Android如何实现记事本功能

apply plugin: 'kotlin-kapt'
'''
implementation 'com.google.android.material:material:1.0.0'
 implementation 'de.hdodenhof:circleimageview:3.0.1'
 implementation 'com.android.support.constraint:constraint-layout:1.1.3'
 implementation 'androidx.room:room-runtime:2.1.0'
 implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
 implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.2.0'
 implementation 'androidx.recyclerview:recyclerview:1.0.0'
 kapt "androidx.room:room-compiler:2.1.0"

@Dao
interface NoteDao {


 @Update
 fun updateNote(newNote: Note)

 @Query("select * from Note")
 fun loadAllNotes(): List<Note>

 @Query("select * from Note where title > :title")
 fun loadNotesLongerThan(title:String) : List<Note>

 @Query("select * from Note where id == :id")
 fun loadById(id:Long) :Note

 @Delete
 fun deleteNote(note: Note)

 @Query("delete from Note where title == :title")
 fun deleteNoteByTitle(title: String): Int

 @Insert
 fun insertNote(note: Note)


}

@Database(version = 1, entities = [Note::class])
abstract class AppDatabase: RoomDatabase(){

 abstract fun noteDao() : NoteDao

 companion object{
  //访问实例
  private var instance : AppDatabase? = null

  @Synchronized//同步化
  fun getDatabase(context: Context):AppDatabase{
   instance?.let {
    return it
   }
   return Room.databaseBuilder(context.applicationContext,
   AppDatabase::class.java, "app_database")
    .build().apply {
     instance = this
    }
  }
 }
}

class RecycleItemTouchHelper(private val helperCallback: ItemTouchHelperCallback) :
 ItemTouchHelper.Callback() {

 //设置滑动类型标记
 override fun getMovementFlags(
  recyclerView: RecyclerView,
  viewHolder: RecyclerView.ViewHolder
 ): Int {
  return makeMovementFlags(ItemTouchHelper.UP or ItemTouchHelper.DOWN,
   ItemTouchHelper.END or ItemTouchHelper.START )
 }


 override fun isLongPressDragEnabled(): Boolean {
  return true
 }

 //滑动
 override fun isItemViewSwipeEnabled(): Boolean {
  return true
 }

 //拖拽回调
 override fun onMove(
  recyclerView: RecyclerView,
  viewHolder: RecyclerView.ViewHolder,
  target: RecyclerView.ViewHolder
 ): Boolean {
  helperCallback.onMove(viewHolder.adapterPosition, target.adapterPosition)
  return true
 }

 //滑动
 override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int): Unit {
  helperCallback.onItemDelete(viewHolder.adapterPosition)
 }

 //状态回调
 override fun onSelectedChanged(
  viewHolder: RecyclerView.ViewHolder?,
  actionState: Int
 ) {
  super.onSelectedChanged(viewHolder, actionState)
 }

 interface ItemTouchHelperCallback {
  fun onItemDelete(positon: Int)
  fun onMove(fromPosition: Int, toPosition: Int)
 }


}

//拖拽排序
 override fun onMove(fromPosition: Int, toPosition: Int) {
  val noteDao = AppDatabase.getDatabase(context).noteDao()
   if (fromPosition < toPosition) {
    for (i in fromPosition until toPosition) {
     Collections.swap(noteList, i, i + 1)
     for (i in noteList){
      Log.d("title", i.title)
     }
     Log.d("tag2", fromPosition.toString()+"->"+toPosition)    
    }
   } else {
    for (i in fromPosition downTo toPosition + 1) {
     Collections.swap(noteList, i, i - 1)
    }
   }
  //排序后的数据更新
  thread {
   var templist = noteDao.loadAllNotes().toMutableList()
   for (i in 0 until templist.size){
    templist[i].title = noteList[i].title
    templist[i].content = noteList[i].content
    noteDao.updateNote(templist[i])
   }
  }

  notifyItemMoved(fromPosition, toPosition)

 }

class MyReceiver : BroadcastReceiver() {

 override fun onReceive(context: Context, intent: Intent) {
  // This method is called when the BroadcastReceiver is receiving an Intent broadcast.
  Toast.makeText(context,"You have a task to do!!!", Toast.LENGTH_LONG).show()
 }
}

setBtn.setOnClickListener { view ->
   val c = Calendar.getInstance()
   //调整为中国时区，不然有8小时差比较麻烦
   val tz = TimeZone.getTimeZone("Asia/Shanghai")
   c.timeZone = tz
   //获取当前时间
   if (setHour.text.toString()!=""&&setMin.text.toString()!="") {
    c.set(Calendar.HOUR_OF_DAY, setHour.text.toString().toInt());//小时
    c.set(
     Calendar.MINUTE, setMin.text.toString().toInt()
    );//分钟
    c.set(Calendar.SECOND, 0);//秒
   }
   //计时发送通知
   val mIntent = Intent(this, MyReceiver::class.java)
   val mPendingIntent =
    PendingIntent.getBroadcast(this, 0, mIntent, PendingIntent.FLAG_UPDATE_CURRENT)
   am = this
    .getSystemService(Context.ALARM_SERVICE) as AlarmManager
   if (setHour.text.toString()==""||setMin.text.toString()==""||
    setHour.text.toString().toInt() > 24 || setMin.text.toString().toInt() > 60) {
    Toast.makeText(this, "请输入正确的时间格式！", Toast.LENGTH_SHORT).show()
   } else {
    Log.d("fuck10", c.timeInMillis.toString())
    am!!.setExactAndAllowWhileIdle(
     AlarmManager.RTC_WAKEUP, c.timeInMillis,
     mPendingIntent
    )
    Toast.makeText(this, "设置成功", Toast.LENGTH_SHORT).show()
   }
  }