(#) Incorrect constant !!! ERROR: Incorrect constant This is an error. Id : `WrongConstant` Summary : Incorrect constant Severity : Error Category : Correctness Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : 3.1.0 (March 2018) Affects : Kotlin and Java files Editing : This check runs on the fly in the IDE editor Implementation : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/TypedefDetector.kt) Tests : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/TypedefDetectorTest.kt) Ensures that when parameter in a method only allows a specific set of constants, calls obey those rules. !!! Tip This lint check has an associated quickfix available in the IDE. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/DetailInfoTab.kt:9:Error: Must be one of: View.LAYOUT_DIRECTION_LTR, View.LAYOUT_DIRECTION_RTL, View.LAYOUT_DIRECTION_INHERIT, View.LAYOUT_DIRECTION_LOCALE [WrongConstant] view.layoutDirection = View.TEXT_ALIGNMENT_TEXT_START // ERROR - not one of the allowed values ------------------------------ src/DetailInfoTab.kt:28:Error: Must be one of: DetailInfoTabKt.CONST_1, DetailInfoTabKt.CONST_2, DetailInfoTabKt.CONST_3 [WrongConstant] test(UNRELATED) // ERROR - not part of the @DetailsInfoTab list --------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `src/DetailInfoTab.kt`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers import android.view.View import androidx.annotation.IntDef // Example of using Android API already annotated with @IntDef: fun setAlignment(view: View) { view.layoutDirection = View.LAYOUT_DIRECTION_RTL // OK view.layoutDirection = View.TEXT_ALIGNMENT_TEXT_START // ERROR - not one of the allowed values } // Custom example creating your own typedef: const val CONST_1 = -1 const val CONST_2 = 2 const val CONST_3 = 0 const val UNRELATED = 1 @IntDef(CONST_1, CONST_2, CONST_3) @Retention(AnnotationRetention.SOURCE) annotation class DetailInfoTab fun test(@DetailInfoTab tab: Int) { } fun test() { test(CONST_1) // OK test(UNRELATED) // ERROR - not part of the @DetailsInfoTab list } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the source code ([TypedefDetectorTest.kt](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/TypedefDetectorTest.kt) [RangeDetectorTest.kt](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/RangeDetectorTest.kt) [LintIssueDocGeneratorTest.kt](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/LintIssueDocGeneratorTest.kt) for the unit tests for this check to see additional scenarios. (##) Suppressing You can suppress false positives using one of the following mechanisms: * Using a suppression annotation like this on the enclosing element: ```kt // Kotlin @Suppress("WrongConstant") fun method() { problematicStatement() } ``` or ```java // Java @SuppressWarnings("WrongConstant") void method() { problematicStatement(); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection WrongConstant problematicStatement() ``` * Using a special `lint.xml` file in the source tree which turns off the check in that folder and any sub folder. A simple file might look like this: ```xml <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="WrongConstant" severity="ignore" /> </lint> ``` Instead of `ignore` you can also change the severity here, for example from `error` to `warning`. You can find additional documentation on how to filter issues by path, regular expression and so on [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html). * In Gradle projects, using the DSL syntax to configure lint. For example, you can use something like ```gradle lintOptions { disable 'WrongConstant' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore WrongConstant ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).