(#) Touchscreen not optional
!!! ERROR: Touchscreen not optional
This is an error.
Id
: `ImpliedTouchscreenHardware`
Summary
: Touchscreen not optional
Severity
: Error
Category
: Correctness
Platform
: Android
Vendor
: Android Open Source Project
Feedback
: https://issuetracker.google.com/issues/new?component=192708
Since
: 2.3.0 (March 2017)
Affects
: Manifest files
Editing
: This check runs on the fly in the IDE editor
See
: https://developer.android.com/guide/topics/manifest/uses-feature-element.html
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/AndroidTvDetector.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/AndroidTvDetectorTest.java)
Apps require the `android.hardware.touchscreen` feature by default. If
you want your app to be available on TV, you must also explicitly
declare that a touchscreen is not required as follows:
``
(##) Example
Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
AndroidManifest.xml:2:Error: Hardware feature
android.hardware.touchscreen not explicitly marked as optional
[ImpliedTouchscreenHardware]
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
--------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Here is the source file referenced above:
`AndroidManifest.xml`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~xml linenumbers
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<uses-feature android:name="android.software.leanback"/>
<uses-feature android:name="android.hardware.telephony"/>
</manifest>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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/AndroidTvDetectorTest.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, `AndroidTvDetector.testMissingUsesFeatureTouchScreen`.
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="ImpliedTouchscreenHardware"` 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"?>
<manifest xmlns:tools="http://schemas.android.com/tools">
...
<application tools:ignore="ImpliedTouchscreenHardware" .../>
...
</manifest>
```
* 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="ImpliedTouchscreenHardware" 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 'ImpliedTouchscreenHardware'
}
```
In Android projects this should be nested inside an `android { }`
block.
* For manual invocations of `lint`, using the `--ignore` flag:
```
$ lint --ignore ImpliedTouchscreenHardware ...`
```
* Last, but not least, using baselines, as discussed
[here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).