The logging tag can be at most 23 characters

Question

Since update AS 1.1 Preview 2, I'm getting red lines under all my Log messages

Log.d(TAG, "message");

With message: "The logging tag can be at most 23 characters..".

I didn't update anything fundamentally, except Android Studio itself. Is this a bug?

Answer 1

You can disable it if you so choose.

In Android Studio, Analyze->Inspect Code.

Under Inspection Profile, click on the button with the 3 horizontal dots.

The following window should open. Search for "log" and uncheck "Too Long Log Tags".

Update: Android Studio 2.2, it is located under Android Lint: Correctness

Answer 2

No, it's not a bug.

From Android Studio's Recent Changes on 1.1 Preview 2,

Checks that the tag passed to the logging calls, if its value can be resolved, is at most 23 characters long (as required by the Logging API.)

As shortly explained on the recent changes, it's due to how Log API doesn't allow tag that exceeds 23 characters.

SLF4J Android has an explanation to this:

[...] the length of such tags is currently limited to 23 characters (23 = 32 - 8 for namespace prefix - 1 for C terminator)

which matches the Android's source code.

Currently, the only function that explicitly mentions this exception is Log.isLoggable(),

...

Throws

IllegalArgumentException is thrown if the tag.length() > 23.

However, based on the comments, apparently the logger does throw the exception on release mode (it's ignored in debug mode).

You can disable the lint checking by following Terence's answer, but you've been warned.

Answer 3

Complementing the answer by @Terence

You can also turn off the specific check via gradle with this in your build.gradle file:

lintOptions {
    disable 'LongLogTag'
}

Or by adding a lint.xml file to your project with xml:

<?xml version="1.0" encoding="UTF-8"?>
<lint>
    <issue id="LongLogTag" severity="ignore" />
</lint>

Answer 4

You can never ignore this lint check, it definitely could bring unexpected results on your release version since it throws exceptions and stops executing (it would not crash your app).

I have had a terrible lesson learned recently: it's OK on debug mode, but behave differently on release version.

Answer 5

This is recent change and In this build, its a new lint check. Which says,

Checks that the tag passed to the logging calls, if its value can be resolved, is at most 23 characters long (as required by the Logging API.)

For more info, read 3rd point in below link.

https://sites.google.com/a/android.com/tools/recent/androidstudio11preview2

If you dont want to get this, minimize the number of characters in your TAG and make sure that they wont cross the length more than 23.

Answer 6

To explain why this happens:

According to AOSP source code you can log with any tag you want. The problem is in Log.isLoggable.

Log.isLoggable checks the system property log.tag.<YOUR_TAG> if the priority you want to log is enabled. Here's documentation of this mechanism:

public static boolean isLoggable (String tag, int level)

Checks to see whether or not a log for the specified tag is loggable at the specified level. The default level of any tag is set to INFO. This means that any level above and including INFO will be logged. Before you make any calls to a logging method you should check to see if your tag should be logged. You can change the default level by setting a system property: 'setprop log.tag. ' Where level is either VERBOSE, DEBUG, INFO, WARN, ERROR, ASSERT, or SUPPRESS. SUPPRESS will turn off all logging for your tag. You can also create a local.prop file that with the following in it: 'log.tag.=' and place that in /data/local.prop.

Source: https://developer.android.com/reference/android/util/Log#isLoggable(java.lang.String,%20int)

Below API 26 (Oreo) the limit of system property keys was 31 characters. And "log.tag.".length() + 23 equals 31. If you call Log.isLoggable below Android Oreo with a tag longer than 23 characters it will throw, as described in the source code. Since Android O this limit no longer applies.

The Lint rule exists just to shield you from all these (typically) unnecessary details.

---

The documentation for Log.isLoggable also states the IllegalArgumentException will not be thrown since API 24, which according to my findings, is wrong. Follow: https://issuetracker.google.com/issues/124593220

Answer 7

Solution. Year 2020 ver.

build.gradle (app)

android {
    lintOptions {
        disable 'LongLogTag'
    } // put this. 
}

Answer 8

This error was thrown for me for a node_module library, complaining about a separate node_mode library.

I added this lint options property within that node_module library's build gradle file.

  android {
      lintOptions {
          abortOnError false
      }
  }

The library was aws-amplify push notification.

Error: Execution failed for task ':@aws-amplify/pushnotification:lint'

File updated: node_modules/@aws-amplify/pushnotification/android/build.gradle