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Android – print full exception backtrace to log

Posted by: admin March 11, 2020 Leave a comment

Questions:

I have a try/catch block that throws an exception and I would like to see information about the exception in the Android device log.

I read the log of the mobile device with this command from my development computer:

/home/dan/android-sdk-linux_x86/tools/adb shell logcat

I tried this first:

try {
    // code buggy code
} catch (Exception e)
{
    e.printStackTrace();
}

but that doesn’t print anything to the log. That’s a pity because it would have helped a lot.

The best I have achieved is:

try {
    // code buggy code
} catch (Exception e)
{
    Log.e("MYAPP", "exception: " + e.getMessage());             
    Log.e("MYAPP", "exception: " + e.toString());
}

Better than nothing but not very satisfying.

Do you know how to print the full backtrace to the log?

Thanks.

How to&Answers:
try {
    // code that might throw an exception
} catch (Exception e) {
    Log.e("MYAPP", "exception", e);
}

More Explicitly with Further Info

(Since this is the oldest question about this.)

The three-argument Android log methods will print the stack trace for an Exception that is provided as the third parameter. For example

Log.d(String tag, String msg, Throwable tr)

where tr is the Exception.

According to this comment those Log methods “use the getStackTraceString() method … behind the scenes” to do that.

Answer:

This helper function also works nice since Exception is also a Throwable.

    try{
        //bugtastic code here
    }
    catch (Exception e)
    {
         Log.e(TAG, "Exception: "+Log.getStackTraceString(e));
    }

Answer:

catch (Exception e) {
  ByteArrayOutputStream baos = new ByteArrayOutputStream();
  PrintStream stream = new PrintStream( baos );
  e.printStackTrace(stream);
  stream.flush();
  Log.e("MYAPP", new String( baos.toByteArray() );
}

Or… ya know… what EboMike said.

Answer:

public String getStackTrace(Exception e){
  StringWriter sw = new StringWriter();
  PrintWriter pw = new PrintWriter(sw);
  e.printStackTrace(pw);
  return sw.toString();
}

Answer:

e.printStackTrace() prints it to me. I don’t think you’re running the logcat correctly. Don’t run it in a shell, just run

/home/dan/android-sdk-linux_x86/tools/adb logcat

Answer:

The standard output and error output are directed to /dev/null by default so it is all lost. If you want to log this output then you need to follow the instructions “Viewing stdout and stderr” shown here

Answer:

try{
            ...
} catch (Exception e) {
     Log.e(e.getClass().getName(), e.getMessage(), e.getCause());
}

Answer:

In the context of Android, I had to cast the Exception to a String:

try {
    url = new URL(REGISTRATION_PATH);
    urlConnection = (HttpURLConnection) url.openConnection();
} catch(MalformedURLException e) {
    Log.i("MALFORMED URL", String.valueOf(e));
} catch(IOException e) {
    Log.i("IOException", String.valueOf(e));
}