(#) Missing Initializer no-arg constructor !!! ERROR: Missing Initializer no-arg constructor This is an error, and is also enforced at build time when supported by the build system. For Android this means it will run during release builds. Id : `EnsureInitializerNoArgConstr` Summary : Missing Initializer no-arg constructor Severity : Fatal Category : Correctness Platform : Android Vendor : Android Open Source Project Identifier : androidx.startup Feedback : https://issuetracker.google.com/issues/new?component=823348 Min : Lint 8.0 and 8.1 Compiled : Lint 8.0 and 8.1 Artifact : [androidx.startup:startup-runtime](androidx_startup_startup-runtime.md.html) Since : 1.0.0 Affects : Kotlin and Java files Editing : This check runs on the fly in the IDE editor Implementation : [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/startup/startup-runtime-lint/src/main/java/androidx/startup/lint/InitializerConstructorDetector.kt) Tests : [Source Code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/startup/startup-runtime-lint/src/test/java/androidx/startup/lint/InitializerConstructorTest.kt) Copyright Year : 2020 Every `Initializer` must have a no argument constructor. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text com/example/TestInitializer.kt:5:Error: Missing Initializer no-arg constructor [EnsureInitializerNoArgConstr] class TestInitializer(val int: Int): Initializer<Unit> { ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `com/example/TestInitializer.kt`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers package com.example import androidx.startup.Initializer class TestInitializer(val int: Int): Initializer { } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:/startup/startup-runtime-lint/src/test/java/androidx/startup/lint/InitializerConstructorTest.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, `InitializerConstructorDetector.testFailureWhenZeroNoArgumentConstructorsArePresent`. To report a problem with this extracted sample, visit https://issuetracker.google.com/issues/new?component=823348. (##) Including !!! This is not a built-in check. To include it, add the below dependency to your project. ``` // build.gradle.kts implementation("androidx.startup:startup-runtime:1.2.0") // build.gradle implementation 'androidx.startup:startup-runtime:1.2.0' // build.gradle.kts with version catalogs: implementation(libs.startup.runtime) # libs.versions.toml [versions] startup-runtime = "1.2.0" [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: startup-runtime = { module = "androidx.startup:startup-runtime", version.ref = "startup-runtime" } ``` 1.2.0 is the version this documentation was generated from; there may be newer versions available. [Additional details about androidx.startup:startup-runtime](androidx_startup_startup-runtime.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("EnsureInitializerNoArgConstr") fun method() { problematicStatement() } ``` or ```java // Java @SuppressWarnings("EnsureInitializerNoArgConstr") void method() { problematicStatement(); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection EnsureInitializerNoArgConstr 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="EnsureInitializerNoArgConstr" 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 'EnsureInitializerNoArgConstr' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore EnsureInitializerNoArgConstr ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).