DataSnapshot不存在

Question

如果存在dataSnapshot，流程将继续执行if语句 但是我尝试了很多数据保存在firbase上 使用此代码dataSnapshot不存在

DataBase Structure >

 private  void getAssignedCustomer(){
    String driverId = FirebaseAuth.getInstance().getCurrentUser().getUid();

    DatabaseReference assignedCustomerRef = FirebaseDatabase.getInstance().getReference().child("Users").child("Drivers").child(driverId).child("customerRideId");
    assignedCustomerRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

            if(dataSnapshot.getValue() !=null){


                    cutomerId =dataSnapshot.getValue().toString();
                    getAssignedCustomerPickupLocation();

            }else{

                Toast.makeText(DriverMapActivity.this , "data snap not exist", Toast.LENGTH_SHORT).show();
            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });
}

Answer 1

由于这些原因，不存在常见原因datasnapshort。

1.child路径名与firebase json树路径名不匹配。

2。您的路径中不存在数据。

请更改此

 if(dataSnapshot.getValue()!=null){
          cutomerId =dataSnapshot.getValue().toString();
                        getAssignedCustomerPickupLocation();

                }else{

                    Toast.makeText(DriverMapActivity.this , "data snap not exist", Toast.LENGTH_SHORT).show();
                };

对此

 if(dataSnapshot.exists()){
     cutomerId =dataSnapshot.getValue(String.class);
                        getAssignedCustomerPickupLocation();

                }else{

                    Toast.makeText(DriverMapActivity.this , "data snap not exist", Toast.LENGTH_SHORT).show();
                };