Android saving logs on every run for crash report [duplicate]

Question

I'm currently developing an android app. I noticed a very rare error which leeds to a crash of my app. Unfortunately, I had my smartphone never connected to my pc when it occured. So, is there a way to automatically save all logs (and especially the thrown runtimeexceptions) to a file when my app starts, so that I can copy this file to my pc and analyse the error? The file should be overwritten on every start of my app, so that it contains only the logs of the last run... How can I achieve that?

regards

Thracophrygian

Answer 1

You can find help by following this link Writing crash reports into device sd card

You don't need to add external library.

import com.wordpress.doandroid.Training.R;

import android.app.Activity;
import android.os.Bundle;

public class CaptureExceptionActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Sets the default uncaught exception handler. This handler is invoked
        // in case any Thread dies due to an unhandled exception.
        Thread.setDefaultUncaughtExceptionHandler(new CustomizedExceptionHandler(
            "/mnt/sdcard/"));

        String nullString = null;
        System.out.println(nullString.toString());
        setContentView(R.layout.main);
    }
}

And the Handler implementation

import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.Thread.UncaughtExceptionHandler;
import java.text.SimpleDateFormat;
import java.util.Date;

import android.os.Environment;
import android.util.Log;

public class CustomizedExceptionHandler implements UncaughtExceptionHandler {

    private UncaughtExceptionHandler defaultUEH;
    private String localPath;
    public CustomizedExceptionHandler(String localPath) {
        this.localPath = localPath;
        //Getting the the default exception handler
        //that's executed when uncaught exception terminates a thread
        this.defaultUEH = Thread.getDefaultUncaughtExceptionHandler();
    }

    public void uncaughtException(Thread t, Throwable e) {

        //Write a printable representation of this Throwable
        //The StringWriter gives the lock used to synchronize access to this writer.
        final Writer stringBuffSync = new StringWriter();
        final PrintWriter printWriter = new PrintWriter(stringBuffSync);
        e.printStackTrace(printWriter);
        String stacktrace = stringBuffSync.toString();
        printWriter.close();

        if (localPath != null) {
            writeToFile(stacktrace);
        }

        //Used only to prevent from any code getting executed.
        // Not needed in this example
        defaultUEH.uncaughtException(t, e);
    }

    private void writeToFile(String currentStacktrace) {
        try {

            //Gets the Android external storage directory & Create new folder Crash_Reports
            File dir = new File(Environment.getExternalStorageDirectory(),
                "Crash_Reports");
            if (!dir.exists()) {
                dir.mkdirs();
            }

            SimpleDateFormat dateFormat = new SimpleDateFormat(
                "yyyy_MM_dd_HH_mm_ss");
            Date date = new Date();
            String filename = dateFormat.format(date) + ".STACKTRACE";

            // Write the file into the folder
            File reportFile = new File(dir, filename);
            FileWriter fileWriter = new FileWriter(reportFile);
            fileWriter.append(currentStacktrace);
            fileWriter.flush();
            fileWriter.close();
        } catch (Exception e) {
            Log.e("ExceptionHandler", e.getMessage());
        }
    }

}

Don't forget to add this permission in the manifest WRITE_EXTERNAL_STORAGE

Talus

Awesome! But what is the defaultUEH, which is Used only to prevent from any code getting executed, and Not needed in this example? So where is it needed? – Coe

You can put this statement as comment to know the effect. Normally, without this statement, your app will not crash. With this statement, it will crash, however you get the stacktrace before. – Talus