(#) File endsWith on file extensions !!! WARNING: File endsWith on file extensions This is a warning. Id : `FileEndsWithExt` Summary : File endsWith on file extensions Severity : Warning Category : Correctness Platform : Any Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : 7.1.0 (January 2022) 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/FileEndsWithDetector.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/FileEndsWithDetectorTest.kt) The Kotlin extension method `File.endsWith(suffix)` checks whole path components, not just string suffixes. This means that `File("foo.txt").endsWith(".txt")` will return false. Instead you might have intended `file.path.endsWith` or `file.extension.equals`. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/test.kt:4:Warning: File.endsWith compares whole filenames, not just file extensions; did you mean file.path.endsWith(".xml") ? [FileEndsWithExt] fun File.isXml() = endsWith(".xml") ---------------- src/test.kt:7:Warning: File.extension does not include the leading dot; did you mean "json" ? [FileEndsWithExt] fun File.isJson() = extension == ".json" ------- src/test.kt:8:Warning: File.extension does not include the leading dot; did you mean "webp" ? [FileEndsWithExt] fun isWebp(path: File) = path.extension.startsWith(".webp") ------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `src/test.kt`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers import java.io.File // This does not work -- it will return false for "foo/bar.xml", but true for "foo/.xml" fun File.isXml() = endsWith(".xml") // This does not work -- the extension property does not include the leading dot fun File.isJson() = extension == ".json" fun isWebp(path: File) = path.extension.startsWith(".webp") fun File.isText() = path.endsWith(".txt") // OK fun File.isPng() = extension == "png" // OK ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [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/FileEndsWithDetectorTest.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("FileEndsWithExt") fun method() { endsWith(...) } ``` or ```java // Java @SuppressWarnings("FileEndsWithExt") void method() { endsWith(...); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection FileEndsWithExt 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="FileEndsWithExt" 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 'FileEndsWithExt' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore FileEndsWithExt ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).