回收站视图未正确更新

Question

我已经多次问过类似的问题，并且已经超过2个星期了，我一直在努力寻求解决方案。是的，我知道有多个类似的问题，但是我问的原因是因为所有的解决方案都无法正常工作。我是Android开发中的初学者，因此请您请帮助我解决这个问题。我几乎放弃了我的项目。

应用程序的工作方式

应用有两项活动。主要活动用于使用从 SQ Lite DB 加载的回收站视图以卡视图的形式显示数据。用户可以单击卡，单击该卡将启动新的活动（参考活动）。点击的卡片数据被加载到第二活动中。用户可以在此处执行 UPDATE 或 Delete 功能。

问题

问题是我必须重新启动我的应用程序才能看到笔记中的更改。例如，如果我在第二个活动中创建便笺并返回至主要活动，则在重新启动应用程序之前，该已创建便笺将不可见。更新或删除便笺时也是如此。仅在重新启动应用程序时发生更改。

到目前为止我已经尝试过...

• 在MAIN活动的onRestart（）中称为notifyDataSetChanged（）。

• 在onRestart（）中首先加载回收者视图项的整个加载

• 尝试使用新数据更新适配器

-----编码-----

主要活动

class MainActivity : AppCompatActivity() {

var dbHandler: PediaDatabase = PediaDatabase(this)
var adapter: PediaAdapter? = null
var newAdapter: PediaAdapter? = null
var layoutManager: RecyclerView.LayoutManager? = null
var list: ArrayList<UserNotes>? = ArrayList()
var listItems: ArrayList<UserNotes>? = ArrayList()
var updatedList: ArrayList<UserNotes> = ArrayList()
var tempList: ArrayList<UserNotes>? = null
var myPrefs: SharedPreferences? = null
var first_run: Boolean = true
var isCreated: Boolean = false
var isUpdated: Boolean = false
var isDeleted: Boolean = false
var isReturning: Boolean = false

var updatedTitle: String? = null
var updatedText: String? = null

val PREFS_NAME: String = "MYPREFS"
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 onRestart() {
    super.onRestart()

    if(isUpdated)
    {
        recyclerViewID.recycledViewPool.clear()
        var test = listItems!![adapPos]
        test.noteTitle = updatedTitle
        test.noteText = updatedText
        listItems!!.set(adapPos, test)
        adapter!!.notifyItemChanged(adapPos)

        isUpdated = false
    }
}


override fun onStart() {
    super.onStart()

    if(isReturning)
    {
        adapter!!.updateResults(this.listItems!!)
        adapter!!.notifyDataSetChanged()
    }

    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!!.notifyDataSetChanged()


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





override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)

    if(requestCode == REQUEST_CODE)
        if(resultCode == Activity.RESULT_OK)
        {
            //isCreated = data!!.extras!!.getBoolean("isCreated")

            updatedTitle = data!!.extras.getString("updatedTitle")
            updatedText = data!!.extras.getString("updatedText")

            isReturning = data.extras!!.getBoolean("returningBack")
           // isUpdated = data.extras!!.getBoolean("isUpdated")
        }
}


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){

        isNewNote = true
        startActivity(Intent(this, ReferenceActivity::class.java))
    }

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

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

    return super.onOptionsItemSelected(item)
}

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()

    }
}

参考活动

class ReferenceActivity : AppCompatActivity() {

var dbHandler: PediaDatabase? = null
var note = 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)
    val data = intent
        if(isNewNote != true/*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)

        var dataCreate = this.intent
        dataCreate.putExtra("isUpdated", true)
        dataCreate.putExtra("updatedTitle", title)
        dataCreate.putExtra("updatedText",text)
        dataCreate.putExtra("returningBack", true)
        setResult(Activity.RESULT_OK, dataCreate)


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

            note.noteTitle = title
            note.noteText = text
            note.noteDate = System.currentTimeMillis().toString()
           // note.noteID =

            dbHandler!!.createNote(note)

            var dataCreate = this.intent
            dataCreate.putExtra("isCreated", true)
            dataCreate.putExtra("returningBack", true)
            setResult(Activity.RESULT_OK, dataCreate)

            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)


                val 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)
}

适配器

class PediaAdapter(private val context: Context,
               private var noteslist: ArrayList<UserNotes>): RecyclerView.Adapter<PediaAdapter.ViewHolder>() {

override fun onCreateViewHolder(p0: ViewGroup, p1: Int): ViewHolder
{
    val view = LayoutInflater.from(context).inflate(R.layout.list_row,p0,false)

    return ViewHolder(view, noteslist)
}

override fun getItemCount(): Int
{
    return noteslist.size
}

override fun onBindViewHolder(p0: ViewHolder, p1: Int)
{
    p0.bindItems(noteslist[p1])
}

inner class ViewHolder(itemView: View, list: ArrayList<UserNotes>): RecyclerView.ViewHolder(itemView), View.OnClickListener
{
    private var noteTitle = itemView.findViewById(R.id.listTitleID) as TextView
    private var noteText = itemView.findViewById(R.id.listTextID) as TextView

    var mList = list


    init
    {
        itemView.setOnClickListener(this)
    }

    fun bindItems(note: UserNotes)
    {
        //var id = note.noteID
        noteTitle.text = note.noteTitle
        noteText.text = note.noteText
    }

    override fun onClick(v: View?)
    {

        var mPosition: Int =  adapterPosition //For forwarding position to ref activity
        var note = mList[mPosition]
        adapPos = adapterPosition


        var cardID = Intent(itemView.context, ReferenceActivity::class.java)
        cardID.putExtra("cardPosition", mPosition)
        cardID.putExtra("cardID", note.noteID) //TODO THIS IS FETCHING NOTE_ID VALUES FROM DB

        Toast.makeText(itemView.context, "card id = " + note.noteID, Toast.LENGTH_SHORT).show()

        itemView.context.startActivity(cardID)
    }

}

fun updateResults(items: ArrayList<UserNotes>)
{
    this.noteslist = items
}

是的，我知道很难通过某人的代码进行操作。我整天试图修复它，试图解决它，但仍然没有运气。我请您帮助我。我不在乎您是否使用Java，我只需要一种方法来修复它。

Answer 1

像这样在AndroidManifest.xml文件中声明您的MainActivity。

android:launchMode="singleTask"

在完成“ ReferenceActivity”（即调用finish（））之前，请对您的“ MainActivity”进行Intent调用。另外，请在“ MainActivity”内部覆盖“ onNewIntent（）”方法。

@Override
protected void onNewIntent(Intent intent)

在“ onNewIntent（）”方法中，像在“ onStart（）”和“ onRestart（）”中所做的那样，再次加载数据。

说明，我们正在做的是在“活动堆栈”中添加“ MainActivity”的单个引用，因此，只要对“ MainActivity”进行意向调用而不是创建多个引用，它只需创建一个引用并每次都调用newIntentMethod

希望能解决您的问题。