Save android logcat in a file on Android device

Question

I want to write Android logcat in a file on my device. To do that, I used the following code

protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);

    if(isExternalStorageWritable()){
        File appDirectory = new File(Environment.getExternalStorageDirectory()+ "/MyAppfolder");
        File logDirectory = new File(appDirectory + "/log");
        File logFile = new File(logDirectory, "logcat"+System.currentTimeMillis()+".txt");

        if(!appDirectory.exists()){
            appDirectory.mkdir();
        }

        if(!logDirectory.exists()){
            logDirectory.mkdir();
        }

        if(!logFile.exists()){
            try {
                logFile.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        try{
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                if(checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
                    Process process = Runtime.getRuntime().exec("logcat -f "+logFile);
                }
            }
        }
        catch (IOException e){
            e.printStackTrace();
        }
    }
    else if (isExternalStorageReadable()){
        Log.i(TAG, "ONLY READABLE");
    }
    else{
        Log.i(TAG, "NOT ACCESSIBLE");
    }}

    public boolean isExternalStorageReadable(){

    String state = Environment.getExternalStorageState();
    if(Environment.MEDIA_MOUNTED.equals(state) || Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)){
        return true;
    }
    return false;
}
   public boolean isExternalStorageWritable(){

    String state = Environment.getExternalStorageState();
    if(Environment.MEDIA_MOUNTED.equals(state)){
        return true;
    }
    return false;
}

And I added the permissions in AndroidManifest.xml

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

The folders and the file were created, but the file is always empty. How can I improve the code so the logcat will be written in the file.

Logcat will not be store in file if you will run your app in older device than marshmallow — Chirag, Jul 19 '17 at 09:07

score 2 · Accepted Answer · answered Jul 19 '17 at 11:48

if(checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);

}
else{
Process process = Runtime.getRuntime().exec("logcat -f "+logFile);
}

Your code is working perfectly may be, by mistake, You had written ask for permission & make log file both together

score 0 · Answer 2 · answered Jul 19 '17 at 09:22

0

Maybe you are not writing the log to the file. You are missing this method.

 /* Checks if external storage is available for read and write */
public boolean isExternalStorageWritable() {
    String state = Environment.getExternalStorageState();
    if ( Environment.MEDIA_MOUNTED.equals( state ) ) {
        return true;
    }
    return false;
}

Your took code from the solution of this question Stack overflow question. Check it out.

answered Jul 19 '17 at 09:22

Mohammed Farhan

1,120
8
14

Yes, i took the solution from the question you mentionned. I had the function in my code – minouch3900 Jul 19 '17 at 09:24
try giving permission to your app in device `setting>select your app>permissions>switch all the permission`. Am not sure but give a try. – Mohammed Farhan Jul 19 '17 at 09:30

score 0 · Answer 3 · answered Jul 19 '17 at 10:34

It's my pleasure to answer your question.

In my project,I use this to solve the problem.

1.add this class

public class LogcatHelper {

private static LogcatHelper INSTANCE = null;
private static String PATH_LOGCAT;
private LogDumper mLogDumper = null;
private int mPId;

/**
 * init data
 */
public void init(Context context) {
    if (Environment.getExternalStorageState().equals(
            Environment.MEDIA_MOUNTED)) {// sd first
        PATH_LOGCAT = Environment.getExternalStorageDirectory()
                .getAbsolutePath() + File.separator + "logcat";
    } else {
        PATH_LOGCAT = context.getFilesDir().getAbsolutePath()
                + File.separator + "logcat";
    }
    File file = new File(PATH_LOGCAT);
    if (!file.exists()) {
        file.mkdirs();
    }
}

public static LogcatHelper getInstance(Context context) {
    if (INSTANCE == null) {
        INSTANCE = new LogcatHelper(context);
    }
    return INSTANCE;
}

private LogcatHelper(Context context) {
    init(context);
    mPId = android.os.Process.myPid();
}

public void start() {
    if (mLogDumper == null)
        mLogDumper = new LogDumper(String.valueOf(mPId), PATH_LOGCAT);
    mLogDumper.start();
}

public void stop() {
    if (mLogDumper != null) {
        mLogDumper.stopLogs();
        mLogDumper = null;
    }
}

private class LogDumper extends Thread {

    private Process logcatProc;
    private BufferedReader mReader = null;
    private boolean mRunning = true;
    String cmds = null;
    private String mPID;
    private FileOutputStream out = null;

    public LogDumper(String pid, String dir) {
        mPID = pid;
        try {
            out = new FileOutputStream(new File(dir, "logcat"
                    + getFileName() + ".log"));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        /**
         *
         * Level：*:v , *:d , *:w , *:e , *:f , *:s
         *
         *
         * */

        // cmds = "logcat *:e *:w | grep \"(" + mPID + ")\""; // print e level and ilevel info
        // cmds = "logcat  | grep \"(" + mPID + ")\"";// print all
        // cmds = "logcat -s way";// print filter info
        cmds = "logcat *:e *:i | grep \"(" + mPID + ")\"";

    }

    public void stopLogs() {
        mRunning = false;
    }

    @Override
    public void run() {
        try {
            logcatProc = Runtime.getRuntime().exec(cmds);
            mReader = new BufferedReader(new InputStreamReader(
                    logcatProc.getInputStream()), 1024);
            String line = null;
            while (mRunning && (line = mReader.readLine()) != null) {
                if (!mRunning) {
                    break;
                }
                if (line.length() == 0) {
                    continue;
                }
                if (out != null && line.contains(mPID)) {
                    out.write((getDateEN() + "  " + line + "\n")
                            .getBytes());
                }
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (logcatProc != null) {
                logcatProc.destroy();
                logcatProc = null;
            }
            if (mReader != null) {
                try {
                    mReader.close();
                    mReader = null;
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                out = null;
            }

        }

    }

}

public static String getFileName() {
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
    String date = format.format(new Date(System.currentTimeMillis()));
    return date;
}

public static String getDateEN() {
    SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    String date1 = format1.format(new Date(System.currentTimeMillis()));
    return date1;
}

}

add code in the Application class

LogcatHelper.getInstance((getApplicationContext())).start();

3.add permissions in the Application class

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if(checkSelfPermission(android.Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
                Process process = Runtime.getRuntime().exec("logcat -f "+logFile);
            }
        }

I hope I can help you.

Thank you for your help. Your answer fixed my problem. – minouch3900 Jul 19 '17 at 11:24 — minouch3900, Jul 19 '17 at 11:24

Save android logcat in a file on Android device

3 Answers3