How to get Android crash logs?

Question

If your app is being downloaded by other people and crashing on remote devices, you may want to look into an Android error reporting library (referenced in this SO post). If it's just on your own local device, you can use LogCat. Even if the device wasn't connected to a host machine when the crash occurred, connecting the device and issuing an adb logcat command will download the entire logcat history (at least to the extent that it is buffered which is usually a loooot of log data, it's just not infinite). Do either of those options answer your question? If not can you attempt to clarify what you're looking for a bit more?

The way to do this is to implement the Thread.UncaughtExceptionHandler interface and pass it to Thread.setDefaultUncaughtExceptionHandler() at the beginning of your Activity's onCreate(). Here is the implementation class TopExceptionHandler.

public class TopExceptionHandler implements Thread.UncaughtExceptionHandler {
    private Thread.UncaughtExceptionHandler defaultUEH;
    private Activity app = null;

    public TopExceptionHandler(Activity app) {
        this.defaultUEH = Thread.getDefaultUncaughtExceptionHandler();
        this.app = app;
    }

    public void uncaughtException(Thread t, Throwable e) {
        StackTraceElement[] arr = e.getStackTrace();
        String report = e.toString()+"\n\n";
        report += "--------- Stack trace ---------\n\n";
        for (int i=0; i<arr.length; i++) {
            report += "    "+arr[i].toString()+"\n";
        }
        report += "-------------------------------\n\n";

        // If the exception was thrown in a background thread inside
        // AsyncTask, then the actual exception can be found with getCause

        report += "--------- Cause ---------\n\n";
        Throwable cause = e.getCause();
        if(cause != null) {
            report += cause.toString() + "\n\n";
            arr = cause.getStackTrace();
            for (int i=0; i<arr.length; i++) {
                report += "    "+arr[i].toString()+"\n";
            }
        }
        report += "-------------------------------\n\n";

        try {
            FileOutputStream trace = app.openFileOutput("stack.trace", 
                                                        Context.MODE_PRIVATE);
            trace.write(report.getBytes());
            trace.close();
        } catch(IOException ioe) {
        // ...
        }

        defaultUEH.uncaughtException(t, e);
    }
}

Note We let the Android framework's defaultUEH to handle it.

At the top of your Activity register an instance of above class like this:

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

Thread.setDefaultUncaughtExceptionHandler(new TopExceptionHandler(this));
...

This handler saves the trace in a file. When ReaderScope restarts next time, it detects the file and prompts the user if he/she wants to email it to the developer.

To Email the Stack Trace, execute following code to pack it in an email.

try {
    BufferedReader reader = new BufferedReader(
        new InputStreamReader(ReaderScopeActivity.this.openFileInput("stack.trace")));
    while((line = reader.readLine()) != null) {
        trace += line+"\n";
    }
} catch(FileNotFoundException fnfe) {
    // ...
} catch(IOException ioe) {
    // ...
}

Intent sendIntent = new Intent(Intent.ACTION_SEND);
String subject = "Error report";
String body = "Mail this to [email protected]: " + "\n" + trace + "\n";

sendIntent.putExtra(Intent.EXTRA_EMAIL, new String[] {"[email protected]"});
sendIntent.putExtra(Intent.EXTRA_TEXT, body);
sendIntent.putExtra(Intent.EXTRA_SUBJECT, subject);
sendIntent.setType("message/rfc822");

ReaderScopeActivity.this.startActivity(Intent.createChooser(sendIntent, "Title:"));

ReaderScopeActivity.this.deleteFile("stack.trace");

Or you can also use ACRA Error Reporting System.Just Include the ACRA.jar in your project libs and use the below code snippet before your launcher activity class declaration

@ReportsCrashes(formKey = "", mailTo = "[email protected];[email protected]", mode = ReportingInteractionMode.SILENT) 

or You can try this from console:-

adb logcat -b crash 

You can try this from the console:

adb logcat --buffer=crash 

More info on this option:

adb logcat --help

...

  -b <buffer>, --buffer=<buffer>         Request alternate ring buffer, 'main',
                  'system', 'radio', 'events', 'crash', 'default' or 'all'.
                  Multiple -b parameters or comma separated list of buffers are
                  allowed. Buffers interleaved. Default -b main,system,crash.

This is from http://www.herongyang.com/Android/Debug-adb-logcat-Command-Debugging.html

You can use adb:

adb logcat AndroidRuntime:E *:S

If you're using Eclipse, make sure you use debug and not run. Make sure you are in the debug perspective (top right) You may have to hit 'Resume' (F8) a few times for the log to print. The crash log will be in the Logcat window at the bottom- double click for fullscreen and make sure you scroll to the bottom. You'll see red text for errors, the crash trace will be something like

09-04 21:35:15.228: ERROR/AndroidRuntime(778): Uncaught handler: thread main exiting due to uncaught exception
09-04 21:35:15.397: ERROR/AndroidRuntime(778): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dazlious.android.helloworld/com.dazlious.android.helloworld.main}: java.lang.ArrayIndexOutOfBoundsException
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2268) 
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2284)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.app.ActivityThread.access$1800(ActivityThread.java:112)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1692)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.os.Handler.dispatchMessage(Handler.java:99)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.os.Looper.loop(Looper.java:123)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.app.ActivityThread.main(ActivityThread.java:3948)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at java.lang.reflect.Method.invokeNative(Native Method)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at java.lang.reflect.Method.invoke(Method.java:521)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at dalvik.system.NativeStart.main(Native Method)
09-04 21:35:15.397: ERROR/AndroidRuntime(778): Caused by: java.lang.ArrayIndexOutOfBoundsException
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at com.example.android.helloworld.main.onCreate(main.java:13)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2231)
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     ... 11 more

The important parts for this one are

09-04 21:35:15.397: ERROR/AndroidRuntime(778): Caused by: java.lang.ArrayIndexOutOfBoundsException
09-04 21:35:15.397: ERROR/AndroidRuntime(778):     at com.example.android.helloworld.main.onCreate(main.java:13)

those tell us it was an array out of bounds exception on on line 13 of main.java in the onCrate method.

You can use Apphance. This is a cross-platform service (now mainly Android, iOS with other platforms on their way) which allows to debug remotely any mobile device (Android, iOS now - others under development). It's much more than just a crashlog, in fact it is much more: logging, reporting of problems by testers, crashlogs. It takes about 5 minutes to integrate. Currently you can request for access to closed beta.

Disclaimer: I am CTO of Polidea, a company behind Apphance and co-creator of it.

Update: Apphance is no longer closed beta! Update 2: Apphance is available as part of http://applause.com offering