true

I am developing an application, and everytime I run it, I get the message:

Unfortunately, MyApp has stopped.

What can I do to solve this?


About this question - obviously inspired by What is a stack trace, and how can I use it to debug my application errors?, there are lots of questions stating that their application has crashed, without any further detail. This question aims to instruct novice Android programmers on how to try and fix their problems themselves, or ask the right questions.

16 upvote
  flag
I've seen many questions getting closed as dupes with this. This is a good reference for helping people post relevant data in their questions. However, this isn't a duplicate of any root problem there but just methodology for digging out the root problem. I think it would be better just to provide the link to this question as a reference and not close as duplicate. – laalto
25 upvote
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I think the close function is perfect for this. Most of these questions show little knowledge of the basic debugging skills. Putting them on hold provides a chance for them to clarify their problem, using the method as stated in the answer. Better yet, they might be able to solve the problem themselves. This discussion might be better suited for meta.//allinonescript.com though. – nhaarman
upvote
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This question is too vague. A better question would be 'using [myIDE] how do I debug' an Android application that's displaying the error 'Unfortunately, MyApp has stopped' – Chris Halcrow
3 upvote
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@ChrisHalcrow This Q/A is not about debugging at all. It is about guiding beginners in Android how to deal with app crashes. – nhaarman
upvote
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//allinonescript.com/questions/26609734/….. enable the multidex becoz error in convert to apk – RejoylinLokeshwaran

15 Answers 11

up vote 524 down vote accepted

This answer describes the process of retrieving the stack trace. Already have the stack trace? Read up on stack traces in "What is a stack trace, and how can I use it to debug my application errors?"

The Problem

Your application quit because an uncaught RuntimeException was thrown.
The most common of these is the NullPointerException.

How to solve it?

Every time an Android application crashes (or any Java application for that matter), a Stack trace is written to the console (in this case, logcat). This stack trace contains vital information for solving your problem.

Android Studio

Finding the stack trace in Android Studio

In the bottom bar of the window, click on the Android button. Alternatively, you can press alt+6. Make sure your emulator or device is selected in the Devices panel. Next, try to find the stack trace, which is shown in red. There may be a lot of stuff logged into logcat, so you may need to scroll a bit. An easy way to find the stack trace is to clear the logcat (using the recycle bin on the right), and let the app crash again.

Eclipse

Finding the stack trace in Eclipse

In the top right corner, click the DDMS button. If it is not there, you might need to add it first using the Open Perspective button to the left of the Java button. You will find the logcat pane at the bottom. First, make sure your device is selected in the topleft devices panel. Next, try to find the stack trace, which is shown in red. Again, there may be a lot of stuff logged into logcat, so you may need to scroll a bit. An easy way to find the stack trace here is to clear the logcat (using the clear log button on the top right), and let the app crash again. You should also click on the package name of your app, if it is not already selected. This will filter out only the log message made by your app.

I have found the stack trace, now what?

Yay! You're halfway to solving your problem.
You only need to find out what exactly made your application crash, by analyzing the stack trace.

Read up on stack traces in "What is a stack trace, and how can I use it to debug my application errors?"

I still can't solve my problem!

If you've found your Exception and the line where it occurred, and still cannot figure out how to fix it, don't hesitate to ask a question on StackOverflow.

Try to be as concise as possible: post the stack trace, and the relevant code (e.g. a few lines up to the line which threw the Exception).

27 upvote
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I know this post is old: but if you use IntelliJ IDEA you can go inside Android > Devices|Logcat and add a new filter (i.imgur.com/145dtkx.png), and filter it for by Log Message here you can put FATAL EXCEPTION (i.imgur.com/HpELhaU.png) so in this Box you can read all Exceptions which are throw by your application. With this you don't need to clear logcat and do the crash again. I think Android Studio have this option too. – Marco Acierno
1 upvote
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Filtering logcat in Eclipse can be done by typing in the java package name in the application name field of the filter. – Stephane
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I think the main point is understanding the trace back one gets when the exception happens. FCs are a bit bad when there is no trace back or not a usable one, which is where it gets hairy. but I think this explanation is a nice first intro in finding/identifying such bugs. – DooMMasteR
2 upvote
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Things are easy when your logcat has some trace of error, but what in case logcat has nothing? //allinonescript.com/questions/32455645/… – Marian Paździoch
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For IntelliJ users, the window will be "Android Monitor" (kind of self explanatory) – sparkyShorts
2 upvote
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The problem is the line does not contain the error which is written and pointed by the stack trace. – Hilal

First you check which point your app has crashed (Unfortunately, MyApp has stopped.). For this you can use Log.e("TAG","Message");, using this line you can see you app log in logcat.

After that you find which point your app has stopped its very easy to solve at your side.

You can also get this error message on its own, without any stack trace or any further error message.

In this case you need to make sure your Android manifest is configured correctly (including any manifest merging happening from a library and any activity that would come from a library), and pay particular attention to the first activity displayed in your application in your manifest files.

3 upvote
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I would be interested if you could upload a project that demonstrates this phenomenon. – CommonsWare

You can use Google's ADB tool to get Logcat file to analyze the issue.

adb logcat > logcat.txt

open logcat.txt file and search for your application name. There should be information on why it failed, the line number ,Class name etc.

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This is great, it'll show you quickly anything going on on the device even if your debugger is failing to catch it, which can happen for Xamarin if the runtime fails to load. – jvenema
1 upvote
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I couldn't see why my app was crashing in the android studio logcat, there were no errors at all. This answer gave me what I needed. Later on however I realised that I had some filter on in the studio logcat which was preventing me from seeing the error. I switched back to "Show only selected application" and I was back up and running. – Yannick
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you should add -d, otherwise you nave to ctrl-C to exit logcat. I do adb logcat -v time -d > filename.txt – Karakuri

Just check the error in log cat.

You get the log cat option from in eclipse:

window->show view->others->Android->Logcat

Log cat contains error.

Other wise you can also check the error by executing an application in debug mode. Firstly set breakpoint after that by doing:

right click on project->debug as->Android application

Check your Logcat message and see your Manifest file. There should be something missing like defining the Activity,User permission`, etc.

You have to check the Stack trace

How to do that?

on Your IDE Check the windows form LOGCAT

If you cant see the logcat windows go to this path and open it

window->show view->others->Android->Logcat

if you are using Google-Api go to this path

adb logcat > logcat.txt

You can use any of these tools:

  1. adb logcat

  2. adb logcat > logs.txt (you can use editors to open and search errors.)

  3. eclipse logcat (If not visible in eclipse, Go to Windows->Show View->Others->Android->LogCat)

  4. Android Debug Monitor or Android Device Monitor(type command monitor or open through UI)

enter image description here

  1. Android Studio

I suggest to use Android Debug Monitor, it is good. Because eclipse hangs when too many logs are there, and through adb logcat filter and all difficult.

Use the LogCat and try to find what is causing the app to crash.

To see Logcat if you use Android Studio then Press ALT + 6 or

if you use Eclipse then Window -> Open Perspective -> Other - LogCat

Go to the LogCat, from the drop down menu select error. This will contain all the required information to help you debug. If that doesn't help, post the LogCat as an edit to your question and somebody will help you out.

Let me share a basic Logcat analysis for when you meet a Force Close (when app stops working).

DOCS

Basic tool from Android to collect/analyse logs is the logcat.

HERE is the Android's page about logcat

If you use android Studio, you can also check this LINK.

Capturing

Basically, you can MANUALLY capture logcat with following command (or just check AndroidMonitor window in AndroidStudio):

adb logcat

There's a lot of parameters you can add to command which helps you to filter and display the message that you want... This is personal... I always use the command below to get the message timestamp:

adb logcat -v time

You can redirect the output to a file and analyze it in a Text Editor.

Analyzing

If you app is Crashing, you'll get something like:

07-09 08:29:13.474 21144-21144/com.example.khan.abc D/AndroidRuntime: Shutting down VM
07-09 08:29:13.475 21144-21144/com.example.khan.abc E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.khan.abc, PID: 21144
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.app.FragmentActivity.onBackPressed()' on a null object reference
     at com.example.khan.abc.AudioFragment$1.onClick(AudioFragment.java:125)
     at android.view.View.performClick(View.java:4848)
     at android.view.View$PerformClick.run(View.java:20262)
     at android.os.Handler.handleCallback(Handler.java:815)
     at android.os.Handler.dispatchMessage(Handler.java:104)
     at android.os.Looper.loop(Looper.java:194)
     at android.app.ActivityThread.main(ActivityThread.java:5631)
     at java.lang.reflect.Method.invoke(Native Method)
     at java.lang.reflect.Method.invoke(Method.java:372)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)
07-09 08:29:15.195 21144-21144/com.example.khan.abc I/Process: Sending signal. PID: 21144 SIG: 9

This part of the log shows you a lot of information:

  • When the issue happened: 07-09 08:29:13.475

It is important to check when the issue happened... You may find several errors in a log... you must be sure that you are checking the proper messages :)

  • Which app crashed: com.example.khan.abc

This way, you know which app crashed (to be sure that you are checking the logs about your message)

  • Which ERROR: java.lang.NullPointerException

A NULL Pointer Exception error

  • Detailed info about the error: Attempt to invoke virtual method 'void android.support.v4.app.FragmentActivity.onBackPressed()' on a null object reference

You tried to call method onBackPressed() from a FragmentActivity object. However, that object was null when you did it.

  • Stack Trace: Stack Trace shows you the method invocation order... Sometimes, the error happens in the calling method (and not in the called method).

    at com.example.khan.abc.AudioFragment$1.onClick(AudioFragment.java:125)

Error happened in file com.example.khan.abc.AudioFragment.java, inside onClick() method at line: 125 (stacktrace shows the line that error happened)

It was called by:

at android.view.View.performClick(View.java:4848)

Which was called by:

at android.view.View$PerformClick.run(View.java:20262)

which was called by:

at android.os.Handler.handleCallback(Handler.java:815)

etc....

Overview

This was just an overview... Not all logs are simple etc... It is just to share the idea and provide a entry-level information to you...

I hope I could help you someway... Regards

Alternative Solution for Handling Unfortunately App crash.

We get this message whenever our App forced closed by any exceptions that is not handled in android or in our application.

So we just need to take care of it when we are writing the code that will save a lots of time in tracking any type of exceptions in android.

Steps to track the exceptions in App :-

1.Open the Logcat and view the Exception.

If you cant see the logcat windows go to this path and open it

window->show view->others->Android->Logcat 

We Use the LogCat and try to find, what is causing the app to crash.

2. Try to handle the exception which is shown in the logcat, and also check the other case's which may cause the exception .

3. Add an Uncaught Exception Handler in your Application to haldle all other exception .

I).Create a class MyExceptionHandler which implementsThread.UncaughtExceptionHandler

public class MyExceptionHandler implements
    Thread.UncaughtExceptionHandler {
private final Context myContext;
private final Class<?> myActivityClass;

public MyExceptionHandler(Context context, Class<?> c) {

    myContext = context;
    myActivityClass = c;
}

public void uncaughtException(Thread thread, Throwable exception) {
    StringWriter stackTrace = new StringWriter();
    exception.printStackTrace(new PrintWriter(stackTrace));
    System.err.println(stackTrace);
    // You can use LogCat too
    Intent intent = new Intent(myContext, myActivityClass);
    intent.putExtra("uncaughtException", "Exception : " + stackTrace.toString());
    intent.putExtra("stacktrace", s);
    myContext.startActivity(intent);
    //for restarting the Activity
    Process.killProcess(Process.myPid());
    System.exit(0);
}

}

II).Handle exception in any class or activity or fragment.

//We need to Caught the Unwanted exception whihc is not handled by Android:
  Thread.setDefaultUncaughtExceptionHandler(new MyExceptionHandler(this, SplashScreen.class));

It will restart the same Activity again if the app got crashed.

6 upvote
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This entirely misses the point. Adding a generic uncaught exception handler does not solve the root problem. It >>hides<< it. – Stephen C
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Any app dev that does not include this in their code is begging for 1 star reviews. This prevents ANR dialogs, the leading cause of bad reviews. – Dominic Cerisano
5 upvote
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Any app dev that does include this in their code is begging for 1 star reviews. This leads to unexpected state, unsolveable bugs and weird user experiences. – nhaarman
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Other than an exploding battery, the worst user experience is a crash dialog, which this prevents. The rest is up to the app dev, no bizarre fear-based commentary required. – Dominic Cerisano

Note: This answer is using Android Studio 2.2.2

Note 2: I am considering that your device is successfully connected.


The first thing you do when your application crashes is look into the LogCat, at the bottom of Android Studio there's a toolbar with a list of menus:

image

Click on the "Android Monitor" (The one I underlined in the image above. ^)

Now, you'll get something like this:

image

Change "Verbose" to "Error" Now it will only show you logged errors. Don't worry about all these errors (if you got them) now.

image

Ok. Now, do what you did to crash your app. After your app crashes, go to your logcat. You should find a new crash log that has a lot of at:x.x.x: and Caused by: TrumpIsPresidentException for example. Go to that Caused by: statement in your logcat.

image

Next to that Caused By:, there should be the Exception that happened. In my case, it's a RuntimeException and under it there should be a line which contains a blue link such as:

image

If that Caused by: DOESN'T have a line with a blue text somewhere under it, then look for another Caused by: that does.

Click on that blue link. It should take you to where the problem occured. In my case, it was due to this line:

throw new RuntimeException();

So, now I know why it's crashing. It's because I'm throwing the exception myself. This was an obvious error.


However, let's say I got another error:

java.lang.NullPointerException

I checked my logcat, I clicked on the blue link it gave me, and it took me here:

mTextView.setText(myString);

So, now I want to debug. According to this StackOverflow question, a NullPointerException says that something is null.

So, let's find out what is null. There's two possibilities. Either mTextView is null, or myString is null. To find out, before the mTextView.setText(mString) line, I add these two lines:

Log.d("AppDebug","mTextView is null: " + String.valueOf(mTextView == null);
Log.d("AppDebug","myString is null: " + String.valueOf(myString== null);

Now, like we did previously (We changed Verose to Error), we want to change "Error" to "Debug". Since we're logging by debugging. Here's all the Log methods:

Log.
  d means Debug
  e means error
  w means warning
  v means verbose
  i means information
  wtf means "What a terrible failure". This is similar to Log.e

So, since we used Log.d, we're checking in Debug. That's why we changed it to debug.

Notice Log.d has a first parameter,in our case "AppDebug". Click on the "No Filters" drop down menu on the top-right of the logcat. Select "Edit Filter Configuration", give a name to your filter, and in "Log Tag" put "App Debug". Click "OK". Now, you should see two lines in the logcat:

yourPackageNameAndApp: mTextView is null: true
yourPackageNameAndApp: myString is null: false

So now we know that mTextView is null.

I observe my code, now I notice something.

I have private TextView mTextView declared at the top of my class. But, I'm not defining it.

Basically I forgot to do this in my onCreate():

mTextView = (TextView) findViewById(R.id.textview_id_in_xml);

So THAT'S why mTextView is null, because I forgot to tell my app what it is. So I add that line, run my app, and now the app doesn't crash.


upvote
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What condition causes TrumpIsPresidentException :) ? – Vivek Mishra
3 upvote
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@VivekMishra When a wall is built – Ab_

In below showToast() method you have to pass another parameter for context or application context by doing so you can try it.

  public void showToast(String error, Context applicationContext){
        LayoutInflater inflater = getLayoutInflater();
        View view = inflater.inflate(R.layout.custom_toast, (ViewGroup)      
        findViewById(R.id.toast_root));
        TextView text = (TextView) findViewById(R.id.toast_error);
        text.setText(error);
        Toast toast = new Toast(applicationContext);
        toast.setGravity(Gravity.TOP | Gravity.FILL_HORIZONTAL, 0, 0);
        toast.setDuration(Toast.LENGTH_SHORT);
        toast.setView(view);
        toast.show();
}

This popup shows only when you get a fatal exception in your code which stops the execution of the app. It could be any exception NullPointerException, OutOfMemoryException etc.

Best way to check is through Logcat if you are still developing the app in Android studio which is quick way to read stack trace and check the cause of the app.

If your app is already live, then you can not use logcat. So, for that you can implement Crashlytics to provide you bug reports of any exception that occurs.

If your app for some reason crashes without good stacktrace. Try debug it from first line, and go line by line until crash. Then you will have answer, which line is causing you trouble. Proably you could then wrapp it into try catch block and print error output.

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