How to customize Timber's log output format in Kotlin Android

How to customize Timber's log output format in Kotlin Android.

Timber is a popular logging library for Android that provides a simple and flexible way to log messages during the development and debugging process. By default, Timber uses a simple log output format. However, you can customize the log output format to suit your specific needs.

In this tutorial, we will explore how to customize Timber's log output format in Kotlin Android. We will cover the following steps:

1. Add Timber to your project
2. Create a custom Timber tree
3. Customize the log output format

1. Add Timber to your project

To get started, you need to add Timber to your project by adding the following dependency to your app-level build.gradle file:

implementation 'com.jakewharton.timber:timber:4.7.1'

After adding the dependency, sync your project to download the required files.

2. Create a custom Timber tree

Timber uses a concept called "Timber trees" to determine where and how log messages are handled. To customize the log output format, we need to create a custom Timber tree.

Create a new Kotlin class called CustomTimberTree and make it extend the Timber.Tree class. Override the log method to define how log messages should be handled.

import timber.log.Timber

class CustomTimberTree : Timber.Tree() {

    override fun log(priority: Int, tag: String?, message: String, t: Throwable?) {
        // Define custom log output format
        val logMessage = "[${getLogLevelString(priority)}] $tag: $message"
        
        // Handle log message
        // For example, you can send logs to a remote server, write to a file, etc.
    }

    // Helper method to get log level string
    private fun getLogLevelString(priority: Int): String {
        return when (priority) {
            Log.VERBOSE -> "VERBOSE"
            Log.DEBUG -> "DEBUG"
            Log.INFO -> "INFO"
            Log.WARN -> "WARN"
            Log.ERROR -> "ERROR"
            else -> "UNKNOWN"
        }
    }
}

3. Customize the log output format

To use the custom Timber tree and customize the log output format, you need to initialize Timber with your custom tree in the onCreate method of your application class or any other suitable place.

import android.app.Application
import timber.log.Timber

class MyApp : Application() {

    override fun onCreate() {
        super.onCreate()

        // Initialize Timber with custom tree
        Timber.plant(CustomTimberTree())

        // Now you can use Timber for logging
        Timber.d("Hello, Timber!")
    }
}

With the above code, every log message will be formatted using the custom log output format defined in the CustomTimberTree class.

You can further customize the log output format by modifying the logMessage variable in the log method of the CustomTimberTree class. For example, you can include additional information such as the current time, thread ID, or any other relevant data.

override fun log(priority: Int, tag: String?, message: String, t: Throwable?) {
    val currentTime = SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.getDefault()).format(Date())
    val logMessage = "[$currentTime] [${getLogLevelString(priority)}] $tag: $message"
    
    // Handle log message
}

You can also use different log output formats for different log levels or tags by adding conditions in the log method.

override fun log(priority: Int, tag: String?, message: String, t: Throwable?) {
    if (priority == Log.ERROR) {
        // Handle error log messages differently
    } else {
        // Handle other log messages
    }
}

Remember to remove any debug or development-specific logging code from your release builds to ensure that sensitive information is not logged.

That's it! You have successfully customized Timber's log output format in Kotlin Android. You can now use Timber for logging and have full control over the log message format.