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      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 import android.os.Handler;
     20 import android.os.Message;
     21 
     22 import java.lang.ref.WeakReference;
     23 
     24 /** @hide */
     25 public class Registrant
     26 {
     27     public
     28     Registrant(Handler h, int what, Object obj)
     29     {
     30         refH = new WeakReference(h);
     31         this.what = what;
     32         userObj = obj;
     33     }
     34 
     35     public void
     36     clear()
     37     {
     38         refH = null;
     39         userObj = null;
     40     }
     41 
     42     public void
     43     notifyRegistrant()
     44     {
     45         internalNotifyRegistrant (null, null);
     46     }
     47 
     48     public void
     49     notifyResult(Object result)
     50     {
     51         internalNotifyRegistrant (result, null);
     52     }
     53 
     54     public void
     55     notifyException(Throwable exception)
     56     {
     57         internalNotifyRegistrant (null, exception);
     58     }
     59 
     60     /**
     61      * This makes a copy of @param ar
     62      */
     63     public void
     64     notifyRegistrant(AsyncResult ar)
     65     {
     66         internalNotifyRegistrant (ar.result, ar.exception);
     67     }
     68 
     69     /*package*/ void
     70     internalNotifyRegistrant (Object result, Throwable exception)
     71     {
     72         Handler h = getHandler();
     73 
     74         if (h == null) {
     75             clear();
     76         } else {
     77             Message msg = Message.obtain();
     78 
     79             msg.what = what;
     80 
     81             msg.obj = new AsyncResult(userObj, result, exception);
     82 
     83             h.sendMessage(msg);
     84         }
     85     }
     86 
     87     /**
     88      * NOTE: May return null if weak reference has been collected
     89      */
     90 
     91     public Message
     92     messageForRegistrant()
     93     {
     94         Handler h = getHandler();
     95 
     96         if (h == null) {
     97             clear();
     98 
     99             return null;
    100         } else {
    101             Message msg = h.obtainMessage();
    102 
    103             msg.what = what;
    104             msg.obj = userObj;
    105 
    106             return msg;
    107         }
    108     }
    109 
    110     public Handler
    111     getHandler()
    112     {
    113         if (refH == null)
    114             return null;
    115 
    116         return (Handler) refH.get();
    117     }
    118 
    119     WeakReference   refH;
    120     int             what;
    121     Object          userObj;
    122 }
    123 
    124