小编Jim*_*nts的帖子

我有一个默认的 .mp4 文件，我想使用 ExoPlayer（在 Android 上）查看该文件。我用这个小视频：

http://techslides.com/demos/sample-videos/small.mp4

在应用程序中，我得到一个 base64 字符串，即视频。当我将上面的视频粘贴到该网站时：

https://base64.guru/converter/encode/video

它显示的 Base64 值与应用程序中接收到的值相同，但会引发以下错误。

player.playFromBytes(currentVideoBase64?.toByteArray()!!)

override fun playFromBytes(byteArray: ByteArray) {
    val mediaSource = createMediaSourceFromByteArray(byteArray)
    exoPlayer.prepare(mediaSource)
    exoPlayer.playWhenReady = true
}

private fun createMediaSourceFromByteArray(data: ByteArray): MediaSource {
    val byteArrayDataSource = ByteArrayDataSource(data)
    val factory = DataSource.Factory { byteArrayDataSource }
    val mediaSource = ProgressiveMediaSource.Factory(factory, DefaultExtractorsFactory())
            .createMediaSource(Uri.EMPTY)

    return Objects.requireNonNull(mediaSource, "MediaSource cannot be null")
}

错误信息：

2019-09-18 18:09:59.970 18009-18743/ E/ExoPlayerImplInternal: Source error.
    com.google.android.exoplayer2.source.UnrecognizedInputFormatException: None of the available extractors (MatroskaExtractor, FragmentedMp4Extractor, Mp4Extractor, Mp3Extractor, AdtsExtractor, Ac3Extractor, TsExtractor, FlvExtractor, …

我在我的应用程序中实现了黑暗/夜间模式切换，我从Google I/O App复制了该实现。

我创建了一个可以包含在 ViewModel 中的ThemedActivityDelegate 。实际更改为亮或暗是使用扩展函数完成的：updateForTheme。

但我看到SettingsActivity白色短暂闪烁，然后变成黑色。虽然我updateForTheme之前把方法放了setContentView。

主要活动：

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
    viewModel = ViewModelProvider(this, viewModelFactory).get(MainViewModel::class.java)
    updateForTheme(viewModel.currentTheme)

    lifecycleScope.launch {
        lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED) {
            launch {
                viewModel.theme.collect { theme ->
                    updateForTheme(theme)
                }
            }
        }
    }
}

扩展.kt：

fun AppCompatActivity.updateForTheme(theme: Theme) = when (theme) {
    Theme.DARK -> delegate.localNightMode = AppCompatDelegate.MODE_NIGHT_YES
    Theme.LIGHT -> delegate.localNightMode = AppCompatDelegate.MODE_NIGHT_NO
    Theme.SYSTEM -> delegate.localNightMode = AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM
    Theme.BATTERY_SAVER -> delegate.localNightMode = AppCompatDelegate.MODE_NIGHT_AUTO_BATTERY …

• 我有Android Studio 3.1.2.
• 我有Kotlin 1.2.41-release-Studio3.1-1.

没有对annotationProcessor的引用build.gradle,我只使用kotlin-kapt:

apply plugin: 'kotlin-kapt'

我的事件日志显示0警告/错误:

10-05-18
13:24   Executing tasks: [clean, :storage:generateDebugSources, :pagination:generateDebugSources, :validation:generateDebugSources, :validation-ui:generateDebugSources, :misnap:generateDebugSources, :openam:generateDebugSources, :domain:generateDebugSources, :core:generateDebugSources, :crypto:generateDebugSources, :interactors:generateDebugSources, :analytics:generateDebugSources, :app:generateDevNlDebugSources, :midlayer:generateDebugSources, :coverflow:generateDebugSources, :debug-ui:generateDebugSources, :encap:generateDebugSources]

13:24   Gradle build finished in 7s 550ms

13:25   Executing tasks: [:app:assembleDevNlDebug]

13:26   Gradle build finished in 1m 2s 902ms

这是输出:

org.gradle.api.GradleException: Compilation error. See log for more details
    at org.jetbrains.kotlin.gradle.tasks.TasksUtilsKt.throwGradleExceptionIfError(tasksUtils.kt:8)
    at org.jetbrains.kotlin.gradle.internal.KaptTask.compile(KaptTask.kt:124)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
    at org.gradle.api.internal.project.taskfactory.StandardTaskAction.doExecute(StandardTaskAction.java:46)
    at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:39) …

安装Android Studio 3.3后,"选择部署目标"在没有连接的设备和不存在的模拟器之间切换.

每次尝试在模拟器或真实设备上安装应用程序时,都会显示以下错误消息:

02/01 18:05:26: Launching app
$ adb push /Users/jimclermonts/Documents/Android-Code/sources/app/build/outputs/apk/acceptance/debug/app-acceptance-debug.apk /data/local/tmp/nl.mycompanyname.acc
Device emulator-5556disconnected, monitoring stopped.
Error while Installing APK

这是一个显示奇怪切换的视频:

我尝试以编程方式杀死它但它不断启动自己:

Mac-van-Jim:~ jimclermonts$ adb devices
List of devices attached
emulator-5556   offline

Mac-van-Jim:~ jimclermonts$ adb devices
List of devices attached

Mac-van-Jim:~ jimclermonts$ adb devices
List of devices attached

Mac-van-Jim:~ jimclermonts$ adb devices
List of devices attached
emulator-5556   offline

Mac-van-Jim:~ jimclermonts$ adb devices
List of devices attached

Mac-van-Jim:~ jimclermonts$ adb -s emulator-5556 emu kill
Mac-van-Jim:~ jimclermonts$ adb -s emulator-5556 emu …

当我在扩展FirebaseMessagingService的服务中收到Push消息并在此类中启动Activity时,将执行以下生命周期事件/方法:

• Push Message启动VideoRingingActivity
• 启动VideoRingingActivity
• 的onCreate
• disableLockScreen
• 屏幕从黑色切换到锁定屏幕,因此它不显示VideoRingingActivity
• 在onStart
• 的onResume
• 在onPause
• 的onStop
• 现在显示了实际的VideoRingingActivity？我期待在setContentView(R.layout.activity_video_ringing)之后出现这个问题
• onRestart
• 在onStart
• 的onResume

我开发了下面的解决方案,我在其中添加一个布尔值,以确定屏幕是否打开/关闭.但这很麻烦,当屏幕在锁定模式下打开时,它不起作用.

因为当屏幕未关闭且显示MainActivity,并且接收到推送消息时,该行为是默认的生命周期行为,因此是正确的.打开屏幕并显示MainActivity时,这是相同的流程:

• 的onCreate
• 在onStart
• 的onResume

这是正确的,也是可以预期的.

class VideoRingingActivity : BaseActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        if (ViewUtils.isScreenActive(activity)) {
            screenIsNotLocked = true
        }
        ViewUtils.disableLockScreen(this)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_video_ringing)
    }

    override fun onStart() {
        super.onStart()
        if (screenIsNotLocked) {
        }
    }

    override fun onResume() {
        super.onResume()
        if (screenIsNotLocked) {
        }
    }

    override fun onPause() {
        super.onPause()
        if (screenIsNotLocked) {
        }
    }

    override fun onStop() {
        super.onStop()
        if …

我编写了一种方法来禁用Android锁定屏幕，并使屏幕从待机状态（用于拨号）打开。此方法可正常工作30秒，但随后会触发待机屏幕，该屏幕短暂闪烁。这会触发onPause，onStop，onResume。这不应该发生。哪个标志不正确？实施必须从最新的Android版本开始，直到API 19。

此错误仅在<8.0以下的Android设备上发生。

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    disableLockScreen(this)
    setContentView(R.layout.activity_main)
    Log.i("AppLifecycleTest", "onCreate")
}

override fun onResume() {
    super.onResume()
    Log.i("AppLifecycleTest", "onResume")
}

override fun onPause() {
    super.onPause()
    Log.i("AppLifecycleTest", "onPause")
}

override fun onStop() {
    super.onStop()
    Log.i("AppLifecycleTest", "onStop")
}

override fun onDestroy() {
    super.onDestroy()
    Log.i("AppLifecycleTest", "onDestroy")
}

@Suppress("DEPRECATION")
private fun disableLockScreen(activity: Activity) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) {
        activity.setShowWhenLocked(true)
        activity.setTurnScreenOn(true)
    }
    val lock =
        (activity.getSystemService(Activity.KEYGUARD_SERVICE) as KeyguardManager).newKeyguardLock(Context.KEYGUARD_SERVICE)
    val powerManager = activity.getSystemService(Context.POWER_SERVICE) as PowerManager
    val wake = powerManager.newWakeLock(
        PowerManager.FULL_WAKE_LOCK or
                PowerManager.ACQUIRE_CAUSES_WAKEUP or …

我正在初始化一个带有图标（国家/地区标志）和电话号码的下拉菜单。前缀（字符串）。当我在 XML 中设置 drawable 时，它​​可以工作：

app:drawableStartCompat="@drawable/flag_afn"

但是当我以编程方式找到视图时，使用

setCompoundDrawablesWithIntrinsicBounds 

它不起作用。

主活动.kt

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val viewGroup =
            (findViewById<View>(android.R.id.content) as ViewGroup).getChildAt(0) as ViewGroup

        initializeSpinner(viewGroup)
    }

    private fun initializeSpinner(parent: ViewGroup) {
        ArrayAdapter.createFromResource(
            this,
            R.array.phone_country_codes,
            R.layout.spinner_dropdown_item
        ).also { adapter ->
            // Specify the layout to use when the list of choices appears
            adapter.setDropDownViewResource(R.layout.spinner_dropdown_item)
            // Apply the adapter to the spinner
            phonePrefix.adapter = adapter

            for (cnt in 0 until adapter.count) {
                val drawable = ContextCompat.getDrawable(this, R.drawable.flag_bmd)

                val view = adapter.getView(cnt, null, …

from abc import abstractmethod, ABCMeta

class AbstractBase(object):
  __metaclass__ = ABCMeta

  @abstractmethod
  def must_implement_this_method(self):
      raise NotImplementedError()

class ConcreteClass(AbstractBase):

   def extra_function(self):
       print('hello')

   # def must_implement_this_method(self):
     # print("Concrete implementation")


d = ConcreteClass()  # no error
d.extra_function()

我在使用Python 3.4.我想定义一个抽象基类,它定义了需要由它的子类实现的某些函数.但是当子类没有实现函数时,Python不会引发NotImplementedError ...

它必须是这样的:

目前它看起来像这样:

圆角矩形并不重要.但是未经检查的状态必须是黑色的.这是我的代码:

<CheckBox
    android:id="@+id/checkbox"
    android:buttonTint="@color/orange"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

这是我正在使用的主题:

  "Theme.AppCompat.Light.NoActionBar"

我也试过这个:

<style name="checkbox_style" parent="Bijenkorf">
    <item name="material_grey_600">@color/black</item>
</style>

因为未选中的默认值为#757575.我在主题中看了这个,它是"material_grey_600".但这不编译.有任何想法吗？

我正在尝试在 Android 上运行 HtmlUnit。我认为这个答案曾经适用于较旧的库，但不再适用。与此问题相关的其他线程与 Android 上的 Kotlin 无关或已过时。

考虑下面的代码：

https://github.com/JimClermonts/HtmlUnit-for-Android

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    doAsync {
        val webClient = WebClient()
        var page: HtmlPage = webClient.getPage<HtmlPage>("http://www.google.com")
        val searchBox = page.getElementByName<HtmlInput>("q")
        searchBox.valueAttribute = "htmlunit"

        val googleSearchSubmitButton: HtmlSubmitInput = page.getElementByName("btnG") // sometimes it's "btnK"
        page = googleSearchSubmitButton.click()

        val resultStatsDiv: HtmlDivision = page.getFirstByXPath("//div[@id='resultStats']")

        System.out.println(resultStatsDiv.asText()) // About 309,000 results

        webClient.close()
    }
}

这是我的项目依赖项：

dependencies {
    implementation group: 'commons-io', name: 'commons-io', version: '2.6'
//    implementation group: 'commons-logging', name: 'commons-logging', version: '1.2' …