Complete methods

app/build.gradle

@@ -64,6 +64,7 @@ dependencies {
     implementation 'org.ocpsoft.prettytime:prettytime:5.0.1.Final'
     implementation "androidx.core:core-ktx:1.3.2"
     implementation "androidx.appcompat:appcompat:1.3.0"
+    implementation "androidx.preference:preference-ktx:1.1.1"
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.4.2'
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.2'

app/src/main/AndroidManifest.xml

@@ -31,7 +31,8 @@
     <application android:label="@string/ime_name"
                  android:icon="@drawable/icon"
                  android:requestLegacyExternalStorage="true"
-                 android:allowBackup="false" >
+                 android:allowBackup="false"
+                 android:theme="@style/PreferenceTheme">
 
         <service android:name="Trime" android:label="@string/ime_name"
                 android:permission="android.permission.BIND_INPUT_METHOD">
@@ -40,13 +41,21 @@
             </intent-filter>
             <meta-data android:name="android.view.im" android:resource="@xml/method" />
         </service>
-
+        <!--
         <activity android:name="Pref" android:label="@string/ime_name">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
                 <category android:name="android.intent.category.DEFAULT" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
+        </activity> -->
+
+        <activity android:name=".settings.PrefMainActivity" android:label="@string/ime_name">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.DEFAULT" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
         </activity>
     </application>
 </manifest>

app/src/main/java/com/osfans/trime/settings/PrefMainActivity.kt

@@ -4,6 +4,7 @@ import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.Toolbar
 import androidx.fragment.app.Fragment
+import androidx.preference.PreferenceFragmentCompat
 import com.osfans.trime.R
 import com.osfans.trime.databinding.PrefActivityBinding
 
@@ -20,12 +21,43 @@ class PrefMainActivity: AppCompatActivity() {
 
         val toolbar = findViewById<Toolbar>(R.id.toolbar)
         setSupportActionBar(toolbar)
+
+        if (savedInstanceState == null) {
+            loadFragment(PrefFragment())
+        } else {
+            title = savedInstanceState.getCharSequence(FRAGMENT_TAG)
+        }
+        supportFragmentManager.addOnBackStackChangedListener {
+            if (supportFragmentManager.backStackEntryCount == 0) {
+                setTitle(R.string.ime_name)
+            }
+        }
+
+        supportActionBar?.setDisplayHomeAsUpEnabled(true)
     }
-
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        super.onSaveInstanceState(outState)
+        outState.putCharSequence(FRAGMENT_TAG, title)
+    }
+
+    override fun onSupportNavigateUp(): Boolean {
+        if (supportFragmentManager.popBackStackImmediate()) {
+            return true
+        }
+        return super.onSupportNavigateUp()
+    }
+
     private fun loadFragment(fragment: Fragment) {
         supportFragmentManager
             .beginTransaction()
             .replace(binding.preference.id, fragment, FRAGMENT_TAG)
             .commit()
     }
+
+    class PrefFragment : PreferenceFragmentCompat() {
+        override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
+            setPreferencesFromResource(R.xml.prefs, rootKey)
+        }
+    }
 }

app/src/main/res/values/styles.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <style name="PreferenceTheme" parent="Theme.AppCompat.DayNight.NoActionBar">
+        <item name="colorPrimary">@color/colorPrimary</item>
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+        <item name="android:colorAccent" tools:targetApi="lollipop">@color/colorAccent</item>
+    </style>
+</resources>