Lightweight logging library enabling flexible log management with console and file logging, SLF4J integration, custom loggers, and efficient handling of expensive computations across various platforms.
Lightweight logging library for Kotlin/Multiplatform. Supports Android, iOS, JavaScript and plain JVM environments.
Artifacts are published to Maven Central:
repositories {
mavenCentral()
}
dependencies {
implementation("de.peilicke.sascha:log4k:1.6.0")
}
Logging messages is straightforward, the Log object provides the usual functions you'd expect:
// Log to your heart's content
Log.verbose("FYI")
Log.debug("Debugging ${foo.bar}")
Log.info("Nice to know", tag = "SomeClass")
Log.warn("Warning about $stuff ...")
Log.error("Oops!")
Log.assert("Something went wrong!", throwable)
Or, if you prefer:
Log.verbose { "FYI" }
Log.debug { "Debugging ${foo.bar}" }
Log.info(tag = "SomeClass") { "Nice to know" }
Log.warn { "Warning about $stuff ..." }
Log.error { "Oops!" }
Log.assert(throwable = Exception("Ouch!")) { "Something went wrong!" }
The log output includes the function name and line and pretty-prints exceptions on all supported platforms:
I/Application.onCreate: Log4K rocks!
In case you want to log Any Kotlin class instance or object:
val map = mapOf("Hello" to "World")
map.logged()
The above example logs {Hello=World} with the tag SingletonMap with the log level Debug.
Sometimes, the log output involves a heavy computation that is not always necessary. For example, if the global log
level is set to Info or above, the following text would not appear in any log output:
Log.debug("Some ${veryHeavyStuff()}")
However, the function veryHeavyStuff() will be executed regardless. To avoid this, use:
Log.debug { "Some ${veryHeavyStuff()}" }
To only output messages with log-level info and above, you can configure the console logger in your Application class:
class MyApplication : Application() {
override fun onCreate() {
super.onCreate()
Log.loggers.forEach {
if (!BuildConfig.DEBUG) {
it.minimumLogLevel = Log.Level.Info
}
}
}
}
By default, the library only logs to the current platform's console. Additionally or instead, add one or multiple file loggers:
// Log with daily rotation and keep five log files at max:
Log.loggers += FileLogger(rotate = Rotate.Daily, limit = Limit.Files(max = 5))
// Log to a custom path and rotate every 1000 lines written:
Log.loggers += FileLogger(rotate = Rotate.After(lines = 1000), logPath = "myLogPath")
// Log with sensible defaults (daily, keep 10 files)
Log.loggers += FileLogger()
// One huge eternal log file:
Log.loggers += FileLogger(rotate = Rotate.Never, limit = Limit.Not)
The library provides a cross-platform ConsoleLogger by default. Custom loggers can easily be added. For instance, to
send only ERROR and ASSERT messages to Crashlytics in production builds, you could do the following:
Ktor supports providing a custom logger:
import io.ktor.client.*
import io.ktor.client.engine.cio.*
import io.ktor.client.plugins.logging.*
import saschpe.log4k.Log
val httpClient = HttpClient(CIO) {
install(Logging) {
level = LogLevel.ALL
logger = object : Logger {
override fun log(message: String) = Log.info { message }
}
}
}
Copyright 2019 Sascha Peilicke
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance the License.
You may obtain a copy of the License at
http:
Unless applicable law agreed to writing, software
distributed under the License distributed an BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express implied.
See the License the specific language governing permissions
limitations under the License.
Surfaced from shared tags and platforms — no rankings paid for.
class MyApplication : Application() {
override fun onCreate() {
super.onCreate()
Log.loggers.clear() // Remove default loggers
Log.loggers += when {
BuildConfig.DEBUG -> ConsoleLogger()
else -> CrashlyticsLogger()
}
}
private class CrashlyticsLogger : Logger() {
override fun print(level: Log.Level, tag: String, message: String?, throwable: Throwable?) {
val priority = when (level) {
Log.Level.Verbose -> VERBOSE
Log.Level.Debug -> DEBUG
Log.Level.Info -> INFO
Log.Level.Warning -> WARN
Log.Level.Error -> ERROR
Log.Level.Assert -> ASSERT
}
if (priority >= ERROR) {
FirebaseCrashlytics.getInstance().log("$priority $tag $message")
throwable?.let { FirebaseCrashlytics.getInstance().recordException(it) }
}
}
}
}