如何将所有颤动小部件的默认标高设置为零，例如包括 // message get seen function
private fun seenMessage(receiverId: String) {
val databaseReference = FirebaseDatabase.getInstance()
.getReference(CHATS)
databaseReference.addListenerForSingleValueEvent(object : ValueEventListener {
override fun onDataChange(dataSnapshot: DataSnapshot) {
for (snapshot in dataSnapshot.children) {
val message = snapshot.getValue(Message::class.java)!!
if (message.receiver.equals(currentUserId) && message.sender.equals( receiverId )) {
val hashMap = HashMap<String, Any>()
hashMap["isseen"] = true
snapshot.ref.updateChildren(hashMap)
}
}
}
override fun onCancelled(databaseError: DatabaseError) {
}
})
}`
和DropdownButton？
我想创建一个纯色应用程序。