Logging to a file on Android

Question

Is there any way of retrieving log messages from an Android handset.

I\'m building an application which uses the GPS of my HTC Hero. I can run and debug the applicat

Answer 1

Use slf4-android lib created by BrightInventions. It's simple implementation of slf4j api using android java.util.logging.*.

Features:

• logging to file out of the box
• logging to any other destination by LoggerConfiguration.configuration().addHandlerToLogger
• shake your device to send logs with screenshot via email
• really small, it tooks only ~55kB

slf4android is maintained mainly by @miensol.

Read more about slf4android on our blog:

• Introducing slf4android
• Integrate slf4android with Crashlytics

Answer 2

Based on @Greg B solution and @JPM question in the comment, I made this static method in a seperate class and each time you instanciate a new thread, call it.

package com.stackoverflow.

import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

import android.os.Environment;

public class UnhandledExceptionHandler {

    public static void setUndhandledException(Thread thread) {
        if (thread.getUncaughtExceptionHandler() == null) {
            Thread.currentThread().setUncaughtExceptionHandler(
                    new Thread.UncaughtExceptionHandler() {
                        @Override
                        public void uncaughtException(Thread thread,
                                Throwable ex) {

                            PrintWriter pw;
                            try {
                                pw = new PrintWriter(new FileWriter(Environment
                                        .getExternalStorageDirectory()
                                        + "/rt-networkandgps"
                                        + "/gpx/"
                                        + thread.getId() + ".log", true));
                                ex.printStackTrace(pw);
                                pw.flush();
                                pw.close();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }
                    });
        }

    }

}

Call it from anythread like this,

            UnhandledExceptionHandler.setUndhandledException(Thread.currentThread());

Answer 3

I tried both options above (microlog4android & android-logging-log4j) and they were a struggle to try to get working. Once they compiled fine then I would get Runtime java.lang.NoClassDefFoundError.

So then I stumbled on logback-android ... also found here http://logback.qos.ch/

It has much better instructions and I got it working in a couple hours.

This appears to be the best logging solution for Android.

Answer 4

You could use Thread.setUncaughtExceptionHandler() to catch the Exceptions.

Writing to SD Card is as simple as retrieving the directory for the card using Environment.getExternalStorageDirectory() and creating a file there.

File f = new File(Environment.getExternalStorageDirectory(),filename);

You will need to give you app the correct permission to write to the SD Card by adding this to your Manifest:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Answer 5

Log4j or slf4j can also be used as logging frameworks in Android together with logcat. See the project android-logging-log4j. Configuring logging to a (rotating) file(s) is very easy.

 static {
    final LogConfigurator logConfigurator = new LogConfigurator();

    logConfigurator.setFileName(Environment.getExternalStorageDirectory() + "myapp.log");
    logConfigurator.setRootLevel(Level.DEBUG);
    // Set log level of a specific logger
    logConfigurator.setLevel("org.apache", Level.ERROR);
    logConfigurator.configure();
}

Answer 6

You could take a look at microlog4android. They have a solution ready to log to a file.

https://github.com/johanlkarlsson/microlog4android