[Catalyst] Fix MainSwitchBarPreference NPE when configuration changed

When activity is recreated (due to configuration is changed),
preference screen is created before SettingsActivity sets view layout
and results in NPE. As a workaround, save the states inside
MainSwitchBarPreference to fix the problem.

Bug: 332201912
Flag: EXEMPT library
Test: manual
Change-Id: I052cd0a521dac203a5f58963c550911e7a741e6f

src/com/android/settings/widget/MainSwitchBarPreference.kt

@@ -17,6 +17,8 @@
 package com.android.settings.widget
 
 import android.content.Context
+import android.os.Parcel
+import android.os.Parcelable
 import android.widget.CompoundButton
 import android.widget.CompoundButton.OnCheckedChangeListener
 import androidx.preference.TwoStatePreference
@@ -28,24 +30,30 @@ import com.android.settingslib.widget.MainSwitchBar
 class MainSwitchBarPreference(context: Context, private val metadata: MainSwitchBarMetadata) :
     TwoStatePreference(context), OnCheckedChangeListener, MainSwitchBar.PreChangeListener {
 
-    private val mainSwitchBar: MainSwitchBar = (context as SettingsActivity).switchBar
+    // main switch bar might be null when configuration is just changed
+    private val mainSwitchBar: MainSwitchBar?
+        get() = (context as SettingsActivity).switchBar
 
     override fun setTitle(title: CharSequence?) {
-        mainSwitchBar.setTitle(title)
+        mainSwitchBar?.setTitle(title)
+        super.setTitle(title)
     }
 
     override fun setSummary(summary: CharSequence?) {
-        mainSwitchBar.setSummary(summary)
+        mainSwitchBar?.setSummary(summary)
+        super.setSummary(summary)
     }
 
     override fun setEnabled(enabled: Boolean) {
-        mainSwitchBar.isEnabled = enabled
+        mainSwitchBar?.isEnabled = enabled
+        super.setEnabled(enabled)
     }
 
     // Preference.setVisible is final, we cannot override it
     fun updateVisibility() {
         // always make preference invisible, the UI visibility is reflected on MainSwitchBar
         isVisible = false
+        val mainSwitchBar = mainSwitchBar ?: return
         if ((metadata as? PreferenceAvailabilityProvider)?.isAvailable(context) != false) {
             mainSwitchBar.show()
         } else {
@@ -54,6 +62,7 @@ class MainSwitchBarPreference(context: Context, private val metadata: MainSwitch
     }
 
     override fun setChecked(checked: Boolean) {
+        val mainSwitchBar = mainSwitchBar ?: return
         // remove listener to update UI only
         mainSwitchBar.removeOnSwitchChangeListener(this)
         mainSwitchBar.isChecked = checked
@@ -62,6 +71,7 @@ class MainSwitchBarPreference(context: Context, private val metadata: MainSwitch
 
     override fun onAttached() {
         super.onAttached()
+        val mainSwitchBar = mainSwitchBar!!
         mainSwitchBar.setPreChangeListener(this)
         mainSwitchBar.addOnSwitchChangeListener(this)
     }
@@ -76,8 +86,65 @@ class MainSwitchBarPreference(context: Context, private val metadata: MainSwitch
     }
 
     override fun onDetached() {
+        val mainSwitchBar = mainSwitchBar!!
         mainSwitchBar.removeOnSwitchChangeListener(this)
         mainSwitchBar.setPreChangeListener(null)
         super.onDetached()
     }
+
+    override fun onSaveInstanceState(): Parcelable =
+        SavedState(super.onSaveInstanceState()!!).also {
+            it.isEnabled = isEnabled
+            it.title = title
+            it.summary = summary
+            it.mainSwitchBarState = mainSwitchBar?.onSaveInstanceState()
+        }
+
+    override fun onRestoreInstanceState(state: Parcelable?) {
+        val savedState = state as SavedState
+        super.onRestoreInstanceState(savedState.superState)
+        isEnabled = savedState.isEnabled
+        title = savedState.title
+        summary = savedState.summary
+        mainSwitchBar?.onRestoreInstanceState(savedState.mainSwitchBarState!!)
+    }
+
+    private class SavedState : BaseSavedState {
+        var isEnabled: Boolean = false
+        var title: CharSequence? = null
+        var summary: CharSequence? = null
+        var mainSwitchBarState: Parcelable? = null
+
+        constructor(source: Parcel) : super(source) {
+            isEnabled = source.readBoolean()
+            title = source.readCharSequence()
+            summary = source.readCharSequence()
+            val stateClass = MainSwitchBar.SavedState::class.java
+            mainSwitchBarState = source.readParcelable(stateClass.classLoader, stateClass)
+        }
+
+        constructor(superState: Parcelable) : super(superState)
+
+        override fun writeToParcel(dest: Parcel, flags: Int) {
+            super.writeToParcel(dest, flags)
+            dest.writeBoolean(isEnabled)
+            dest.writeCharSequence(title)
+            dest.writeCharSequence(summary)
+            dest.writeParcelable(mainSwitchBarState, flags)
+        }
+
+        companion object {
+            @JvmField
+            val CREATOR: Parcelable.Creator<SavedState> =
+                object : Parcelable.Creator<SavedState> {
+                    override fun createFromParcel(parcel: Parcel): SavedState {
+                        return SavedState(parcel)
+                    }
+
+                    override fun newArray(size: Int): Array<SavedState?> {
+                        return arrayOfNulls(size)
+                    }
+                }
+        }
+    }
 }