Kotlin logger - log to a file

Question

class LogToFile(context: Context) {
        companion object: KLogging()
        val formatter = SimpleFormatter()

        // val logger = LoggerFactory.getLogger("MyLog") **WITH THIS LINE...**

        val logger = Logger.getLogger("MyLog") //this line WORKS
        val dest = context.applicationContext.getExternalFilesDir(null);
        val fh = FileHandler(dest.path.plus(File.pathSeparator).plus("data.txt"))

        init {

            //..THIS LINE DOESN'T WORK (NO addHandler is there some ekvivalent for the LoggerFactory?)//

            logger.addHandler(fh)
            fh.formatter = formatter
        }


        fun write(logString: String) {

            try {

                logger.info(logString)

            } catch (e: SecurityException) {
                e.printStackTrace()
            } catch (e: IOException) {
                e.printStackTrace()
            }
        }
}

**This is a functioning code I have, which takes a log and writes it into a file.

In the past few days, I haven't been able to find a way, how to do the same thing using KotlinLogger.

I am trying to write all the logs into a file.

I am a coding beginner, so I hope the question is written well enough. If it isn't I will complete it.

I have been googling how to do it and I found nothing, so I hope it is possible.

The Logger that's working is 'java.util.logging.Logger' the one I want to use is 'mu.KLogging' (or possibly 'org.slf4j.LoggerFactory')

UPDATE: I found this: https://github.com/tony19/logback-android/wiki currently implementing:

 implementation 'io.github.microutils:kotlin-logging:1.4.9'
    implementation 'org.slf4j:slf4j-api:1.7.25'
    compile 'com.github.tony19:logback-android-core:1.1.1-6'
    compile('com.github.tony19:logback-android-classic:1.1.1-6') {
        // workaround issue #73
        exclude group: 'com.google.android', module: 'android'

simple log into log cat works now. Still working on writing the logs into a file. **

what is the full package of `Logger`? kotlin-logging is using slf4j, slf4j Logger does not have addHandler. in log4j,logback for example it can be configured with a property file. here is a logback example: https://examples.javacodegeeks.com/enterprise-java/logback/logback-configuration-example/ — oshai, Jan 29 '18 at 10:14
In the one, that's working, the package is java.util.logging.Logger the one I want to use is mu.KLogging (or possibly org.slf4j.LoggerFactory) I'm going through the slf4j documentation now and trying to find how to do it. — Sophie M, Jan 29 '18 at 10:46
ok, note sl4j and kotlin-logging are wrappers around java-util-logging, so the api is a bit different. The de-facto standard, in this case, is logback instead of java-util-logging — oshai, Jan 29 '18 at 11:48
I am going through the logback.xml it seems to be a good solution but I haven't figured it out yet. Thak you very much! I will post it as soon as I figure it out. (if I manage to do it) — Sophie M, Jan 29 '18 at 12:34
If this is an android app you can take a look here for an example: https://github.com/MicroUtils/kotlin-logging-example-android — oshai, Jan 29 '18 at 12:51

Sophie M · Accepted Answer · 2018-05-10T13:14:10.790

So, I managed to log into the logcat and a file. Since I never found this problem solved anywhere else, I am posting here in case someone needs it sometime.

I compiled these in my gradle file:

dependencies {
    implementation 'io.github.microutils:kotlin-logging:1.4.9'


implementation 'com.github.tony19:logback-android-core:1.1.1-6'
implementation('com.github.tony19:logback-android-classic:1.1.1-6') {
    // workaround issue #73
    exclude group: 'com.google.android', module: 'android'
}

implementation 'org.slf4j:slf4j-api:1.7.25'

implementation 'log4j:log4j:1.2.17'

I used a companion object in the logging class:

import mu.KLogging

class LogToFile(context: Context) {

    companion object: KLogging()

fun write(){
logger.info("Hello World")}
}

and made a logback.xml configurations file:

<property name="USER_HOME" value='file_path'/>

<appender name="LOG" class="ch.qos.logback.core.FileAppender">
<!--append to file-->
    <file>
    ${USER_HOME}/myApp.log
</file>
    <encoder>
        <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
</appender>

<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <!-- encoders are assigned the type
         ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
    <encoder>
        <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
</appender>

<root level="debug">
    <appender-ref ref="LOG"/>
    <appender-ref ref="STDOUT" />
</root>

so it currently writes into a file and a logcat and everything works just fine.

src -> main -> assets link here: https://stackoverflow.com/questions/18302603/where-do-i-place-the-assets-folder-in-android-studio — Sophie M, Jul 09 '18 at 09:37

Kotlin logger - log to a file

1 Answers1