(#) Instead of calling the Schedulers factory methods directly inject the Schedulers !!! WARNING: Instead of calling the Schedulers factory methods directly inject the Schedulers This is a warning. Id : `RxJava2SchedulersFactoryCall` Summary : Instead of calling the Schedulers factory methods directly inject the Schedulers Severity : Warning Category : Correctness Platform : Any Vendor : vanniktech/lint-rules/ Feedback : https://github.com/vanniktech/lint-rules/issues Min : Lint 8.0 and 8.1 Compiled : Lint 8.0 and 8.1 Artifact : [com.vanniktech:lint-rules-rxjava2](com_vanniktech_lint-rules-rxjava2.md.html) Since : 0.6.0 Affects : Kotlin and Java files Editing : This check runs on the fly in the IDE editor Implementation : [Source Code](https://github.com/vanniktech/lint-rules/tree/master/lint-rules-rxjava2-lint/src/main/kotlin/com/vanniktech/lintrules/rxjava2/RxJava2SchedulersFactoryCallDetector.kt) Tests : [Source Code](https://github.com/vanniktech/lint-rules/tree/master/lint-rules-rxjava2-lint/src/test/kotlin/com/vanniktech/lintrules/rxjava2/RxJava2SchedulersFactoryCallDetectorTest.kt) Injecting the Schedulers instead of accessing them via the factory methods has the benefit that unit testing is way easier. Instead of overriding them via the Plugin mechanism we can just pass a custom Scheduler. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/foo/Example.java:9:Warning: Inject this Scheduler instead of calling it directly [RxJava2SchedulersFactoryCall] return Schedulers.io(); -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `src/foo/Example.java`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers package foo; import io.reactivex.annotations.CheckReturnValue; import io.reactivex.Scheduler; import io.reactivex.schedulers.Schedulers; class Example { @CheckReturnValue Scheduler provideSchedulerIo() { return Schedulers.io(); } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://github.com/vanniktech/lint-rules/tree/master/lint-rules-rxjava2-lint/src/test/kotlin/com/vanniktech/lintrules/rxjava2/RxJava2SchedulersFactoryCallDetectorTest.kt) for the unit tests for this check to see additional scenarios. The above example was automatically extracted from the first unit test found for this lint check, `RxJava2SchedulersFactoryCallDetector.ioCallInsideCheckReturnValueMethod`. To report a problem with this extracted sample, visit https://github.com/vanniktech/lint-rules/issues. (##) Including !!! This is not a built-in check. To include it, add the below dependency to your project. This lint check is included in the lint documentation, but the Android team may or may not agree with its recommendations. ``` // build.gradle.kts lintChecks("com.vanniktech:lint-rules-rxjava2:0.25.0") // build.gradle lintChecks 'com.vanniktech:lint-rules-rxjava2:0.25.0' // build.gradle.kts with version catalogs: lintChecks(libs.lint.rules.rxjava2) # libs.versions.toml [versions] lint-rules-rxjava2 = "0.25.0" [libraries] # For clarity and text wrapping purposes the following declaration is # shown split up across lines, but in TOML it needs to be on a single # line (see https://github.com/toml-lang/toml/issues/516) so adjust # when pasting into libs.versions.toml: lint-rules-rxjava2 = { module = "com.vanniktech:lint-rules-rxjava2", version.ref = "lint-rules-rxjava2" } ``` 0.25.0 is the version this documentation was generated from; there may be newer versions available. [Additional details about com.vanniktech:lint-rules-rxjava2](com_vanniktech_lint-rules-rxjava2.md.html). (##) 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("RxJava2SchedulersFactoryCall") fun method() { io(...) } ``` or ```java // Java @SuppressWarnings("RxJava2SchedulersFactoryCall") void method() { io(...); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection RxJava2SchedulersFactoryCall 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="RxJava2SchedulersFactoryCall" 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 'RxJava2SchedulersFactoryCall' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore RxJava2SchedulersFactoryCall ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).