now, b);
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if (arg1 != 0) {
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b.append(" arg1=");
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b.append(arg1);
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}
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if (arg2 != 0) {
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b.append(" arg2=");
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b.append(arg2);
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}
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if (obj != null) {
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b.append(" obj=");
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b.append(obj);
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}
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b.append(" }");
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return b.toString();
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}
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public static final Parcelable.Creator<Message> CREATOR
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= new Parcelable.Creator<Message>() {
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public Message createFromParcel(Parcel source) {
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Message msg = Message.obtain();
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msg.readFromParcel(source);
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return msg;
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}
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public Message[] newArray(int size) {
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return new Message[size];
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}
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};
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public int describeContents() {
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return 0;
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}
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public void writeToParcel(Parcel dest, int flags) {
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if (callback != null) {
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throw new RuntimeException(
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"Can't marshal callbacks across processes.");
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}
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dest.writeInt(what);
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dest.writeInt(arg1);
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dest.writeInt(arg2);
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if (obj != null) {
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try {
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Parcelable p = (Parcelable)obj;
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dest.writeInt(1);
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dest.writeParcelable(p, flags);
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} catch (ClassCastException e) {
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throw new RuntimeException(
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"Can't marshal non-Parcelable objects across processes.");
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}
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} else {
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dest.writeInt(0);
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}
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dest.writeLong(when);
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dest.writeBundle(data);
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Messenger.writeMessengerOrNullToParcel(replyTo, dest);
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}
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private final void readFromParcel(Parcel source) {
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what = source.readInt();
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arg1 = source.readInt();
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arg2 = source.readInt();
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if (source.readInt() != 0) {
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obj = source.readParcelable(getClass().getClassLoader());
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}
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when = source.readLong();
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data = source.readBundle();
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replyTo = Messenger.readMessengerOrNullFromParcel(source);
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}
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}
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