To log a message from a Kotlin Android app, import android.util.Log and call a method such as Log.d(TAG, "Loading data"). Run the app, then open Android Studio’s Logcat window at View > Tool Windows > Logcat to find the entry. You can also inspect device logs from a terminal with adb logcat.
Write a message to Logcat from Kotlin
Android’s logging API is android.util.Log. A call supplies a tag, which identifies the source, and a message. This minimal example follows Android’s documented Kotlin pattern:
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import android.util.Log
private const val TAG = "MainActivity"
fun loadData() {
Log.d(TAG, "Loading data")
}Choose a priority that fits the diagnostic. Android provides verbose, debug, info, warning, and error logging methods; for example, Log.d writes a debug-level entry. Logcat displays the entry’s priority alongside its other metadata.
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- Please note, this device does not support E-SIM; This 4G model is compatible with all GSM networks worldwide outside of the U.S. In the US, ONLY compatible with T-Mobile and their MVNO's (Metro and Standup). It will NOT work with other CDMA carriers, and it is also not compatible with their MVNO (Visible, Xfinity Mobile, US Mobile, Cricket Wireless, etc).
- Compatibility with certain third-party devices and accessibility accessories, including some hearing aids, may vary depending on manufacturer support, Bluetooth protocols, software compatibility, and regional firmware limitations. For additional hearing aid compatibility information, please refer to Samsung’s official support documentation.
- Camera: 50 MP, f/1.8, (wide), 1/2.76", 0.64µm, AF | 50 MP, f/1.8, (wide), 1/2.76", 0.64µm, AF | 2 MP, f/2.4, (macro). Battery: 5000 mAh, non-removable | A power adapter is NOT included.
try {
// Work that may fail
} catch (e: SomeException) {
Log.d(TAG, "someOtherMethod()", e)
}This writes exception information with the message, making the stack trace available in Logcat. Avoid putting passwords, tokens, or other sensitive user data in log messages.
Find app messages in Android Studio
- Build and run the app on an emulator or a physical Android device.
- In Android Studio, choose View > Tool Windows > Logcat.
- Use the device and app controls and the query field to narrow the entries you want to inspect.
Logcat includes output from the selected app as well as Android services and system components. An entry can show its timestamp, process and thread IDs, tag, package, priority, and message. Use the tag or package to recognize your app’s output, or filter by priority when you are looking for warnings and errors. The window also presents exception stack traces and includes controls to pause, clear, restart, or resume scrolling.
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Filter by tag, package, level, or age
Android Studio’s query field accepts key-value filters. Each of these is a separate example:
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tag:MainActivity
level:INFO
age:5mYou can combine expressions. This example matches entries tagged MainActivity or at error level, then restricts the result to your app’s package:
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(tag:MainActivity | level:ERROR) & package:mineDocumented query keys include tag, package, process, message, level, and age. A level filter includes the chosen level and more severe levels, so level:INFO also matches warnings and errors. Age values use integer durations such as 5m; the comparison relies on the host timestamp, so clock differences between the computer and device can affect age filtering.
Use adb logcat in a terminal
For a command-line view, connect a device or start an emulator and run:
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- YOUR CONTENT, SUPER SMOOTH: The ultra-clear 6.7" FHD+ Super AMOLED display of Galaxy A17 5G helps bring your content to life, whether you're scrolling through recipes or video chatting with loved ones.¹
- LIVE FAST. CHARGE FASTER: Focus more on the moment and less on your battery percentage with Galaxy A17 5G. Super Fast Charging powers up your battery so you can get back to life sooner.²
- MEMORIES MADE PICTURE PERFECT: Capture every angle in stunning clarity, from wide family photos to close-ups of friends, with the triple-lens camera on Galaxy A17 5G.
- NEED MORE STORAGE? WE HAVE YOU COVERED: With an improved 2TB of expandable storage, Galaxy A17 5G makes it easy to keep cherished photos, videos and important files readily accessible whenever you need them.³
- BUILT TO LAST: With an improved IP54 rating, Galaxy A17 5G is even more durable than before.⁴ It’s built to resist splashes and dust and comes with a stronger yet slimmer Gorilla Glass Victus front and Glass Fiber Reinforced Polymer back.
adb logcat MyApp:D '*:S'The MyApp:D rule requests debug priority and more severe entries for the tag MyApp. The *:S rule suppresses other tags. Keep the wildcard rule quoted in shells that might otherwise expand *.
The command-line filter syntax is different from Android Studio’s key-value queries. The CLI also offers output formats with -v, including threadtime (the documented default), brief, and time. Available options can vary with the target device’s Android version; check adb logcat --help on that device if a format or option is unavailable.
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- US Model – Global Connectivity – Compatible with Most GSM Carriers like T-Mobile, AT&T, MetroPCS, etc. Will Also work with CDMA Carriers Such as Verizon, Straight Talk.
Choose the viewing route that fits your workflow
| Consideration | Android Studio Logcat | adb logcat |
|---|---|---|
| Interface | IDE window with device selection and a query field | Terminal command |
| Filtering | Key-value queries such as package:mine, tag:MainActivity, and level:ERROR |
Tag and minimum-priority rules such as MyApp:D and *:S |
| Output controls | IDE view controls and query history | -v formats such as threadtime and brief |
| A useful fit | Finding and inspecting app output visually while working in the IDE | Narrowing output or using a terminal-based workflow |
Both routes inspect Android logs; neither is the only way to debug an app.
Keep debug logging out of release builds
Android’s debugging guidance recommends removing debug log messages and stack-trace print calls before publishing, or putting them behind a DEBUG flag. Review the release build deliberately rather than assuming logging is automatically stripped. This is a release-hygiene measure, not a guarantee that every kind of logged data is private.
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