I'm working in a application that I have a button to login, which checks if this account exists already in the database and if so, go to the next activity.
But nothing is showing in the layout screen.
The log cat is repeating the following message:
Skipped 48 frames! The application may be doing too much work on its main thread.
What is causing this?
I suggest you to take a look at http://developer.android.com/guide/components/processes-and-threads.html
Take some time studying how process and threads work on an Android system. It worth the effort.
Quoting a specific sentence related to your issue:
When your app performs intensive work in response to user interaction,
this single thread model can yield poor performance unless you
implement your application properly. Specifically, if everything is
happening in the UI thread, performing long operations such as network
access or database queries will block the whole UI. When the thread is
blocked, no events can be dispatched, including drawing events. From
the user's perspective, the application appears to hang. Even worse,
if the UI thread is blocked for more than a few seconds (about 5
seconds currently) the user is presented with the infamous
"application not responding" (ANR) dialog. The user might then decide
to quit your application and uninstall it if they are unhappy.
Good luck !
I am working on an Android app that displays a continuous custom-rendered animation on the title screen and thus doesn't really enter the idle state when it's done loading. On most devices I've tested, everything runs fine, but Samsung's Galaxy S2 kills the app after a few seconds. I don't get a stack trace or any output of the System.out output that I put into the onPause event handler and the default uncaught exception handler, so it doesn't seem to be a normal exit or an Exception in my code.
The only output I get in LogCat is the following:
Launch timeout has expired, giving up wake lock!
Sending signal. PID: 22344 SIG: 3
handleActivityTimeout pid=[22344] cnt=10
Process ... (pid 22344) has died.
There are several related posts here on SO (1, 2, 3, 4), but they all seem to trigger the issue slightly differently (alarm, recursive loops, network requests in the UI thread, ...). The last one links to a Google Groups discussion that says that this error message can simply be ignored. An approach I'd rather not take since it causes my app to actually crash on the Galaxy S2 (and maybe others?).
Basically what I did was to write a custom View that renders the next animation-frame in its onDraw() method and then calls postInvalidate() right before returning from onDraw(). In case it matters: My first postInvalidate() call happens during onCreate(...).
The rendering is very quick and runs at 40+ frames per second on that device and well over 60 fps on more modern phones. So control goes back to the event loop very frequently and the app is also very responsive. Yet, the Galaxy seems to think that it has crashed and kills it (if that is even the reason for my app dying there). The thing is: If I am quick enough to click on a menu-item in my app to end up on a screen without an animation to break out of the "tail-recursive" postInvalidate() once, everything runs fine. Even if I then go back to the title screen for a long time where the animation runs again.
So, of course, I could probably just use postInvalidateDelayed(...) once to break out of the start-up check, but that seems like a bit of a hacky solution and I don't know if there might be any other devices out there that might consider my app dead at a later stage (not just during start-up) and kill it.
Is there something fundamentally wrong with using postInvalidate() in the way I'm doing? Is there a way to fix it? I would like to avoid having to move to a separate thread since that opens a whole other can of worms as far as passing events back and forth between the UI and that thread. I know it wouldn't be the end of the world and using a SurfaceView, it might even lead to a slight performance improvement, but it's really just not necessary from a user experience point of view (everything runs perfectly smooth), so I'd like to avoid the involved additional opportunities for issues (multi-threading is notoriously difficult to debug).
I have searched on the internet regarding what an ANR is. And I studied those references as well. But I don't get details regarding a crash in Android.
Can someone tell me the difference between ANR(Android not Responding) and a crash in Android?
ANR stands for Application Not Responding.
An ANR will occur if you are running a process on the UI thread which takes a long time, usually around 5 seconds. During this time the GUI (Graphical User Interface) will lock up which will result in anything the user presses will not be actioned. After the 5 seconds approx has occurred, if the thread still hasn't recovered then an ANR dialogue box is shown informing the user that the application is not responding and will give the user the choice to either wait, in the hope that the app will eventually recover, or to force close the app.
A crash is when an exception within the app has been thrown which has not been handled. For example, if you try to set the text of an EditText component, but the EditText is null and there is no try catch statement to catch the exception that your app will crash and will be force closed. The user will not see what caused the crash, they will be shown a dialogue telling that the app has force closed unexpectedly and will give them the option to send a bug report. In this example if you were to look in the bug report you would see the error caused by java.lang.NullPointerException.
ANR (Application Not Responding) is due to handling a long running task in the main (UI) thread. If the main thread is stopped for more than 5 seconds, the user will get an ANR.
Crashes are due to exceptions and errors like NullPointerException, ClassNotFoundException, typecasting or parsing errors, etc. ANR also causes a crash of the application.
Note: Never perform a long-running task on the UI thread.
Reference ANR
ANR and Crash Examples:
This question already has an accepted answer, but I am adding 2 simple examples to understand ANR and Crash better.
ANR:
// this will produce an ANR on your app
int i = 0;
while(true) {
i++;
}
Crash:
// this will crash your app : will produce java.lang.ArithmeticException
int value = 5, i = 0;
int result = value / i;
Application Not Responding (ANR):
ANR will display in the following conditions:
Response to the input event (such as key press or screen touch even) within 5 Sec.
A Broadcast Receiver hasn’t finished executing within 10 Sec.
How to avoid ANRs?
Create a different worker thread for long running operations like database operations, network operations etc.
Reinforce Responsiveness:
In android app usually, 100 to 200 ms is the threshold beyond which user will feel that app is slow. Following are the tips through which we can show application more responsive.
Show progress dialog whenever you are doing any background work and a user is waiting for the response.
For games specifically, do calculations for moves in the worker thread.
Show splash screen if your application has time-consuming initial setup.
Crash:
The crash is unhandled condition into the application and it will forcefully close our application. Some of the examples of crashes are like Nullpointer exception, Illegal state exception etc.
ANR stands for Application Not Responding, which means that your app does not register events on the UI Thread anymore because a long running operation is executed there
ANR: It is called when anything your application is doing in the UI thread that
takes a long time to complete (5 sec approx)
Reference: ANR
Crash: It is called when your Application gets some Error or Exception raised by the DVM
ANR also caused by-
No response to an input event (such as key press or screen touch events) within 5 seconds.
A BroadcastReceiver hasn't finished executing within 10 seconds.
ANR stands for Application Not Responding and its occurs when long operation takes place into Main thread......
Crash are due to exception and error like Nullpoint,
ANR stands for Application Not Responding.
It can occur due to many reasons like if an application blocks on some I/O operation on the UI thread so the system can’t process incoming user input events. Or perhaps the app spends too much time building an elaborate in-memory structure or computing the next move in the UI thread.
Blocking the main thread, won't result in a crash, but a popup will be displayed to let users kills the app after 5 seconds.
But For Crash, the main reason is the human errors.
Most of the time an app crashes is because of a coding/design error made by human
Human Errors
Lack of testing
Null Pointer exception
OutofMemory
Example :
This is common when a programmer makes a reference to an object or variable that does not exist, basically creating a null-pointer error.
If you have a bad connection, that can also make your apps crash. The app could also have memory management problems.
Please see my answer for the type of android specific exception which may cause the crash.
Android Specific Exception
ANR for ex: if You are downloading huge amount data in ui thread, meny other possibilities like insufficient memory etc it will come.. probably it leads to crashes in android , We can't say both are same one follows other
[ANR and Crash Different][1]
Android applications normally run entirely on a single thread by default the “UI thread” or
“main thread”. This means anything your application is doing in the UI thread that takes a long time to complete can trigger the ANR dialog because your application is not giving itself a chance to handle the input event or intent broadcasts.
ANR: Basically due to a long running task on main thread.
There are some common patterns to look for when diagnosing ANRs:
The app is doing slow operations involving I/O on the main thread.
The app is doing a long calculation on the main thread.
The main thread is doing a synchronous binder call to another process, and that other process is taking a long time to return.
The main thread is blocked waiting for a synchronized block for a long operation that is happening on another thread.
The main thread is in a deadlock with another thread, either in your process or via a binder call. The main thread is not just waiting for a long operation to finish, but is in a deadlock situation.
The following techniques can help you find out which of these causes is causing your ANRs.
CRASH:
Reason for crashs can be many. Some reasons are obvious, like checking for a null value or empty string, but others are more subtle, like passing invalid arguments to an API or even complex multithreaded interactions
This is good article at developer portal.
It gives clarity in detail about ANR.
https://developer.android.com/training/articles/perf-anr.html
I would like to know whether it is a good practice to write for loop that loops around 400-500 times inside android main thread or should i go for an another thread. Thanks in advance.
Since you say the loop is processing several hundred coordinates, it should definitely be an AsyncTask or a background thread. Even if the user cannot interact with the UI in that period, this will allow you to show a spinner or dialog for that duration. Further, if the UI thread is unresponsive for more than a certain amount of time, the OS considers the app to have crashed, and gives the user the 'This app has stopped responding' dialog box.
I am new in android and working on a maintenance project
Application crashes if no internet connection while creating Soap Request
Following is screenshot of LogCat, Can any body tell me Whats the reason for crashing.
Amit Battan
You are getting a ANR. It stands for Application Not Resoponding.
Android kills applications which are unresponsive to user interactions. Basically when you are doing heavy processing and the user clicks on a button if your application doesn't respond to the click event within 5 seconds.
In your case, if the internet connection is not there I think your application keeps trying to connect and never comes out of this. Hence the ANR. Consider having a timeout for the request..
Check this link for more details on ANR.
ANR happens when some long operation takes place in the "main" thread. This is the event loop thread, and if it is busy, Android cannot process any further GUI events in the application, and thus throws up an ANR dialog.
Any task that will take more time should not be performed in the UI thread, and should be moved to either an AsyncTask or a Thread & Handler.
Check the /data/anr/traces.txt file.
put the all the downloading task in a thread and check that once....
Actually android allocates some time to every process if the process does not complete its action in that particular time then ANR error will come.