Android实现记事本小功能

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。