【发布时间】：2020-04-10 12:10:36
【问题描述】：
我正在尝试制作一个 Todo 应用程序，我已经完成了 Room 部分并且能够存储数据现在我想以 Recycler View 的形式显示数据，但我不知道如何编写与其对应的适配器类.我在不同的网站上寻找它，但从未得到任何满意的答案。
**TodoFragViewModel.kt""
class TodofragViewModel(
val database: TodoDao, applicaltion: Application
): AndroidViewModel(applicaltion) {
// TODO: Implement the ViewModel
/**
* viewModelJob allows us to cancel all coroutines started by this ViewModel.
*/
private var viewModelJob = Job()
/**All coroutines can be cancelled by viewmodelJob.cancel() and Dispatcher.main is byDefault choice
*/
private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)
private val currenctTodo = MutableLiveData<Todo?>()
private val allTodo = database.getAllTodo()
init{
intializeThisTodo()
}
private fun intializeThisTodo(){
uiScope.launch {
currenctTodo.value=getFromDatabase()
}
}
private suspend fun getFromDatabase(): Todo? {
return withContext(Dispatchers.IO){
val info =database.getCurrentTodo()
info
}
}
private suspend fun insert(thisTodo: Todo) {
withContext(Dispatchers.IO) {
database.insert(thisTodo)
Log.i("Database","${database.getCurrentTodo()?.description} and ${database.getCurrentTodo()?.time}")
}
}
fun onAdded(time:String,description:String) {
uiScope.launch {
val thisTodo = Todo(time,description)
insert(thisTodo)
currenctTodo.value=getFromDatabase()
}
}
/**
* Called when the ViewModel is dismantled.
* At this point, we want to cancel all coroutines;
* otherwise we end up with processes that have nowhere to return to
* using memory and resources.
*/
override fun onCleared() {
super.onCleared()
viewModelJob.cancel()
}
}
todo_recycler_view
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent" android:layout_height="wrap_content">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/date_text"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="16dp"
android:text="TextView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/todo_description"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="16dp"
android:text="TextView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/date_text" />
</androidx.constraintlayout.widget.ConstraintLayout>
TodoFrag.kt
class todofrag : Fragment() {
companion object {
fun newInstance() = todofrag()
}
private lateinit var viewModel: TodofragViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.todofrag_fragment, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
val application = requireNotNull(this.activity).application
val dataSource= TodoDatabase.getInstance(application)?.InformationDatabaseDao
val viewModelFactory = dataSource?.let { TodoViewModelFactory(it, application) }
val viewModel=ViewModelProviders.of(this,viewModelFactory).get(TodofragViewModel::class.java)
add_button.setOnClickListener{
val currentDate: String = SimpleDateFormat("dd/MM/yyyy", Locale.getDefault()).format(Date())
val currentTime: String = SimpleDateFormat("HH:mm:ss", Locale.getDefault()).format(Date())
val time:String="${currentDate} \n ${currentTime}"
viewModel.onAdded(time,todo_text.text.toString())
}
}
}
如果添加了任何其他文件，请告诉我。顺便说一句，我尝试使用卡片视图以使其看起来不错。
【问题讨论】：
标签： kotlin android-room android-recyclerview