您如何存储用户输入数据中的值？

Question

我创建了一个微调器来显示用户可以选择的类别，当它被选中时，我希望将选项保存在某处。

我想知道我可以使用什么来存储 Kotlin 的值，我看过使用 firebase 的教程，但没有看到与 Kotlin 相关的教程，firebase 是您可以使用的唯一存储还是有更简单的方法将值存储为首选

activity_main.xml

<Spinner
                 android:layout_width="match_parent"
                 android:layout_height="75dp"
                 android:id="@+id/statusFilter"
                 android:layout_gravity="center" />

  <Button
                    android:id="@+id/btnAdd"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_margin="16dp"
                    android:paddingTop="8dp"
                    android:paddingBottom="8dp"
                    android:stateListAnimator="@null"
                    android:onClick="btnAdd"
                    android:text="@string/button_addLetter"
                    android:background="@color/design_default_color_secondary_variant"
                    android:textColor="@color/design_default_color_on_primary"
                    android:textSize="16sp" />

主要活动

class NewsActivity : AppCompatActivity(), AnkoLogger, DatePickerDialog.OnDateSetListener, TimePickerDialog.OnTimeSetListener {

    var letter = NewsItemModel()
    lateinit var app : MainApp
    var edit = false
    val IMAGE_REQUEST = 1

 override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_letter)
        app = application as MainApp
   


 val dropDownList = arrayOf("Latest", "Coronavirus Updates", "Crime", "Traffic and Travel", "Business", "Politics", "Weather", "Education", "Health")

        val adapter = ArrayAdapter(this, android.R.layout.simple_spinner_item, dropDownList)
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_item)
        statusFilter.adapter = adapter
        statusFilter.onItemSelectedListener = object : AdapterView.OnItemSelectedListener{
   val preferences = getSharedPreferences("sharedPrefs", Context.MODE_PRIVATE)

            override fun onNothingSelected(parent: AdapterView<*>?) {
            }

            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
                if(statusFilter.selectedItemPosition == 1){
                    preferences.edit().putInt("POSITION_KEY",1).apply() //Puts 0, 1,2,3 with key "POSITION_KEY"
                }

                if(statusFilter.selectedItemPosition == 2){
                    preferences.edit().putInt("POSITION_KEY",2).apply() //Puts 0, 1,2,3 with key "POSITION_KEY"
                }
                }
                if(statusFilter.selectedItemPosition == 3){
                    condition3()
                }
                if(statusFilter.selectedItemPosition == 4){
                    condition4()
                }
                if(statusFilter.selectedItemPosition == 5){
                    condition5()
                }
                if(statusFilter.selectedItemPosition == 6){
                    condition6()
                }
                if(statusFilter.selectedItemPosition == 7){
                    condition7()
                }
                if(statusFilter.selectedItemPosition == 8){
                    condition8()
                }
                if(statusFilter.selectedItemPosition == 9){
                    condition9()
                }
            }

        private fun condition1(){
                preferences.getInt("POSITION_KEY",1)
            }
            private fun condition2(){
                preferences.getInt("POSITION_KEY",2)
            }
            private fun condition3(){
                Toast.makeText(getApplicationContext(), "selected Item: " + statusFilter.selectedItem, Toast.LENGTH_LONG).show()
            }
            private fun condition4(){
                Toast.makeText(getApplicationContext(), "selected Item: " + statusFilter.selectedItem, Toast.LENGTH_LONG).show()
            }
            private fun condition5(){
                Toast.makeText(getApplicationContext(), "selected Item: " + statusFilter.selectedItem, Toast.LENGTH_LONG).show()
            }
            private fun condition6(){
                Toast.makeText(getApplicationContext(), "selected Item: " + statusFilter.selectedItem, Toast.LENGTH_LONG).show()
            }
            private fun condition7(){
                Toast.makeText(getApplicationContext(), "selected Item: " + statusFilter.selectedItem, Toast.LENGTH_LONG).show()
            }
            private fun condition8(){
                Toast.makeText(getApplicationContext(), "selected Item: " + statusFilter.selectedItem, Toast.LENGTH_LONG).show()
            }
            private fun condition9(){
                Toast.makeText(getApplicationContext(), "selected Item: " + statusFilter.selectedItem, Toast.LENGTH_LONG).show()
            }




fun btnAdd(view: View) {
        val pref = getPreferences(Context.MODE_PRIVATE)
        val editor = pref.edit()

        editor.putString("SELECTION", statusFilter.toString())

        editor.commit()

        Toast.makeText(applicationContext, "Saved test1", Toast.LENGTH_LONG).show()
    }

 val pref = getPreferences(Context.MODE_PRIVATE)
        val SELECTION = pref.getString("SELECTION", "")
        statusFilter(SELECTION)
        }

Answer 1

我假设你的意思是本地？

SharedPreferences 是要走的路，你的似乎还没有工作/实施： https://developer.android.com/training/data-storage/shared-preferences

您可能只关心选择的位置，因此将所有条件替换为：

override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
      preferences.edit().putInt("POSITION_KEY",position).apply() //Puts 0, 1,2,3 with key "POSITION_KEY"
}

然后在使用它之前定义该首选项变量（就像您已经对 getPreferences 所做的那样，请参阅链接）

然后您可以使用 preferences.getInt("POSITION_KEY",0) 检索它，其中 0 是尚未定义/放置键时的默认值

Answer 2

嗯。在 Android 中存储数据的方式有很多种，各有优劣。

FireBase 可能适合远程存储数据。 Room 可能适合在本地存储它 (Android Room) 或者，如果它是简单的数据（例如用户偏好或设置），那么 UserPreferences 可能就是您想要的 (Android - Key Value Data)

Google 提供了相当多的信息，但有时很难知道要查找什么。 您可能想阅读其中的一些内容：Android Topics - Data 祝你好运:-)

附：您可能想查看 Kotlin 中的“何时”：Try When

然后你可以重写

                if(statusFilter.selectedItemPosition == 1){
                condition1()
            }
            if(statusFilter.selectedItemPosition == 2){
                condition2()
            }
            if(statusFilter.selectedItemPosition == 3){
                condition3()
            }
            if(statusFilter.selectedItemPosition == 4){
                condition4()
            }
            if(statusFilter.selectedItemPosition == 5){
                condition5()
            }

有点像..

when(statusFilter.selectedItemPosition) {
   1 -> condition1()
   2 -> condition2()
   3 -> condition3()
... etc ...
}

少打字:-)