我是Android Kotlin的新手。单击应用上的按钮时,我尝试从Cloud Firebase删除数据。我在适配器上做了一些必要的代码,但是如何在Activity上调用数据库集合?ı在下面分享了我的适配器和我的活动代码。
class NoteAdapter(val titleText: ArrayList<String>, val rowImage: ArrayList<String>, val noteText: ArrayList<String>, val listener: onClick) : RecyclerView.Adapter<NoteAdapter.NoteHolder>() {
interface onClick {
fun onItemClickListener(v: View, pos: Int, data: Any)
}
class NoteHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val itemImage : ImageView = itemView.findViewById(R.id.recyclerImage)
val itemDelete: ImageView = itemView.findViewById(R.id.delete)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): NoteHolder {
val v = LayoutInflater.from(parent.context).inflate(R.layout.recycler_row, parent, false)
return NoteHolder(v)
}
override fun onBindViewHolder(holder: NoteHolder, position: Int) {
holder.itemView.recyclerTitleText.text = titleText[position]
Picasso.get().load(rowImage[position]).resize(150,150).into(holder.itemImage)
holder.itemView.setOnClickListener {
val intent = Intent(holder.itemView.context, PastNotesActivity:: class.java)
intent.putExtra("oldTitle", titleText[position])
intent.putExtra("oldNote", noteText[position])
intent.putExtra("oldImage", rowImage[position])
holder.itemView.context.startActivity(intent)
}
holder.itemDelete.setOnClickListener { v: View ->
titleText.removeAt(position)
noteText.removeAt(position)
rowImage.removeAt(position)
notifyItemRemoved(position)
listener.onItemClickListener(v, position, holder.itemView)
}
}
override fun getItemCount(): Int {
return titleText.size
}
override fun getItemId(position: Int):Long {
return position.toLong()
}
override fun getItemViewType(position: Int):Int {
return position
}
}
这是我的活动代码,我在此活动中创建itemDelete乐趣,但是如何在此乐趣中定义适配器代码?并且我尝试在文档中写“ {id.data}”,但没有用,我应该写什么?
class ListViewActivity : AppCompatActivity() {
var selectedPicture: Uri? = null
private lateinit var auth: FirebaseAuth
private lateinit var db : FirebaseFirestore
var titleTextFromFB : ArrayList<String> = ArrayList()
var noteTextFromFB : ArrayList<String> = ArrayList()
var imageFromFB : ArrayList<String> = ArrayList()
var adapter: NoteAdapter? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_list_view)
auth = FirebaseAuth.getInstance()
db = FirebaseFirestore.getInstance()
getDataFromFirestore()
// recyclerview
var layoutManager = LinearLayoutManager(this)
recyclerView.layoutManager = layoutManager
// adapter = NoteAdapter(titleTextFromFB, imageFromFB, noteTextFromFB)
//recyclerView.adapter = adapter
adapter = NoteAdapter(titleTextFromFB, imageFromFB, noteTextFromFB, object: NoteAdapter.onClick{
override fun onItemClickListener(v: View, pos: Int, data: Any) {
when(v.id){
R.id.delete -> itemDelete(data)
}
}
})
recyclerView.adapter = adapter
}
override fun onCreateOptionsMenu(menu: Menu?): Boolean {
val menuInflater = menuInflater
menuInflater.inflate(R.menu.add_note, menu)
return super.onCreateOptionsMenu(menu)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
if (item.itemId == R.id.add_note_click) {
// Take Notes Activity
val intent = Intent(applicationContext, TakeNotesActivity::class.java)
intent.putExtra("info","new")
startActivity(intent)
} else if (item.itemId == R.id.log_out) {
val alert = AlertDialog.Builder(this)
alert.setTitle("Log Out")
alert.setMessage("Are you sure to logout from the app ?")
alert.setPositiveButton("Yes") {dialog, which ->
auth.signOut()
val intent = Intent(applicationContext, MainActivity::class.java)
startActivity(intent)
finish()
}
alert.setNegativeButton("No") {dialog, which ->
}
alert.show()
}
return super.onOptionsItemSelected(item)
}
// get data from firestore
fun getDataFromFirestore() {
db.collection("Notes").orderBy("date", Query.Direction.DESCENDING).addSnapshotListener{ snapshot, exception ->
if (exception != null) {
// If there is a error ,
Toast.makeText(applicationContext, exception.localizedMessage.toString(), Toast.LENGTH_LONG).show()
} else {
if (snapshot != null) {
if (!snapshot.isEmpty) {
titleTextFromFB.clear()
noteTextFromFB.clear()
imageFromFB.clear()
val documents = snapshot.documents
for (document in documents) {
val userEmail = document.get("userEmail") as String
val noteTitle = document.get("noteTitle") as String
val yourNote = document.get("yourNote") as String
val downloadUrl = document.get("downloadUrl") as String
val timestamp = document.get("date") as Timestamp
val date = timestamp.toDate()
titleTextFromFB.add(noteTitle)
imageFromFB.add(downloadUrl)
noteTextFromFB.add(yourNote)
adapter!!.notifyDataSetChanged()
}
}
}
}
}
}
fun itemDelete(data: Any) {
db.collection("Notes").document().delete().addOnSuccessListener {
}
.addOnFailureListener { exception ->
Toast.makeText(applicationContext, exception.localizedMessage.toString(), Toast.LENGTH_LONG).show()
}
}
}
此代码无法正常工作:
db.collection("Notes").document().delete().addOnSuccessListener {
该db.collection("Notes").document()
调用将创建对新文档的引用,然后将其删除。所以什么也没发生。
您需要确定用户单击的文档的ID,并将其传递给document(...)
呼叫。这样可以为您提供DocumentReference
正确的文档,以便delete()
呼叫将随后删除该文档。
确定用户单击的文档ID的关键在以下代码中:
adapter = NoteAdapter(titleTextFromFB, imageFromFB, noteTextFromFB, object: NoteAdapter.onClick{
override fun onItemClickListener(v: View, pos: Int, data: Any) {
when(v.id){
R.id.delete -> itemDelete(data)
}
}
})
您将需要从这些参数之一来确定ID: v
,post
或data
。我通常通过DocumentSnapshot
在适配器或活动中保留文档ID或对象的列表,然后按其位置/索引查找单击的项目来完成此操作。
因此,在getDataFromFirestore
函数中,将快照添加到您在活动类中定义为字段的列表中:
// in your activity, declare a list;
var mDocuments: List<DocumentSnapshot>? = null
// Then in getDataFromFirestore store that list
...
mDocuments = snapshot.documents;
val documents = snapshot.documents
for (document in documents) {
...
}
...
// And use it when calling itemDelete:
adapter = NoteAdapter(titleTextFromFB, imageFromFB, noteTextFromFB, object: NoteAdapter.onClick{
override fun onItemClickListener(v: View, pos: Int, data: Any) {
when(v.id){
R.id.delete -> itemDelete(mDocuments[pos])
}
}
})
// To then finally delete the document by its ID
fun itemDelete(doc: DocumentSnapshot) {
db.collection("Notes").document(doc.Id).delete()
}
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