RecyclerView在插入和更新时未更新

Question

问题-我有两个活动。第一个活动用于以卡视图的形式显示所有数据。单击第二项活动可加载相应卡片视图的特定数据。用户可以从第二个活动中删除/更新已加载的数据，不仅如此，还可以创建新数据。

每次我尝试创建或更新“便笺”时，都必须重新启动整个应用程序才能看到回收者视图中的更改。但是，当我删除便笺时，由于已经看到更改，因此不必重启应用程序。 如何如何解决？

我尝试过的- 1-将读取数据并绑定到适配器的代码复制到onRestart（）方法。没有变化。

2-在几乎所有可能适用的地方都称为 notifyDataSetChanged（）。

主要活动

class MainActivity : AppCompatActivity() {

var dbHandler: PediaDatabase? = null
var adapter: PediaAdapter? = null
var layoutManager: RecyclerView.LayoutManager? = null

var list: ArrayList<UserNotes>? = ArrayList()
var listItems: ArrayList<UserNotes>? = ArrayList()

val PREFS_NAME: String = "MYPREFS"
var myPrefs: SharedPreferences? = null
var first_run: Boolean = true

val REQUEST_CODE: Int = 1


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

    showOneTimeMessage()
     invalidateOptionsMenu()

    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
        window.navigationBarColor = Color.BLACK
}


override fun onStart() {
    super.onStart()


    dbHandler = PediaDatabase(this)

    adapter = PediaAdapter(this, listItems!!)
    layoutManager = LinearLayoutManager(this)


    recyclerViewID.adapter = adapter
    recyclerViewID.layoutManager = layoutManager



    list = dbHandler!!.readAllNotes()

    for(reader in list!!.iterator())
    {
        var note = UserNotes()

        note.noteTitle = reader.noteTitle
        note.noteText = reader.noteText
        note.noteID = reader.noteID
        note.noteDate = reader.noteDate

        listItems!!.add(note)
    }

    adapter!!.notifyItemRangeChanged(0, adapter!!.getItemCount());
    adapter!!.notifyDataSetChanged()



    if(dbHandler!!.totalNotes() == 0) {
        recyclerViewID.visibility = View.GONE
    }
    else{
        recyclerViewID.visibility = View.VISIBLE
        showWhenEmptyID.visibility = View.GONE
    }

}


override fun onRestart() {
    super.onRestart()

    var tempData: SharedPreferences = getSharedPreferences(PREFS_NAME,0) //fetch data

    if(tempData.contains("updated")) {

        Log.d("UPDATEDLOL", "TRUE")
        if (tempData.getBoolean("updated", false) == true)
        {

            adapter!!.notifyItemChanged(cardID)
            adapter!!.notifyDataSetChanged()
            recreate()

            sharedPrefs = getSharedPreferences(PREFS_SHARE, 0)
            val editor: SharedPreferences.Editor = (sharedPrefs as SharedPreferences).edit()
            editor.putBoolean("updated", false).commit()
        }
    }


    if(tempData.contains("deleted")) {
        if (tempData.getBoolean("deleted", false) == true)
        {
            //adapPos takes adapter position from Adapter class
            listItems!!.removeAt(cardID)
            adapter!!.notifyItemRemoved(cardID)
            adapter!!.notifyItemRangeChanged(cardID, listItems!!.size)
            adapter!!.notifyDataSetChanged()

            recyclerViewID.removeAllViews()

            sharedPrefs = getSharedPreferences(PREFS_SHARE, 0)
            var editor: SharedPreferences.Editor = (sharedPrefs as SharedPreferences).edit()
            editor.putBoolean("deleted", false).commit() //TODO CHANGED HERE
        }
    }



    if(tempData.contains("created")) {
        if (tempData.getBoolean("created", false) == true)
        {
            adapter!!.notifyItemInserted(cardID)
            adapter!!.notifyItemRangeInserted(cardID, listItems!!.size)
            adapter!!.notifyDataSetChanged()
            recyclerViewID.invalidate()
            recyclerViewID.removeAllViews()

            sharedPrefs = getSharedPreferences(PREFS_SHARE, 0)
            val editor: SharedPreferences.Editor = (sharedPrefs as SharedPreferences).edit()
            editor.putBoolean("created", false).commit()
        }
    }
}


override fun onCreateOptionsMenu(menu: Menu?): Boolean {
    menuInflater.inflate(R.menu.top_menu, menu)

    val item = menu!!.findItem(R.id.delete_note_menu)
    item.setVisible(false)
    return true
}

override fun onOptionsItemSelected(item: MenuItem?): Boolean {

    if(item!!.itemId == R.id.add_note_menu){

        var isNewNote = Intent(this, ReferenceActivity::class.java)
        isNewNote.putExtra("isNewNote", true)


        startActivityForResult(isNewNote, REQUEST_CODE)
    }


    if(item!!.itemId == R.id.delete_note_menu)
    {

        Toast.makeText(this,"DELETED", Toast.LENGTH_SHORT).show()
    }

    return super.onOptionsItemSelected(item)
}

override fun startActivityForResult(intent: Intent?, requestCode: Int) {
    super.startActivityForResult(intent, requestCode)

}

private fun showOneTimeMessage()
{
    var data: SharedPreferences = getSharedPreferences(PREFS_NAME, 0)
    if(data.contains("isShown"))
    {
        first_run = data.getBoolean("isShown", true)
    }


    Log.d("FIRST_RUN", first_run.toString())

    if(first_run) {



        val oneTimeMsg = SweetAlertDialog(this)
        oneTimeMsg.setTitleText("Hey there!")
        oneTimeMsg.setContentText("Thank you for downloading! Please don`t forget to rate our app :)").show()

        oneTimeMsg.setConfirmClickListener(object : SweetAlertDialog.OnSweetClickListener {

            override fun onClick(sweetAlertDialog: SweetAlertDialog?) {
                oneTimeMsg.dismissWithAnimation()
            }
        }).show()


        myPrefs = getSharedPreferences(PREFS_NAME, 0)
        var editor: SharedPreferences.Editor = (myPrefs as SharedPreferences).edit()
        editor.putBoolean("isShown", false)
        editor.commit()



    }
}

第二活动

class ReferenceActivity : AppCompatActivity() {

var dbHandler: PediaDatabase? = null
var note = UserNotes()

var existingNote = UserNotes()
var noteExisted: Boolean = false
var cardAdapterPos: Int? = null

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

    getSupportActionBar()!!.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
     getSupportActionBar()!!.setCustomView(R.layout.custom_toolbar);
      val dateTxtView = findViewById<View>(resources.getIdentifier("action_bar_title", "id", packageName)) as TextView


    overridePendingTransition(R.anim.slide_in, R.anim.slide_out);

    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
        window.navigationBarColor = Color.BLACK


    dbHandler = PediaDatabase(this)
    var data = intent
    var isNewNote = intent


    if(isNewNote != null)
        if(isNewNote.extras.getBoolean("isNewNote") != true)
        {
            getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_HIDDEN)

            if(data != null)
            {
                noteExisted = true


                this.cardAdapterPos = data.extras.getInt("cardPosition")
                cardID = data.extras.getInt("cardID")


                existingNote = dbHandler!!.readNote(cardID)

                refTitleID.setText(existingNote.noteTitle, TextView.BufferType.EDITABLE)
                refTextID.setText(existingNote.noteText, TextView.BufferType.EDITABLE)
                dateTxtView.text = existingNote.noteDate.toString()
            }
        }else{
            dateTxtView.text = "New note"
        }
}

override fun onStop() {
    super.onStop()


    var title: String = refTitleID.text.toString().trim()
    var text: String = refTextID.text.toString().trim()

    if(existingNote.noteText == text && existingNote.noteTitle == title)
        finish()

    if(noteExisted)
    {
        if(TextUtils.isEmpty(title))
            title = "No title"


        existingNote.noteTitle = title
        existingNote.noteText = text
       // existingNote.noteDate = System.currentTimeMillis().toString() //TODO TRY THIS


        dbHandler!!.updateNote(existingNote)

        //TODO BACK TO MAIN DATA HERE!!!!

        sharedPrefs = getSharedPreferences(PREFS_SHARE, 0)
        val share_editor: SharedPreferences.Editor = (sharedPrefs as SharedPreferences).edit()
        share_editor.putBoolean("updated", true).commit()


        finish()

    }
    else
    {
        if(TextUtils.isEmpty(title) && TextUtils.isEmpty(text))
        {
            finish()
        }
        else
        {
            if(TextUtils.isEmpty(title))
                title = "No title"

            note.noteTitle = title
            note.noteText = text



            dbHandler!!.createNote(note)


            sharedPrefs = getSharedPreferences(PREFS_SHARE,0)
            val editor: SharedPreferences.Editor = (sharedPrefs as SharedPreferences).edit()
            editor.putBoolean("created",true).commit()


            finish()

        }
    }
}


override fun onCreateOptionsMenu(menu: Menu?): Boolean {

    menuInflater.inflate(R.menu.top_menu, menu)
    val addItem: MenuItem = menu!!.findItem(R.id.add_note_menu)
    val delItem:MenuItem = menu.findItem(R.id.delete_note_menu)


    addItem.setVisible(false)
    delItem.setVisible(false)

    if(noteExisted)
        delItem.setVisible(true)

    return true
}

override fun onOptionsItemSelected(item: MenuItem?): Boolean {

    if(item!!.itemId == R.id.delete_note_menu)
    {
        val dialogMsg = SweetAlertDialog(this, SweetAlertDialog.WARNING_TYPE)
        dialogMsg.setTitleText("Are you sure?")
        dialogMsg.setContentText("You won`t be able to recover this note!")
        dialogMsg.setConfirmText("Yes,delete it!")

        dialogMsg.setConfirmClickListener(object: SweetAlertDialog.OnSweetClickListener {

            override fun onClick(sweetAlertDialog: SweetAlertDialog?) {
                dialogMsg.dismissWithAnimation()

                dbHandler!!.deleteNote(cardID)

                sharedPrefs = getSharedPreferences(PREFS_SHARE,0)

                //TODO HANDLES BACKGROUND BROADCASTING
                val editor: SharedPreferences.Editor = (sharedPrefs as SharedPreferences).edit()
                editor.putBoolean("deleted", true).commit()


                var successMsg = SweetAlertDialog(sweetAlertDialog!!.context, SweetAlertDialog.SUCCESS_TYPE)
                successMsg.setTitleText("Note deleted!")
                successMsg.setContentText("So long,note").show()
                successMsg.setCancelable(false)

                //TODO Disable 'OK' button on successMsg dialogbox

                Handler().postDelayed({
                    successMsg.dismissWithAnimation()
                    finish()
                }, 1200)

            }
        }).show()

    }
    return super.onOptionsItemSelected(item)
}

}