Develop Reference

app is not working after it's been terminated by app switcher

I have developed react-native android app. when i opened the app for the first time everything is ok and working as expected. Then i terminated my app by using app switcher then opened app once again. This time one white blank screen came and nothing happens from there. I have a console log in constructor in root file if the app and i didn't find this log in studio when i run the app. So, it's clear that constructor hasn't been called and this is where where i got struct.
Since I am not android developer I don't know how to debug this issue. Can someone help me to solve this?
Edit: This is happening only in release mode. Debug mode is working fine
Thank You.

Move console.log from constructor to componentDidMount.
Constructer is not called opening by switcher.

Android Studio, logcat cleans after app closes

I'm having a problem with my logcat since update 1.2 Beta for Android Studio. When I run my app it logs everything like it normally did, then I get at the point where my app crashes with the app saying: unfortunately, Game has stopped.
After a few seconds android closes that message. When that happens my logcat also gets fully cleared meaning that I barely get anytime to read the error. I did found some info about a buffer, but it seems that Android Studio doesn't have the option to increase it besides the fact that I doubt that being the problem.
Something that may be useful is that after it clears and stuff the process changes to Android.process.core and the message I get in my logcat is:
04-13 10:28:13.394 12259-12265/android.process.acore D/dalvikvm﹕
Debugger has detached; object registry had 1 entries
Edit: I did read about breakpoints, so disabled focus application on breakpoints in Settings-build, execution, deployment-debugger but it didn't have any effect.

I had the same issue, but looks more like a feature than a bug:
In AndroidStudio, the default setting for the Logcat window seems to be "Show only selected Application" (top right corner of the Logcat window)... which is looking at the log of the selected process (your current launch by default). So when your app crashes during testing, that process is gone, so the filter clears the log.
Instead, select "Edit Filter Configuration..." and set up a filter for your app, eg:
FilterName: MyApp
PackageName: com.example.myapp (<< replace with your app's package name)
...and then select that filter for future runs. This should keep the log there for you, even after the app crashes.

Switch "Show only selected application" to "No filters". This way, you can see logcat output from a process even when that process isn't running.
The downside is that your logcat will be filled with more spam from other processes.

In case of crash see the Run tab at the bottom of IDE.
You can see the crash reason in this part (even in logcat clean case).
Note: If the above trick not works try to produce a crash and immediately disconnect the mobile cable (if you use the real device for the test). you can see the error before it cleaned.
Update: If also above trick not works, try to attach and detach phone and hopefully problem solved.
Update2: If again not work, try to Invalidate catches and Restart then start debugging again.
Update3: As The last way, try to remove the app and install it again then start debugging (if you do not lose that condition you want to test)

My App was crashing and restarting. I also had some problems on reading the logcat to know what was happening. I then noticed that in the drop down menu, next to the Device dropdown it had something like "com.mypackage.myapp ('some number')" and when my app crashed there was another option that said "com.mypackage.myapp ('some number') [DEAD]". If you select the "Dead" option, it will show you the logcat of the previous instance.

Might be very late to the party but I had the same problem and solved like this:
In logcat window, top right corner drop-down menu select Edit filter configuration, on the next menu, introduce Filter name and your Package name.
Done, for me it keeps logs visible after crashing.

In Android Studio 2+
Click Run
Click Edit Configurations
In the Run/Debug Configurations window select the Miscellaneous tab
Make sure the Clear log before launch checkbox is not checked

The filter clears the log once the app gets crashed. So select "Edit Filter Configuration" and create your own custom filter with filter name. This will save the log with informations even when the app is crahed.

I'm Working with Android Studio 4.0
enter image description here
Go to Edit Configuration of your app.
Go to Miscellaneous Tab
Uncheck the field Clear log before launch.
Press OK.
It'll work..

i have faced the same issue and this is the solution :-
1- Tools --> Android --> Enable ADB Integration.
and now you can see the logcat and the crashes as normal

It is 2018 and this can still happen. Close Android Studio and reopen.

7 years later ...
I still have same issue on AS ArcticFox and nothing helps.
But I have found one workaround.
make sure this is enabled:
Then you can see your logs regardless the app is alive or not or device is connected or not. Which is great!

Still, sometimes I get this problem although some solutions work here such as restarting android studio it takes time.
Here I found how to get error message without restarting the studio
Launch the app
Be on run tab before you make your reproduce crash
Click on the content of run tab as soon as crash occurs (if you don't click on content you will lose error report)

This bug seems to be fixed with the new release of Android Studio version 1.2.2

I ran into the same problem and none of the answers could help me, until I realized my app was causing an OutOfMemoryException. That's a probable root cause as well.

Get crash information when debugger is not attached?

I'm developing an app using Android Studio. Now I'm facing a bug where the app crashes when I do the following:
Press the home button.
Use the device for some 10 minutes (i.e. wait).
Run the app again. Crash!
There is no easier way to reproduce the crash (nothing in onResume). As you can imagine, this is kind of hard to debug. In an ideal world, the OS (Android 5.0) would let me send a bug report to myself. The app is not published yet, so I don't see how I could get hold of the crash dump. Is it saved somewhere on the device?
I did try to debug the app from Developer Options, using the wait for debugger setting and then attaching to the process from within Android Studio. This, however, seems to make the bug go away. (The app is probably restarted.)
Q: How do I find the cause of the crash given these circumstances?

My intuition tells me that you are using some 'static' variables/fields in your application.
When your app goes to background and it is not used, system could drop process (because of memory management) of this application from memory. When you come back, Application object and all application proces in system is recreated, so all static variables are cleared/reinitialized.
Am i right?

Try looking into your logcat and if that is not an option for you. try some crash analytic like the following.
https://mint.splunk.com/
Integrate it in your app just with a single line and whenever your app get crashed you will receive a mail of your crash logs..
it will easily help you to determine your crash scenario..
And just out of curiosity are you using any singlton class in your Activity.?

I found the crash using adb as described here. Never realized that logcat keeps logs from previous executions. Nice!

Android device monitor crashing -- possibly due to Eclipse

Here's an odd issue I can't seem to find any information on.
I'm working on an Android app with a friend who uses Eclipse -- I use Ant and the Android command-line tools. Sometimes when I checkout code that was written by him and the project.properties file gets pulled into my local workspace, I'll have to change the path to the libraries back to where they're at on my machine, as it gets automatically set for him via Eclipse. This may be of use to know in light of what just started happening when I try to launch 'monitor' as I've always done; I get this error dialog box that pops up and says: An error has occurred, please see the logfile: /home/user/.android/monitor-workspace/.metadata/.log
So I did. It was, after I'd tried to launch monitor several times to no avail, a really long logcat-like file of Java traces. I cleared them out, thinking that perhaps it had run over its own max size for internal monitor data, but that didn't stop it crashing. A new set of errors just gets appended.
This is the first time this has ever happened, and unlike essentially every other Android problem I've had, I can't seem to find any existing information on it. The device monitor now seems to want to be integrated into Eclipse. I don't use Eclipse so I'm not sure how the monitor runs within it, or whether I'm correct in assuming that some configuration file somewhere needs to have a line changed (or whatever).
Here's the content of the logfile:
http://pastebin.com/JitCWrGg
Could anyone lend a word of advice?
Many thanks!

Android Emulator Debugging, Code will not Update

I'm having a troubling problem testing some code for and Android app. My app has two parts, and activity where the user changes some settings, and a broadcast receiver that responds to SMS messages, both in the same package.
Here's the problem, I first implemented some simple code to test out the broadcast receiver and the activity, and both worked fine. But then as I tried to refine the code, I noticed the emulator wasn't picking up any of my changes. Event went so far as to uninstall the app from the emulator and try again, no luck. Then I added some extra Toast popups to my receiver, nothing, still running the old code. I know its running the old code because its sending out an SMS using a string constant that is no longer in the current code, so it should be impossible that it respond with that value.
Here's the kicker that has me confused. For fun I made a change to my activity. Ran the project from Eclipse and that change showed up! Tried to test the receiver code again, runs the old code that doesn't even exist anymore!!
How in the world can half the package update, and the other half not?
Can anyone help me out 'cause I'm about ready to lose my mind.

I had a similar problem. Changes made to classes imported from another project didn't get picked up by eclipse, but those made to classes in the current android project were.
Making a change to the current android project (inserting a blank line and deleting it) seemed to make eclipse pick up all the changes made and upload the app to the emulator.

I had this problem too, Now I found a working solution. Just follow these steps:
Run your project normally.
When emulator started, run your project again (DO NOT close the first emulator)
Then the updated application will be uploaded into emulator

I can't really be sure what happened but creating an new emulator image appeared to solve the issue.

I don't know why it happens but it's a problem I have all the time.
What I typically do is
Close the emulator
Close Eclipse
Reopen Eclipse
Clean the projects (in Eclipse, select Project -> Clean... -> Clean all projects)
Rerun the emulator
Annoying as hell but seems to work for me.

I'm having this problem too. It mostly happens when errors are entered into the code. The strange thing is if I go back to the original code, Eclipse doesn't revert to the original code. One thing that seems to help is to temporary delete the contents of a file, save, and rebuild, and then enter the contents back into the file, save, and rebuild.
How is one supposed to debug in such an environment?