Planting Timber logs the right way

September 1, 2021

Logging is among the essential things we do while developing android apps. Yet, as developers, we sometimes use the traditional log classes. These tend to be cumbersome.

Timber, which is a library created by Jake Wharton has made logging effortless.

This article will discuss the best practices in using Timber and planting the Timber trees.

Requirements

To tag along with this tutorial comfortably, you should:

Have a working android studio IDE.
Be able to create a project in Android Studio.
Have an understanding of Kotlin or Java.
Have some basic knowledge of the Logging class.

Objectives

By the end of this tutorial, you should be able to:

Know what is Timber.
Android logging with Timber.

Introduction

Logging is essential and is of much importance while developing android apps. We use logs for almost everything.

For instance, when debugging if-else conditions and when handling exceptions. Yet, as developers, we sometimes use the traditional log classes. These tend to be cumbersome and time-consuming.

Timber has made logging easily attainable and less code.

What is a Logcat?

From the official documentation, the logcat window in Android Studio displays system messages.

For example, when a garbage collection occurs, the logcat displays these messages in real-time. It also allows you to view older messages.

When your code throws an exception, the logcat displays a message. The exception contains an associated stack trace containing links to the line of code.

What are some of the traditional log class messages?

According to the official documentation, this class allows for the creation of log messages. These messages appear in the logcat. From the highest priority to the lowest (or, least verbose to the most). We should use the following:

Log.e(String, String) - display errors
Log.w(String, String) - display warnings
Log.i(String, String) -display information
Log.d(String, String) -displays debug information
Log.v(String, String) - for verbose

What is Timber?

Logging with the traditional class is cumbersome; that’s where Timber comes in.

In the official documentation, Timber is a logger with a small, extensible API. It provides utility on top of android’s standard Log class.

Timber also has several log messages:

Timber.i - for information
Timber.d - for debug information
Timber.v - for verbose
Timber.w and Timber.wtf - for warning

How it works.

You plant a tree by calling Timber.plant in your onCreate in your Application Class
Call the Timber from any class. Our class name is what we can use as the tag.

Now, how about we do some coding…

In this example, we’ll create an app that adds two numbers. Then we’ll log the answer.

Step 1: Create the project

We will kick off by creating a project. The image below will guide you into creating a project.

create_project

Step 2: Adding Timber dependency

After creating the project, we will add Timber's dependency to our app-level build Gradle.

//Timber dependency
implementation 'com.jakewharton.timber:timber:4.7.1'

adding dependency

Step 3: XML layouts

We will now create and design our layout.

Main Activity layout

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <EditText
        android:id="@+id/first_number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="Enter Number..."
        android:inputType="number"
        android:textColor="#000000"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.19999999" />

    <EditText
        android:id="@+id/second_number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="Enter Number..."
        android:inputType="number"
        android:textColor="#000000"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/first_number"
        app:layout_constraintVertical_bias="0.120000005" />

    <TextView
        android:id="@+id/answer"
        android:layout_width="0dp"
        android:layout_height="40dp"
        android:gravity="center"
        android:textColor="#000000"
        android:textSize="24sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/second_number" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:backgroundTint="#F4511E"
        android:text="Add"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toTopOf="@+id/answer"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/second_number" />
</androidx.constraintlayout.widget.ConstraintLayout>

Step 4: The Timber App Class

After creating the layout, we will write the code for our Application class of Timber creating a class in java

import android.app.Application;

import timber.log.Timber;

public class TimberDemoApp extends Application {

    @Override
    public void onCreate() {
        super.onCreate();

        Timber.plant(new Timber.DebugTree());
    }
}

creating a class in kotlin

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

class TimberDemoApp : Application() {

    override fun onCreate() {
        super.onCreate()

        Timber.plant(DebugTree())
    }
}

After creating the class, update your Manifest file with the name tag. Use your application class as the value as shown below: updating the manifest

Step 5: The code. (Main Activity)

In this step, we will write the code for the two-number-adder that we have designed above.

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import timber.log.Timber;

public class MainActivity extends AppCompatActivity {
    private Button button;
    private EditText num1, num2;
    private TextView answer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        button = findViewById(R.id.button);
        num1 = findViewById(R.id.first_number);
        num2 = findViewById(R.id.second_number);
        answer = findViewById(R.id.answer);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int first_number = Integer.parseInt(num1.getText().toString().trim());
                int second_number = Integer.parseInt(num2.getText().toString().trim());

                if (num1.getText().toString().isEmpty() || num2.getText().toString().isEmpty()){
                    num1.setError("Cannot be empty!!");

                }
                else{
                    int sum = first_number+second_number;
                    answer.setText(String.valueOf(sum));
                    Timber.v(answer.getText().toString());
                }
            }
        });
  }
}

Kotlin

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import timber.log.Timber

class MainActivity : AppCompatActivity() {

    private lateinit var button:Button
    private lateinit var num1:EditText
    private lateinit var num2:EditText
    private lateinit var answer:TextView

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        button = findViewById(R.id.button)
        num1 = findViewById(R.id.first_number)
        num2 = findViewById(R.id.second_number)
        answer = findViewById(R.id.answer)

        button.setOnClickListener {
            val first_number = num1.text.toString().trim { it <= ' ' }.toInt()
            val second_number = num2.text.toString().trim { it <= ' ' }.toInt()
            if (num1.text.toString().isEmpty() || num2.text.toString().isEmpty()) {
                num1.error = "Cannot be empty!!"
            } else {
                val sum = first_number + second_number
                answer.text = sum.toString()
                Timber.d(answer.text.toString())
            }
        }
    }
}

Timber Logcat

In the logcat, you will see such a line like this D/MainActivity: We did not specify the class name but timber placed one for us. That is the beauty of Timber.

Demonstration screens

Let’s run the application on a device or emulator. The logcat output should be as shown below.

log output in java

log output kotlin

Check out the entire Java project on GitHub. For Kotlin Github

Conclusion

That’s not all about Logging with Timber; keep exploring.

Implement logging using this amazing tool in your android applications and improve the readability of your application logs.

Resources

Peer Review Contributions by: Odhiambo Paul