Question

我的目标：通过首选项设置夜间模式并实时更新用户界面。

到目前为止：完成。但是，当我单击返回到标题的首选项屏幕时，无法再次回到不同的首选项屏幕。

详细介绍：那时我的设置非常简单。我正在按照Android Studio（3.1.4）的SettingsActivity设置的预设进行操作，该预设具有AppCompatPreferenceActivity模板。我有一个主屏幕和两个更深的屏幕。

我的第一个屏幕有两个选择：常规和关于。选择“常规”后，我将加载具有一个Switch首选项（即“夜间模式”）的GeneralPreferenceFragment。如果将其设置为打开，它将实时切换主题，而当我返回时，也将在我的第一个设置屏幕上完成。

问题：当我确实更改了主题时，请返回主设置屏幕，并尝试重新访问“常规”或“关于”屏幕时，我无法再进行更深入的介绍了！如果我将首选项设置为偶数，以使最终主题变为初始主题，我可以像访问任何内容一样访问它们。

SettingsActivity类

class SettingsActivity : AppCompatPreferenceActivity() {

// To be used for live changes in night mode
private var mCurrentNightMode: Int = 0
private val TAG = "SettingsActivity"
private var mThemeId = 0

/**
 * Doing this hack to add my own actionbar on top since it wasn't there on its own
 */
override fun onPostCreate(savedInstanceState: Bundle?) {
    super.onPostCreate(savedInstanceState)
    Log.d(TAG, "onPostCreate")

    val root = findViewById<View>(android.R.id.list).parent.parent.parent as LinearLayout
    val bar = LayoutInflater.from(this).inflate(R.layout.settings_toolbar, root, false) as Toolbar
    root.addView(bar, 0) // insert at top
    bar.setNavigationOnClickListener {finish()}
}

override fun setTheme(resid: Int) {
    super.setTheme(resid)
    mThemeId = resid
}

override fun onCreate(savedInstanceState: Bundle?) {
    if (delegate.applyDayNight() && (mThemeId != 0) ) {
        // If DayNight has been applied, we need to re-apply the theme for
        // the changes to take effect. On API 23+, we should bypass
        // setTheme(), which will no-op if the theme ID is identical to the
        // current theme ID.
        if (Build.VERSION.SDK_INT >= 23) {
            onApplyThemeResource(theme, mThemeId, false);
        } else {
            setTheme(mThemeId);
        }
    }
    super.onCreate(savedInstanceState)
    Log.d("SettingsActivity", "onCreate")
    setupActionBar()

    // Storing the current value so if we come back we'll check on postResume for any changes
    mCurrentNightMode = getCurrentNightMode();
}

// Comparing current and last known night mode value
private fun hasNightModeChanged(): Boolean {
    return mCurrentNightMode != getCurrentNightMode()
}

private fun getCurrentNightMode(): Int {
    return resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK
}

override fun onPostResume() {
    super.onPostResume()

    // Self-explanatory. When I load back into this screen, if there's a change in the theme, load it back!
    if(hasNightModeChanged()) {
        recreate()
    }
}

/**
 * Set up the [android.app.ActionBar], if the API is available.
 */
private fun setupActionBar() {
    supportActionBar?.setDisplayHomeAsUpEnabled(true)
}

/**
 * {@inheritDoc}
 */
override fun onIsMultiPane(): Boolean {
    return isXLargeTablet(this)
}

/**
 * {@inheritDoc}
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
override fun onBuildHeaders(target: List<PreferenceActivity.Header>) {
    loadHeadersFromResource(R.xml.pref_headers, target)
}

/**
 * This method stops fragment injection in malicious applications.
 * Make sure to deny any unknown fragments here.
 */
override fun isValidFragment(fragmentName: String): Boolean {
    return PreferenceFragment::class.java.name == fragmentName
            || GeneralPreferenceFragment::class.java.name == fragmentName
            || DataSyncPreferenceFragment::class.java.name == fragmentName
            || NotificationPreferenceFragment::class.java.name == fragmentName
            || AboutFragment::class.java.name == fragmentName
}

/**
 * This fragment shows general preferences only. It is used when the
 * activity is showing a two-pane settings UI.
 */
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
class GeneralPreferenceFragment : PreferenceFragment() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        addPreferencesFromResource(R.xml.pref_general)
        setHasOptionsMenu(true)

        // Bind the summaries of EditText/List/Dialog/Ringtone preferences
        // to their values. When their values change, their summaries are
        // updated to reflect the new value, per the Android Design
        // guidelines.
        findPreference("night_mode").setOnPreferenceChangeListener { preference, newValue ->
            val booleanValue = newValue as Boolean

            if(booleanValue) {
                AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES)
            } else {
                AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
            }

            activity.recreate()
            true
        }
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        val id = item.itemId
        if (id == android.R.id.home) {
            startActivity(Intent(activity, SettingsActivity::class.java))
            return true
        }
        return super.onOptionsItemSelected(item)
    }
}
 .
 .
 .
 companion object {
 // (didn't change anything here)
 }

我认为在“重新创建”调用中会出现问题。就像首选项列表的onItemClickListener为null或类似内容。

有人可以帮忙吗？

编辑：简化，现在我所有的逻辑都在SettingsActivity类中，我不需要在抽象类中

Answer 1

我不敢相信我通过添加delayRecreate而不是recreate（正在尝试与另一个问题this one做不同的事情）来解决它：

override fun onPostResume() {
    super.onPostResume()

    // Self-explanatory. When I load back into this screen, if there's a change in the theme, load it back!
    if(hasNightModeChanged()) {
        delayedRecreate()
    }
}

private fun delayedRecreate() {
    val handler = Handler()
    handler.postDelayed(this::recreate, 1)
}

但是，我不太喜欢屏幕重新创建有点延迟时的闪烁。如果有人有其他线索，将不胜感激！

Android通过AppCompatPreferenceActivity模板设置“夜间模式”可取消点击首选项标题

1 个答案: