问题描述
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。
我想知道我可以用什么来存储 Kotlin 的值,我看过使用 firebase 的教程,但没有我能看到的与 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存储价值,因为它会是首选
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 0,3 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(),Toast.LENGTH_LONG).show()
}
private fun condition5(){
Toast.makeText(getApplicationContext(),Toast.LENGTH_LONG).show()
}
private fun condition6(){
Toast.makeText(getApplicationContext(),Toast.LENGTH_LONG).show()
}
private fun condition7(){
Toast.makeText(getApplicationContext(),Toast.LENGTH_LONG).show()
}
private fun condition8(){
Toast.makeText(getApplicationContext(),Toast.LENGTH_LONG).show()
}
private fun condition9(){
Toast.makeText(getApplicationContext(),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)
}
解决方法
我猜你是说本地?
SharedPreferences 是要走的路,看来你的还没有工作/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"
}
然后在使用之前定义该首选项变量(就像您已经使用 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
嗯。 Android 中有很多不同的数据存储方式,各有优缺点。
FireBase 可能适合远程存储数据。 Room 可能适合将其存储在本地 (Android Room) 或者,如果它是简单的数据(如用户首选项或设置),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。 您可能想通读其中的一些内容:Android Topics - Data 祝你好运:-)
附言您可能想查看 Kotlin 中的“when”: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()
}
就像..
when(statusFilter.selectedItemPosition) {
1 -> condition1()
2 -> condition2()
3 -> condition3()
... etc ...
}
打字少得多:-)