我有一个带有异步任务的程序和一个广播接收器来发送结果代码，这样Asynctask就会知道应用程序正在运行。但它崩溃了，说接收器在主要活动中没有被注册。我在主要活动中注册了一个接收器，另一个接收器在AsyncTask Activity中。所以这里是代码和日志猫。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mFragmentManager = getFragmentManager();
addFriendsFragment();
// The feed is fresh if it was downloaded less than 2 minutes ago
mIsFresh = (System.currentTimeMillis() - getFileStreamPath(
TWEET_FILENAME).lastModified()) < TWO_MIN;
ensureData();
}
// Add Friends Fragment to Activity
private void addFriendsFragment() {
mFriendsFragment = new FriendsFragment();
mFriendsFragment.setArguments(getIntent().getExtras());
FragmentTransaction transaction = mFragmentManager.beginTransaction();
transaction.add(R.id.fragment_container, mFriendsFragment);
transaction.commit();
}
// If stored Tweets are not fresh, reload them from network
// Otherwise, load them from file
private void ensureData() {
log("In ensureData(), mIsFresh:" + mIsFresh);
if (!mIsFresh) {
// TODO:
// Show a Toast Notification to inform user that
// the app is "Downloading Tweets from Network"
log ("Issuing Toast Message");
Toast toast = Toast.makeText(getApplicationContext(),
"Downloading Tweets from Network",Toast.LENGTH_LONG);
toast.show();
// TODO:
// Start new AsyncTask to download Tweets from network
new DownloaderTask(MainActivity.this).execute(MainActivity.URL_LGAGA, MainActivity.URL_RBLACK, MainActivity.URL_TSWIFT);
// Set up a BroadcastReceiver to receive an Intent when download
// finishes.
mRefreshReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
log("BroadcastIntent received in MainActivity");
// TODO:
// Check to make sure this is an ordered broadcast
// Let sender know that the Intent was received
// by setting result code to RESULT_OK
sendOrderedBroadcast(new Intent(), null, null, null, RESULT_OK, null, null );
}
};
} else {
loadTweetsFromFile();
parseJSON();
updateFeed();
}
}
// Called when new Tweets have been downloaded
public void setRefreshed(String[] feeds) {
mRawFeeds[0] = feeds[0];
mRawFeeds[1] = feeds[1];
mRawFeeds[2] = feeds[2];
parseJSON();
updateFeed();
mIsFresh = true;
};
// Called when a Friend is clicked on
@Override
public void onItemSelected(int position) {
mFeedSelected = position;
mFeedFragment = addFeedFragment();
if (mIsFresh) {
updateFeed();
}
}
// Calls FeedFragement.update, passing in the
// the tweets for the currently selected friend
void updateFeed() {
if (null != mFeedFragment)
mFeedFragment.update(mProcessedFeeds[mFeedSelected]);
}
// Add FeedFragment to Activity
private FeedFragment addFeedFragment() {
FeedFragment feedFragment;
feedFragment = new FeedFragment();
FragmentTransaction transaction = mFragmentManager.beginTransaction();
transaction.replace(R.id.fragment_container, feedFragment);
transaction.addToBackStack(null);
transaction.commit();
mFragmentManager.executePendingTransactions();
return feedFragment;
}
// Register the BroadcastReceiver
@Override
protected void onResume() {
super.onResume();
// TODO:
// Register the BroadcastReceiver to receive a
// DATA_REFRESHED_ACTION broadcast
IntentFilter intentFilter = new IntentFilter(DATA_REFRESHED_ACTION);
registerReceiver(mRefreshReceiver, intentFilter);
}
@Override
protected void onPause() {
// TODO:
// Unregister the BroadcastReceiver
unregisterReceiver(mRefreshReceiver);
super.onPause();
}
logcat的：
02-26 01:39:58.466: E/AndroidRuntime(943): FATAL EXCEPTION: main
02-26 01:39:58.466: E/AndroidRuntime(943): java.lang.RuntimeException: Unable to pause activity {course.labs.notificationslab/course.labs.notificationslab.MainActivity}: java.lang.IllegalArgumentException: Receiver not registered: null
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3064)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3019)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ActivityThread.handlePauseActivity(ActivityThread.java:2997)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ActivityThread.access$800(ActivityThread.java:141)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1273)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.os.Handler.dispatchMessage(Handler.java:99)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.os.Looper.loop(Looper.java:137)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ActivityThread.main(ActivityThread.java:5103)
02-26 01:39:58.466: E/AndroidRuntime(943): at java.lang.reflect.Method.invokeNative(Native Method)
02-26 01:39:58.466: E/AndroidRuntime(943): at java.lang.reflect.Method.invoke(Method.java:525)
02-26 01:39:58.466: E/AndroidRuntime(943): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
02-26 01:39:58.466: E/AndroidRuntime(943): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
02-26 01:39:58.466: E/AndroidRuntime(943): at dalvik.system.NativeStart.main(Native Method)
02-26 01:39:58.466: E/AndroidRuntime(943): Caused by: java.lang.IllegalArgumentException: Receiver not registered: null
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.LoadedApk.forgetReceiverDispatcher(LoadedApk.java:662)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ContextImpl.unregisterReceiver(ContextImpl.java:1372)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.content.ContextWrapper.unregisterReceiver(ContextWrapper.java:468)
02-26 01:39:58.466: E/AndroidRuntime(943): at course.labs.notificationslab.MainActivity.onPause(MainActivity.java:195)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.Activity.performPause(Activity.java:5235)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.Instrumentation.callActivityOnPause(Instrumentation.java:1233)
02-26 01:39:58.466: E/AndroidRuntime(943): at android.app.ActivityThread.performPauseActivity(ActivityThread.java:3050)
02-26 01:39:58.466: E/AndroidRuntime(943): ... 12 more
这是AsyncTask的代码，但LogCat表示错误是主要的。
mApplicationContext.sendOrderedBroadcast(
new Intent(MainActivity.DATA_REFRESHED_ACTION),
null,
new BroadcastReceiver() {
final String failMsg = "Download has failed. Please retry Later.";
final String successMsg = "Download completed successfully.";
@Override
public void onReceive(Context context, Intent intent) {
log("Entered result receiver's onReceive() method");
// TODO: Check whether the result code is RESULT_OK
if (getResultCode() == Activity.RESULT_OK) {
// TODO: If so, create a PendingIntent using the
// restartMainActivityIntent and set its flags
// to FLAG_UPDATE_CURRENT
final PendingIntent pendingIntent = PendingIntent.getActivity(mApplicationContext,
0, restartMainActivtyIntent, PendingIntent.FLAG_UPDATE_CURRENT);
// Uses R.layout.custom_notification for the
// layout of the notification View. The xml
// file is in res/layout/custom_notification.xml
RemoteViews mContentView = new RemoteViews(
mApplicationContext.getPackageName(),
R.layout.custom_notification);
// TODO: Set the notification View's text to
// reflect whether or the download completed
// successfully
if (success){
mContentView.setTextViewText(MY_NOTIFICATION_ID, successMsg);
}else{
mContentView.setTextViewText(MY_NOTIFICATION_ID, failMsg);
}
// TODO: Use the Notification.Builder class to
// create the Notification. You will have to set
// several pieces of information. You can use
// android.R.drawable.stat_sys_warning
// for the small icon. You should also setAutoCancel(true).
// TODO: Send the notification
Notification notification = new Notification.Builder(mApplicationContext)
.setContentIntent(pendingIntent)
.setSmallIcon(android.R.drawable.stat_sys_warning)
.setAutoCancel(true)
.build();
NotificationManager notificationManager =
(NotificationManager)mApplicationContext.getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.notify(MY_NOTIFICATION_ID, notification);
log("Notification Area Notification sent");
}
}
},
null,
0,
null,
null);
}
答案 0 :(得分：2)
尝试如下......
mRefreshReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
log("BroadcastIntent received in MainActivity");
}
}
在onResume() ...
@Override
protected void onResume() {
super.onResume();
IntentFilter filter = new IntentFilter(DATA_REFRESHED_ACTION);
registerReceiver(mRefreshReceiver, filter);
}
在AsyncTask ....
Intent intent = new Intent(DATA_REFRESHED_ACTION);
sendOrderedBroadcast(intent, null, new BroadcastReceiver() {
@SuppressLint("NewApi")
@Override
public void onReceive(Context context, Intent intent) {
log("BroadcastIntent received in MainActivity");
}
}, null, Activity.RESULT_OK, null, null);
}
您可以按照以下链接...
答案 1 :(得分：0)
因为您的广播接收器仅在（！mIsFresh）时创建
因此，在某些情况下，由于mIsFresh，您的广播接收器不是实例
因此，onResume注册广播接收器的空值
当onPause尝试取消注册时，会发生错误。