Kotlin Logcat Not Showing Logs: Quick Fix

When developing Android apps in Kotlin, Logcat is an essential tool for debugging and tracking the behavior of your application in real time. However, sometimes developers face an issue where Logcat simply stops showing logs even though the app is running and logging commands are present in the code. This guide will walk you through the common causes and quick fixes to solve the Kotlin Logcat not showing logs problem.

Understanding the Problem

Logcat in Android Studio should display logs generated from your app using commands like Log.d(), Log.i(), or Log.e(). However, if you notice nothing appears, it could be due to:

• Incorrect Logcat filter settings
• Logs being filtered out by log level
• ProGuard or R8 removing log statements in release mode
• ADB connection issues
• App not running on the correct device instance
• Permission issues with the emulator or device

Quick Fixes

1. Check Logcat Filters

Ensure that the Logcat filter in Android Studio is set to show logs from your app’s process. Set the dropdown to your application package and choose the log level Verbose to display all logs.

2. Use Verbose Log Level

Logs at levels lower than the selected filter will not appear. For example, if your filter is set to Info, you will not see Log.d() messages. Change the filter to Verbose to catch everything.

3. Example Kotlin Code with Logs

Below is a simple Kotlin example that demonstrates proper logging. Make sure your log tag is consistent and easy to filter in Logcat.

import android.os.Bundle
import android.util.Log
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    companion object {
        private const val TAG = "MainActivity"
    }

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

        Log.v(TAG, "Verbose log: App started")
        Log.d(TAG, "Debug log: onCreate executed")
        Log.i(TAG, "Info log: Initialization complete")
        Log.w(TAG, "Warning log: Sample warning")
        Log.e(TAG, "Error log: Simulated error for testing")
    }
}

4. Ensure You Are in Debug Mode

In release builds, logging might be stripped by ProGuard or R8. Make sure you are running in debug mode while testing.

5. Disable Log Removal in ProGuard

If you need logs in release mode, add this rule in proguard-rules.pro:

-assumenosideeffects class android.util.Log {
    public static *** v(...);
    public static *** d(...);
    public static *** i(...);
    public static *** w(...);
    public static *** e(...);
}

6. Restart ADB and Android Studio

ADB glitches can cause Logcat to stop showing logs. Restart ADB with:

adb kill-server
adb start-server

Or restart Android Studio completely.

7. Check Device Connection

Ensure your device or emulator is properly connected. If using a physical device, enable USB debugging in Developer Options.

8. Clear Logcat

Sometimes old logs clog the buffer. Use the trash icon in Logcat to clear it before running your app again.

9. Update Android Studio and SDK Tools

Outdated tools can cause compatibility issues. Keep Android Studio, the Android SDK, and build tools updated.

Full Example: Debugging Logcat Visibility

Let’s simulate a common case where logs don’t appear due to filter issues and how to fix it:

import android.os.Bundle
import android.util.Log
import androidx.appcompat.app.AppCompatActivity

class DebugExampleActivity : AppCompatActivity() {

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

        testLogging()
    }

    private fun testLogging() {
        // Always use a unique TAG
        val TAG = "DebugExample"

        Log.d(TAG, "This is a debug message")
        Log.i(TAG, "This is an info message")
        Log.w(TAG, "This is a warning")
        Log.e(TAG, "This is an error message")
    }
}

Fix Applied: In Logcat, select the device running DebugExampleActivity, set the filter to Verbose, and choose Show only selected application.

Conclusion

The issue of Kotlin Logcat not showing logs is usually related to filters, build configurations, or device connections. By following the quick fixes above, you can ensure Logcat reliably displays your application logs, making debugging faster and more effective. Always verify your filter settings first before diving into deeper configurations — in many cases, the fix is simpler than you think.