Back button not working on Preferences multiple screens - android-studio

Question

I am trying to implement preferences using multiple screens. The action bar back button only returns to MainActivity even for sub preference screens. For example, I have a root preference screen and then a sub reference screen. The back button on the root preference screen goes back to the main activity as expected. But the back button on the sub reference screen also goes back to the main activity rather than the root preference screen. Below is a code dump because I'm not sure what I am doing wrong. Thanks.
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

You need to override the default behavior of android.R.id.home to 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

Found a good complete example here https://github.com/googlearchive/android-preferences