我已经多次问过这个类似的问题，并且我试图找出解决方案超过2周。是的，我知道有多个类似的问题，但我之所以问的原因是因为堆栈流量的解决方案都没有工作。我是Android开发的初学者，因此我请你帮助我解决这个问题。我几乎放弃了我的项目。
应用如何工作
App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片视图的形式显示数据。用户可以点击卡片，点击该卡片即可启动新活动（REFERENCE ACTIVITY）。点击卡的数据在第二个活动中加载。这里用户可以执行UPDATE或DELETE功能。
问题
问题是我必须重新启动我的应用只是为了看到注释中的更改。例如，如果我在第二个活动中创建一个注释并返回主活动，则在重新启动应用程序之前，该CREATED注释不可见。更新或删除备注时也是如此。更改仅在重新启动应用时发生。
到目前为止我尝试过的...
----- CODES -----
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，我知道很难通过某些代码。我试图解决它很多次，整天坐着试图解决它仍然没有运气。我请你帮我解决这个问题。如果你使用Java，我不在乎，我只需要一种解决方法。
像这样在AndroidManifest.xml文件中声明您的MainActivity。
android:launchMode="singleTask"
在完成'ReferenceActivity'之前（即调用finish（）），对你的'MainActivity'进行Intent调用。另外，在'MainActivity'中覆盖'onNewIntent（）'方法。
@Override
protected void onNewIntent(Intent intent)
在'onNewIntent（）'方法中，再次加载数据，就像你在'onStart（）'和'onRestart（）'中一样。
解释，我们正在做的是在Activity Stack中添加一个'MainActivity'的引用，所以每当对'MainActivity'进行intent调用而不是创建多个引用时，它只需创建一个引用并每次调用newIntentMethod。
希望，这将解决您的问题。