后退按钮在首选项多个屏幕上不起作用

Question

我正在尝试使用多个屏幕来实现首选项。即使对于子首选项屏幕，操作栏后退按钮仅 returns 到 MainActivity。例如，我有一个根首选项屏幕，然后是一个子参考屏幕。 root 首选项屏幕上的后退按钮按预期返回主 activity。但是子参考屏幕上的后退按钮也返回到主 activity 而不是根首选项屏幕。下面是代码转储，因为我不确定我做错了什么。谢谢。

Androidmanifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.PreferencesTest">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".SettingsActivity2"
            android:label="@string/title_activity_settings2"
            android:parentActivityName=".SettingsActivity">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".SettingsActivity" />
        </activity>
        <activity
            android:name=".SettingsActivity"
            android:label="@string/title_activity_settings"
            android:parentActivityName=".MainActivity">
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value=".MainActivity" />
        </activity>
        <activity
            android:name=".MainActivity"
            android:theme="@style/AppTheme.Launcher">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

MainActivity.kt

class MainActivity : AppCompatActivity()
{
    override fun onCreate(savedInstanceState: Bundle?)
    {
        setTheme(R.style.AppTheme)
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    //Inflates settings menu button
    override fun onCreateOptionsMenu(menu: Menu): Boolean
    {
        val inflater: MenuInflater = menuInflater
        inflater.inflate(R.menu.settings_menu, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean
    {
        return when(item.itemId)
        {
            R.id.action_settings ->
            {
                val intent = Intent(this, SettingsActivity::class.java)
                startActivity(intent)
                true
            }
            else -> super.onOptionsItemSelected(item)
        }
    }
}

SettingsActivity.kt

class SettingsActivity : AppCompatActivity()
{

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

        supportFragmentManager
            .beginTransaction()
            .replace(R.id.settings, SettingsFragment())
            .commit()

        supportActionBar?.setDisplayHomeAsUpEnabled(true)

    }

    class SettingsFragment : PreferenceFragmentCompat()
    {
        override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?)
        {
            setPreferencesFromResource(R.xml.root_preferences, rootKey)
        }
    }
}

SettingsActivity2.kt

class SettingsActivity2 : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.settings_activity)
        supportFragmentManager
            .beginTransaction()
            .replace(R.id.settings, SettingsFragment())
            .commit()
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
    }

    class SettingsFragment : PreferenceFragmentCompat() {
        override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
            setPreferencesFromResource(R.xml.preferences2, rootKey)
        }
    }
}

res > menu > settings_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_settings"
        android:orderInCategory="100"
        android:title="Settings"
        app:showAsAction="ifRoom" />

</menu>

res > xml > root_preferences.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <Preference
        android:fragment="com.example.PreferencesTest.SettingsActivity2$SettingsFragment"
        android:title="Title"
        android:summary="Summary">
        <extra
            android:name="name"
            android:value="preferences2" />
    </Preference>
</PreferenceScreen>

res > xml > preferences2.xml

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <EditTextPreference
        app:key="callNumber"
        app:title="Call Number"
        android:inputType="phone"
        app:useSimpleSummaryProvider="true" />
</PreferenceScreen>

Answer 1

您需要将 android.R.id.home 的默认行为覆盖为 onBackPressed。

class SettingsActivity : AppCompatActivity() {

    ...

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        return when (item.itemId) {
            android.R.id.home -> {
                onBackPressed()
                true
            }
            else -> super.onOptionsItemSelected(item)
        }
    }

    ...

Answer 2

在这里找到了一个很好的完整示例https://github.com/googlearchive/android-preferences

后退按钮在首选项多个屏幕上不起作用

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