Using tags with Timber

kiri 2025-05-22 1 min read Permalink

The Android logging functions (the methods of the Log class) accept a tag argument that can be used to identify the source of the log message. It is common practice to use a constant to define this tag, like in the following example:

class Frobnicator {
    fun frobnicate() {
        Log.d(TAG, "Executing frobnicate")
    }

    fun fooBar() {
        Log.d(TAG, "Executing fooBar")
    }

    companion object {
        private val TAG: String = Frobnicator::class.simpleName!!
    }
}

Setting a tag can be achieved in Timber by using the tag() method, for instance:

Timber.tag(TAG).d("The medium is the massage")

Although please note that tag() returns a new Tree instance, hence the constant isn’t really needed and setting the tag can be shortened to returning the logger instance directly.

class DefaultFrobnicator : Frobnicator {
    // no need to define the tag separately
    private val log: Timber.Tree
        get() = Timber.tag(Frobnicator::class.simpleName!!)

    fun frobnicate() {
        log.d("Executing frobnicate")
    }

    fun fooBar() {
        log.d("Executing fooBar")
    }
}