ListView的最新更新

Question

我让listView使用Realm来填充这些项。列表视图是宝永章的SwipeMenuListView。我有一个问题，listView没有立即更新。相反，当我存在应用程序并返回时，列表将反映新的更改。

我使用AlertDialog提示用户更新选定的参数，这些参数将在listView中更新。

我使用RealmHelper类填充listView ArrayAdapter

下面是帮助器类(RealmHelper)的代码：

fun readAll(): ArrayList<User> {
   val finalList = ArrayList<User>()
   val listOfUsers = mRealm.where(User::class.java).findAll()

   finalList += listOfUsers

   return finalList
}

这是主要的活动类代码

class Users: AppCompatActivity() {

    private lateinit var realm: Realm

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

        realm = Realm.getDefaultInstance()
        val helper = RealmHelper(realm)
        val users = helper.readAll()
        val mAdapter = MyAdapter(this, users)
        listView.adapter = mAdapter
   }
}

这是实际发生更新的主要代码：

listView.setOnMenuItemClickListener(SwipeMenuListView.OnMenuItemClickListener { position, menu, index ->

            when (index) {
                0 -> {
                    val alert = AlertDialog.Builder(this@Users).create()
                    alert.setTitle("Update Car Details")
                    val all = realm.where(User::class.java).findAll()
                    val selectedCar = all[position]!!
                    val name = EditText(this@Users)
                    name.hint = "Nickname"
                    val carNumber = EditText(this@Users)
                    carNumber.hint = "Car Number"
                    val duration = EditText(this@Users)
                    duration.hint = "Duration (hr)"
                    val code = EditText(this@Emirates)
                    code.hint = "Code"

                    name.setText(selectedCar.nickName)
                    carNumber.setText(selectedCar.plateNum)
                    duration.setText(selectedCar.duration)
                    code.setText(selectedCar.code)

                    val layout = LinearLayout(this)
                    layout.orientation = LinearLayout.VERTICAL
                    layout.addView(name)
                    layout.addView(carNumber)
                    layout.addView(duration)
                    layout.addView(code)

                    alert.setView(layout, 60, 0,60,0)

                    alert.setButton(AlertDialog.BUTTON_POSITIVE,"Update", object :DialogInterface.OnClickListener {
                        override fun onClick(dialog: DialogInterface?, which: Int) {

                            realm.beginTransaction()
                            selectedCar.code = code.text.toString()
                            selectedCar.plateNum = carNumber.text.toString()
                            selectedCar.duration = duration.text.toString()
                            selectedCar.nickName = name.text.toString()
                            emirates[position] = selectedCar
                            realm.commitTransaction()
                            mAdapter.notifyDataSetChanged()
                            Toast.makeText(this@Users, "${mAdapter.notifyDataSetChanged()} called", Toast.LENGTH_LONG).show()

                        }
                    })

                    alert.setButton(AlertDialog.BUTTON_NEGATIVE, "Cancel", object : DialogInterface.OnClickListener {
                        override fun onClick(dialog: DialogInterface?, which: Int) {
                            dialog?.dismiss()
                        }

                    })

                    alert.show()
                }
                1 -> {
                    realm.beginTransaction()
                    val all = realm.where(User::class.java).findAll()
                    val selectedUser = all[position]
                    selectedUser?.deleteFromRealm()
                    emirates.removeAt(position)
                    realm.commitTransaction()
                    mAdapter.notifyDataSetChanged()
                }
                else -> return@OnMenuItemClickListener false
            }

            true
        })

我使用Toast来测试是否调用了mAdapter.notifyDataSetChanged()，并验证了是否调用了它，但似乎listView直到应用程序重新启动后才会更新。

你知道为什么会发生这种行为吗？

注意:这是指向：https://github.com/baoyongzhang/SwipeMenuListView的实际库的链接

Answer 1

notifyDataSetChanged方法的问题在于，它会检测到信息源何时发生更改，但不会检测到何时重新签名。我在使用这种方法时遇到了很多问题，所以我建议在这种情况下不使用notifyDateSetChanged，但您可以使用新的信息源创建一个新的适配器。尝试使用此更改。

alert.setButton(AlertDialog.BUTTON_POSITIVE,"Update", object :DialogInterface.OnClickListener {
                        override fun onClick(dialog: DialogInterface?, which: Int) {

                            realm.beginTransaction()
                            selectedCar.code = code.text.toString()
                            selectedCar.plateNum = carNumber.text.toString()
                            selectedCar.duration = duration.text.toString()
                            selectedCar.nickName = name.text.toString()
                            emirates[position] = selectedCar
                            realm.commitTransaction()
                            val realm = Realm.getDefaultInstance()
                            val helper = RealmHelper(realm)
                            val users = helper.readAll()
                            mAdapter = MyAdapter(this, users)
                            listView.adapter = mAdapter
                            Toast.makeText(this@Users, "${mAdapter.notifyDataSetChanged()} called", Toast.LENGTH_LONG).show()

                        }
                    })

试试这个，我希望它能和你一起工作。