(#) Inefficient layout weight !!! WARNING: Inefficient layout weight This is a warning. Id : `InefficientWeight` Summary : Inefficient layout weight Severity : Warning Category : Performance Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : Initial Affects : 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/InefficientWeightDetector.java) 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/InefficientWeightDetectorTest.java) Copyright Year : 2011 When only a single widget in a `LinearLayout` defines a weight, it is more efficient to assign a width/height of `0dp` to it since it will absorb all the remaining space anyway. With a declared width/height of `0dp` it does not have to measure its own size first. !!! 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/inefficient_weight.xml:10:Warning: Use a layout_width of 0dp instead of match_parent for better performance [InefficientWeight] android:layout_width="match_parent" ----------------------------------- res/layout/inefficient_weight.xml:24:Warning: Use a layout_height of 0dp instead of wrap_content for better performance [InefficientWeight] android:layout_height="wrap_content" ------------------------------------ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `res/layout/inefficient_weight.xml`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1.0" /> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <Button android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1.0" /> </LinearLayout> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <Button android:layout_width="match_parent" android:layout_height="0dip" android:layout_weight="1.0" /> </LinearLayout> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" style="@style/MyStyle" android:layout_width="match_parent" android:layout_height="match_parent"> <Button android:layout_width="match_parent" android:layout_height="wrap_content" /> <Button android:layout_width="match_parent" android:layout_height="wrap_content" /> </LinearLayout> </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/InefficientWeightDetectorTest.java) 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, `InefficientWeightDetector.testWeights`. 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="InefficientWeight"` 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"`. ```xml <?xml version="1.0" encoding="UTF-8"?> <LinearLayout xmlns:tools="http://schemas.android.com/tools" tools:ignore="InefficientWeight" ...> ... </LinearLayout> ``` * 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="InefficientWeight" 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 'InefficientWeight' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore InefficientWeight ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).