本文实例为大家分享了Android实现记事本功能的具体代码，供大家参考，具体内容如下

首先声明，本人是android的小白，主要是新人项目写了这个程序，思路可能不是很清晰，可优化的地方也有很多，望路过的大佬不吝赐教。
该记事本包含创建新条目，数据库增删改查，条目可编辑，滑动删除与拖拽排序，简单闹钟实现（还有个简陋背景音乐开关就不提了太简单），接下来逐一介绍一下。

build.gradle导入

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"

没什么多说的。

Room数据库

room数据库相比于sqlite来说对新人确实友好很多，在没有SQL基础的前提下，增删改查等实现都很简单，只需创建一个实例，便可在线程中进行。具体代码为

①接口：

@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)

}

②Appdatabase类（获取实例）

@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

}

}

}

}

滑动删除和拖拽排序

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)

}

}

 

NoteAdapter接口实现

拖拽排序和滑动删除后即更新一次，这种方法并不好，毕竟没有用到MVVM中的高级组件，包括观察者，Livedata，ViewModel察觉数据变化并提示更新。建议在这种方法的前提下可以考虑在从Activity离开后，再数据更新。

注：千万不要在**onPause()**中涉及数据更新和保存！！！

//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)

}

简易闹钟实现

broadcast类需要自己实现

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()

}

}

这里只是发个广播通知，并没有提示声音，可以采取发到通知栏的方式，系统会有提示音。涉及到AlarmManager类

NoteActivity中的实现：

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()

}

}

其它方面如点击recyclerView中的Item重新编辑时对原数据的展现，用到了setText()，这里注意不要跟kotlin中setText()和getText()搞混。

大概所有功能差不多就这些了，毕竟只是个记事本应用。

所有代码放在github上面了，如有需要，请自取

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持A5源码。