(#) Redundant namespace !!! WARNING: Redundant namespace This is a warning. Id : `RedundantNamespace` Summary : Redundant namespace Severity : Warning Category : Performance Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : 3.4.0 (April 2019) Affects : Manifest files and resource 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/NamespaceDetector.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/NamespaceDetectorTest.kt) In Android XML documents, only specify the namespace on the root/document element. Namespace declarations elsewhere in the document are typically accidental leftovers from copy/pasting XML from other files or documentation. !!! 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 res/layout/customview2.xml:8:Warning: This namespace declaration is redundant [RedundantNamespace] xmlns:android="http://schemas.android.com/apk/res/android" ---------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `res/layout/customview2.xml`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/newlinear" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > <foo.bar.Baz xmlns:android="http://schemas.android.com/apk/res/android" xmlns:unrelated="http://un/related" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" /></LinearLayout> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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/NamespaceDetectorTest.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, `NamespaceDetector.testRedundantNamespace`. To report a problem with this extracted sample, visit https://issuetracker.google.com/issues/new?component=192708. (##) Suppressing You can suppress false positives using one of the following mechanisms: * Adding the suppression attribute `tools:ignore="RedundantNamespace"` on the problematic XML element (or one of its enclosing elements). You may also need to add the following namespace declaration on the root element in the XML file if it's not already there: `xmlns:tools="http://schemas.android.com/tools"`. * 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="RedundantNamespace" 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 'RedundantNamespace' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore RedundantNamespace ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).