(#) Missing Android XML namespace !!! ERROR: Missing Android XML namespace This is an error. Id : `MissingPrefix` Summary : Missing Android XML namespace Severity : Error Category : Correctness Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : 7.0.0 (July 2021) 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/MissingPrefixDetector.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/MissingPrefixDetectorTest.kt) Most Android views have attributes in the Android namespace. When referencing these attributes you **must** include the namespace prefix, or your attribute will be interpreted by `aapt` as just a custom attribute. Similarly, in manifest files, nearly all attributes should be in the `android:` namespace. !!! 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/namespace.xml:2:Error: Attribute is missing the Android namespace prefix [MissingPrefix] <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:other="http://foo.bar" android:id="@+id/newlinear" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" orientation="true"> ------------------ res/layout/namespace.xml:3:Error: Attribute is missing the Android namespace prefix [MissingPrefix] <Button style="@style/setupWizardOuterFrame" android.text="Button" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content"/> --------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `res/layout/namespace.xml`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:other="http://foo.bar" android:id="@+id/newlinear" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" orientation="true"> <Button style="@style/setupWizardOuterFrame" android.text="Button" android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <ImageView android:style="@style/bogus" android:id="@+id/android_logo" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/android_button" android:focusable="false" android:clickable="false" android:layout_weight="1.0" /> <LinearLayout other:orientation="horizontal"/> </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/MissingPrefixDetectorTest.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, `MissingPrefixDetector.testBasic`. 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="MissingPrefix"` 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="MissingPrefix" 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 'MissingPrefix' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore MissingPrefix ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).