Android 如何从firebase检索数据列表并将其存储到ArrayList
我有一个Firebase数据库，我想从那里检索数据列表并存储到ArrayList中 产品型号很好，工作正常Android 如何从firebase检索数据列表并将其存储到ArrayList,android,firebase,kotlin,arraylist,firebase-realtime-database,Android,Firebase,Kotlin,Arraylist,Firebase Realtime Database,我有一个Firebase数据库，我想从那里检索数据列表并存储到ArrayList中 产品型号很好，工作正常 class Product(var pName: String?, var pUnit: Int, var pPrice: Double, var pAmount: Double) 但不知何故，我无法从数据库中获取项目列表。 我想要的是获取pname、punit、pprice和pamount并将其存储在ArrayList中 我对数据库的引用是这样的 ref = FirebaseData
class Product(var pName: String?, var pUnit: Int, var pPrice: Double, var pAmount: Double)
ref = FirebaseDatabase.getInstance().getReference().child("Sales")
ref.addValueEventListener(object : ValueEventListener{
override fun onCancelled(p0: DatabaseError) {
}
override fun onDataChange(p0: DataSnapshot) {
var sira: Int = 0
ref.addListenerForSingleValueEvent(object : ValueEventListener {
override fun onCancelled(p0: DatabaseError) {
}
override fun onDataChange(p1: DataSnapshot) {
println("onDataChange")
if (p0.exists()) {
list.clear()
for (h in p0.children) {
val dateR = h.child("date").value.toString()
val discountR = h.child("discount").value.toString()
val dueR = h.child("due").value.toString()
val nameR = h.child("name").value.toString()
val totalR = h.child("total").value.toString()
val subtotalR = h.child("subTotal").value.toString()
val timeR = h.child("time").value.toString()
val name = h.child("pname").value.toString()
val unit = h.child("punit").value.toString()
val price = h.child("pprice").value.toString()
val amount = h.child("pamount").value.toString()
productList.add(Product(name, unit.toInt(), price.toDouble(), amount.toDouble()))
谢谢。您能否尝试：使用GenericTypeIndicator获取列表数据 您可以参考我的github：
你能导出文件数据firebase吗？我想导入firebase并测试你的问题中包含了JSON树的图片。请将其替换为实际的JSON文本，您可以通过单击溢出菜单中的导出JSON链接轻松获得该文本⠇ 属于将JSON作为文本使其具有可搜索性，使我们能够轻松地使用它来测试您的实际数据，并在我们的答案中使用它，这通常是一件好事。您好，感谢您的关注。我在问题中添加了json文件。我回答了您可以检查的问题。我注意到这种方式只能从firebase获取所有产品条目。是否可以使其仅基于特定的键值显示。例如，我希望它只显示`-Lw5Qx8sVdw3ZCMiXAL-`key？Hi'下的产品列表，感谢您的回答，但它给出了一个错误com.google.firebase.database.DatabaseException:不支持通用通配符类型您可以将列表修复为ArrayList:val-Generic:GenericTypeIndicator=object:GenericTypeIndicator{}谢谢，@Cườ吴恩圭ễ与ArrayList合作的n。很好的解决方案。
{
"-Lw37--uyfuBA0AfTalp" : {
"date" : "14/12/2019",
"discount" : 0.24,
"due" : 0,
"items" : [ {
"pamount" : 2.4,
"pname" : "Granola",
"pprice" : 2.4,
"punit" : 1
} ],
"paym" : [ {
"paymentAmnt" : 0.02,
"paymentDesc" : "Cash Payment :"
}, {
"paymentAmnt" : 2.14,
"paymentDesc" : "Card Payment :"
} ],
"subTotal" : 2.4,
"time" : "11:16:42",
"total" : 2.16
},
"-Lw5Qx8sVdw3ZCMiXAL-" : {
"date" : "14/12/2019",
"discount" : 1,
"due" : 0,
"items" : [ {
"pamount" : 4.8,
"pname" : "Granola",
"pprice" : 2.4,
"punit" : 2
}, {
"pamount" : 2.6,
"pname" : "Brownie",
"pprice" : 2.6,
"punit" : 1
}, {
"pamount" : 2.6,
"pname" : "Brownie",
"pprice" : 2.6,
"punit" : 1
} ],
"name" : "James Brown",
"paym" : [ {
"paymentAmnt" : 3,
"paymentDesc" : "Cash Payment :"
}, {
"paymentAmnt" : 5,
"paymentDesc" : "Staff Markout :"
}, {
"paymentAmnt" : 1,
"paymentDesc" : "Card Payment :"
} ],
"subTotal" : 10,
"time" : "22:03:07",
"total" : 9
},
"-Lw5T4TfYUTXsWKAndBx" : {
"date" : "14/12/2019",
"discount" : 0.24,
"due" : -0.84,
"items" : [ {
"pamount" : 2.4,
"pname" : "Granola",
"pprice" : 2.4,
"punit" : 1
} ],
"name" : "James Brown",
"paym" : [ {
"paymentAmnt" : 3,
"paymentDesc" : "Cash Payment :"
} ],
"subTotal" : 2.4,
"time" : "22:12:26",
"total" : 2.16
},
"-Lw5UWguHS18IwWE6elT" : {
"date" : "14/12/2019",
"discount" : 0.26,
"due" : -1.66,
"items" : [ {
"pamount" : 2.6,
"pname" : "Brownie",
"pprice" : 2.6,
"punit" : 1
} ],
"name" : "James Brown",
"paym" : [ {
"paymentAmnt" : 4,
"paymentDesc" : "Cash Payment :"
} ],
"subTotal" : 2.6,
"time" : "22:18:43",
"total" : 2.34
},
"-Lw5ypp5xJLJO53bjejk" : {
"date" : "15/12/2019",
"discount" : 0,
"due" : -1.6,
"items" : [ {
"pamount" : 2.4,
"pname" : "Granola",
"pprice" : 2.4,
"punit" : 1
} ],
"name" : "James Brown",
"paym" : [ {
"paymentAmnt" : 4,
"paymentDesc" : "Cash Payment :"
} ],
"subTotal" : 2.4,
"time" : "00:35:32",
"total" : 2.4
},
"-LwANPC0UYCmTnqm7DRV" : {
"date" : "15/12/2019",
"discount" : 1,
"due" : 0,
"items" : [ {
"pamount" : 2.4,
"pname" : "Granola",
"pprice" : 2.4,
"punit" : 1
}, {
"pamount" : 2.6,
"pname" : "Brownie",
"pprice" : 2.6,
"punit" : 1
}, {
"pamount" : 2.4,
"pname" : "Granola",
"pprice" : 2.4,
"punit" : 1
}, {
"pamount" : 2.6,
"pname" : "Brownie",
"pprice" : 2.6,
"punit" : 1
} ],
"name" : "James Brown",
"paym" : [ {
"paymentAmnt" : 5,
"paymentDesc" : "Cash Payment :"
}, {
"paymentAmnt" : 4,
"paymentDesc" : "Card Payment :"
} ],
"subTotal" : 10,
"time" : "21:05:43",
"total" : 9
}
}
private lateinit var database: DatabaseReference
private var productList: ArrayList<Product> = arrayListOf()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
database = FirebaseDatabase.getInstance().getReference("Sales")
database.addValueEventListener(object: ValueEventListener {
override fun onCancelled(p0: DatabaseError) {
}
override fun onDataChange(p0: DataSnapshot) {
productList.clear()
for (snapshot in p0.children) {
if (snapshot.hasChild("items")) {
val generic: GenericTypeIndicator<List<Product>> =
object : GenericTypeIndicator<List<Product>>() {}
val items = snapshot.child("items").getValue(generic)
items?.let { productList.addAll(it) }
}
}
}
})
}
class Product {
var pName: String? = null
var pUnit: Int? = null
var pPrice: Double? = null
var pAmount: Double? = null
}